4 TGSI, Tungsten Graphics Shader Infrastructure, is an intermediate language
5 for describing shaders. Since Gallium is inherently shaderful, shaders are
6 an important part of the API. TGSI is the only intermediate representation
12 All TGSI instructions, known as *opcodes*, operate on arbitrary-precision
13 floating-point four-component vectors. An opcode may have up to one
14 destination register, known as *dst*, and between zero and three source
15 registers, called *src0* through *src2*, or simply *src* if there is only
18 Some instructions, like :opcode:`I2F`, permit re-interpretation of vector
19 components as integers. Other instructions permit using registers as
20 two-component vectors with double precision; see :ref:`doubleopcodes`.
22 When an instruction has a scalar result, the result is usually copied into
23 each of the components of *dst*. When this happens, the result is said to be
24 *replicated* to *dst*. :opcode:`RCP` is one such instruction.
29 TGSI supports modifiers on inputs (as well as saturate modifier on instructions).
31 For inputs which have a floating point type, both absolute value and negation
32 modifiers are supported (with absolute value being applied first).
33 TGSI_OPCODE_MOV is considered to have float input type for applying modifiers.
35 For inputs which have signed or unsigned type only the negate modifier is
42 ^^^^^^^^^^^^^^^^^^^^^^^^^
44 These opcodes are guaranteed to be available regardless of the driver being
47 .. opcode:: ARL - Address Register Load
51 dst.x = (int) \lfloor src.x\rfloor
53 dst.y = (int) \lfloor src.y\rfloor
55 dst.z = (int) \lfloor src.z\rfloor
57 dst.w = (int) \lfloor src.w\rfloor
60 .. opcode:: MOV - Move
73 .. opcode:: LIT - Light Coefficients
78 dst.y &= max(src.x, 0) \\
79 dst.z &= (src.x > 0) ? max(src.y, 0)^{clamp(src.w, -128, 128))} : 0 \\
83 .. opcode:: RCP - Reciprocal
85 This instruction replicates its result.
92 .. opcode:: RSQ - Reciprocal Square Root
94 This instruction replicates its result. The results are undefined for src <= 0.
98 dst = \frac{1}{\sqrt{src.x}}
101 .. opcode:: SQRT - Square Root
103 This instruction replicates its result. The results are undefined for src < 0.
110 .. opcode:: EXP - Approximate Exponential Base 2
114 dst.x &= 2^{\lfloor src.x\rfloor} \\
115 dst.y &= src.x - \lfloor src.x\rfloor \\
116 dst.z &= 2^{src.x} \\
120 .. opcode:: LOG - Approximate Logarithm Base 2
124 dst.x &= \lfloor\log_2{|src.x|}\rfloor \\
125 dst.y &= \frac{|src.x|}{2^{\lfloor\log_2{|src.x|}\rfloor}} \\
126 dst.z &= \log_2{|src.x|} \\
130 .. opcode:: MUL - Multiply
134 dst.x = src0.x \times src1.x
136 dst.y = src0.y \times src1.y
138 dst.z = src0.z \times src1.z
140 dst.w = src0.w \times src1.w
143 .. opcode:: ADD - Add
147 dst.x = src0.x + src1.x
149 dst.y = src0.y + src1.y
151 dst.z = src0.z + src1.z
153 dst.w = src0.w + src1.w
156 .. opcode:: DP3 - 3-component Dot Product
158 This instruction replicates its result.
162 dst = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z
165 .. opcode:: DP4 - 4-component Dot Product
167 This instruction replicates its result.
171 dst = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src0.w \times src1.w
174 .. opcode:: DST - Distance Vector
179 dst.y &= src0.y \times src1.y\\
184 .. opcode:: MIN - Minimum
188 dst.x = min(src0.x, src1.x)
190 dst.y = min(src0.y, src1.y)
192 dst.z = min(src0.z, src1.z)
194 dst.w = min(src0.w, src1.w)
197 .. opcode:: MAX - Maximum
201 dst.x = max(src0.x, src1.x)
203 dst.y = max(src0.y, src1.y)
205 dst.z = max(src0.z, src1.z)
207 dst.w = max(src0.w, src1.w)
210 .. opcode:: SLT - Set On Less Than
214 dst.x = (src0.x < src1.x) ? 1.0F : 0.0F
216 dst.y = (src0.y < src1.y) ? 1.0F : 0.0F
218 dst.z = (src0.z < src1.z) ? 1.0F : 0.0F
220 dst.w = (src0.w < src1.w) ? 1.0F : 0.0F
223 .. opcode:: SGE - Set On Greater Equal Than
227 dst.x = (src0.x >= src1.x) ? 1.0F : 0.0F
229 dst.y = (src0.y >= src1.y) ? 1.0F : 0.0F
231 dst.z = (src0.z >= src1.z) ? 1.0F : 0.0F
233 dst.w = (src0.w >= src1.w) ? 1.0F : 0.0F
236 .. opcode:: MAD - Multiply And Add
240 dst.x = src0.x \times src1.x + src2.x
242 dst.y = src0.y \times src1.y + src2.y
244 dst.z = src0.z \times src1.z + src2.z
246 dst.w = src0.w \times src1.w + src2.w
249 .. opcode:: SUB - Subtract
253 dst.x = src0.x - src1.x
255 dst.y = src0.y - src1.y
257 dst.z = src0.z - src1.z
259 dst.w = src0.w - src1.w
262 .. opcode:: LRP - Linear Interpolate
266 dst.x = src0.x \times src1.x + (1 - src0.x) \times src2.x
268 dst.y = src0.y \times src1.y + (1 - src0.y) \times src2.y
270 dst.z = src0.z \times src1.z + (1 - src0.z) \times src2.z
272 dst.w = src0.w \times src1.w + (1 - src0.w) \times src2.w
275 .. opcode:: DP2A - 2-component Dot Product And Add
279 dst.x = src0.x \times src1.x + src0.y \times src1.y + src2.x
281 dst.y = src0.x \times src1.x + src0.y \times src1.y + src2.x
283 dst.z = src0.x \times src1.x + src0.y \times src1.y + src2.x
285 dst.w = src0.x \times src1.x + src0.y \times src1.y + src2.x
288 .. opcode:: FRC - Fraction
292 dst.x = src.x - \lfloor src.x\rfloor
294 dst.y = src.y - \lfloor src.y\rfloor
296 dst.z = src.z - \lfloor src.z\rfloor
298 dst.w = src.w - \lfloor src.w\rfloor
301 .. opcode:: CLAMP - Clamp
305 dst.x = clamp(src0.x, src1.x, src2.x)
307 dst.y = clamp(src0.y, src1.y, src2.y)
309 dst.z = clamp(src0.z, src1.z, src2.z)
311 dst.w = clamp(src0.w, src1.w, src2.w)
314 .. opcode:: FLR - Floor
318 dst.x = \lfloor src.x\rfloor
320 dst.y = \lfloor src.y\rfloor
322 dst.z = \lfloor src.z\rfloor
324 dst.w = \lfloor src.w\rfloor
327 .. opcode:: ROUND - Round
340 .. opcode:: EX2 - Exponential Base 2
342 This instruction replicates its result.
349 .. opcode:: LG2 - Logarithm Base 2
351 This instruction replicates its result.
358 .. opcode:: POW - Power
360 This instruction replicates its result.
364 dst = src0.x^{src1.x}
366 .. opcode:: XPD - Cross Product
370 dst.x = src0.y \times src1.z - src1.y \times src0.z
372 dst.y = src0.z \times src1.x - src1.z \times src0.x
374 dst.z = src0.x \times src1.y - src1.x \times src0.y
379 .. opcode:: ABS - Absolute
392 .. opcode:: DPH - Homogeneous Dot Product
394 This instruction replicates its result.
398 dst = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src1.w
401 .. opcode:: COS - Cosine
403 This instruction replicates its result.
410 .. opcode:: DDX, DDX_FINE - Derivative Relative To X
412 The fine variant is only used when ``PIPE_CAP_TGSI_FS_FINE_DERIVATIVE`` is
413 advertised. When it is, the fine version guarantees one derivative per row
414 while DDX is allowed to be the same for the entire 2x2 quad.
418 dst.x = partialx(src.x)
420 dst.y = partialx(src.y)
422 dst.z = partialx(src.z)
424 dst.w = partialx(src.w)
427 .. opcode:: DDY, DDY_FINE - Derivative Relative To Y
429 The fine variant is only used when ``PIPE_CAP_TGSI_FS_FINE_DERIVATIVE`` is
430 advertised. When it is, the fine version guarantees one derivative per column
431 while DDY is allowed to be the same for the entire 2x2 quad.
435 dst.x = partialy(src.x)
437 dst.y = partialy(src.y)
439 dst.z = partialy(src.z)
441 dst.w = partialy(src.w)
444 .. opcode:: PK2H - Pack Two 16-bit Floats
449 .. opcode:: PK2US - Pack Two Unsigned 16-bit Scalars
454 .. opcode:: PK4B - Pack Four Signed 8-bit Scalars
459 .. opcode:: PK4UB - Pack Four Unsigned 8-bit Scalars
464 .. opcode:: SEQ - Set On Equal
468 dst.x = (src0.x == src1.x) ? 1.0F : 0.0F
470 dst.y = (src0.y == src1.y) ? 1.0F : 0.0F
472 dst.z = (src0.z == src1.z) ? 1.0F : 0.0F
474 dst.w = (src0.w == src1.w) ? 1.0F : 0.0F
477 .. opcode:: SGT - Set On Greater Than
481 dst.x = (src0.x > src1.x) ? 1.0F : 0.0F
483 dst.y = (src0.y > src1.y) ? 1.0F : 0.0F
485 dst.z = (src0.z > src1.z) ? 1.0F : 0.0F
487 dst.w = (src0.w > src1.w) ? 1.0F : 0.0F
490 .. opcode:: SIN - Sine
492 This instruction replicates its result.
499 .. opcode:: SLE - Set On Less Equal Than
503 dst.x = (src0.x <= src1.x) ? 1.0F : 0.0F
505 dst.y = (src0.y <= src1.y) ? 1.0F : 0.0F
507 dst.z = (src0.z <= src1.z) ? 1.0F : 0.0F
509 dst.w = (src0.w <= src1.w) ? 1.0F : 0.0F
512 .. opcode:: SNE - Set On Not Equal
516 dst.x = (src0.x != src1.x) ? 1.0F : 0.0F
518 dst.y = (src0.y != src1.y) ? 1.0F : 0.0F
520 dst.z = (src0.z != src1.z) ? 1.0F : 0.0F
522 dst.w = (src0.w != src1.w) ? 1.0F : 0.0F
525 .. opcode:: TEX - Texture Lookup
527 for array textures src0.y contains the slice for 1D,
528 and src0.z contain the slice for 2D.
530 for shadow textures with no arrays (and not cube map),
531 src0.z contains the reference value.
533 for shadow textures with arrays, src0.z contains
534 the reference value for 1D arrays, and src0.w contains
535 the reference value for 2D arrays and cube maps.
537 for cube map array shadow textures, the reference value
538 cannot be passed in src0.w, and TEX2 must be used instead.
544 shadow_ref = src0.z or src0.w (optional)
548 dst = texture\_sample(unit, coord, shadow_ref)
551 .. opcode:: TEX2 - Texture Lookup (for shadow cube map arrays only)
553 this is the same as TEX, but uses another reg to encode the
564 dst = texture\_sample(unit, coord, shadow_ref)
569 .. opcode:: TXD - Texture Lookup with Derivatives
581 dst = texture\_sample\_deriv(unit, coord, ddx, ddy)
584 .. opcode:: TXP - Projective Texture Lookup
588 coord.x = src0.x / src0.w
590 coord.y = src0.y / src0.w
592 coord.z = src0.z / src0.w
598 dst = texture\_sample(unit, coord)
601 .. opcode:: UP2H - Unpack Two 16-Bit Floats
607 Considered for removal.
609 .. opcode:: UP2US - Unpack Two Unsigned 16-Bit Scalars
615 Considered for removal.
617 .. opcode:: UP4B - Unpack Four Signed 8-Bit Values
623 Considered for removal.
625 .. opcode:: UP4UB - Unpack Four Unsigned 8-Bit Scalars
631 Considered for removal.
634 .. opcode:: ARR - Address Register Load With Round
638 dst.x = (int) round(src.x)
640 dst.y = (int) round(src.y)
642 dst.z = (int) round(src.z)
644 dst.w = (int) round(src.w)
647 .. opcode:: SSG - Set Sign
651 dst.x = (src.x > 0) ? 1 : (src.x < 0) ? -1 : 0
653 dst.y = (src.y > 0) ? 1 : (src.y < 0) ? -1 : 0
655 dst.z = (src.z > 0) ? 1 : (src.z < 0) ? -1 : 0
657 dst.w = (src.w > 0) ? 1 : (src.w < 0) ? -1 : 0
660 .. opcode:: CMP - Compare
664 dst.x = (src0.x < 0) ? src1.x : src2.x
666 dst.y = (src0.y < 0) ? src1.y : src2.y
668 dst.z = (src0.z < 0) ? src1.z : src2.z
670 dst.w = (src0.w < 0) ? src1.w : src2.w
673 .. opcode:: KILL_IF - Conditional Discard
675 Conditional discard. Allowed in fragment shaders only.
679 if (src.x < 0 || src.y < 0 || src.z < 0 || src.w < 0)
684 .. opcode:: KILL - Discard
686 Unconditional discard. Allowed in fragment shaders only.
689 .. opcode:: SCS - Sine Cosine
702 .. opcode:: TXB - Texture Lookup With Bias
704 for cube map array textures and shadow cube maps, the bias value
705 cannot be passed in src0.w, and TXB2 must be used instead.
707 if the target is a shadow texture, the reference value is always
708 in src.z (this prevents shadow 3d and shadow 2d arrays from
709 using this instruction, but this is not needed).
725 dst = texture\_sample(unit, coord, bias)
728 .. opcode:: TXB2 - Texture Lookup With Bias (some cube maps only)
730 this is the same as TXB, but uses another reg to encode the
731 lod bias value for cube map arrays and shadow cube maps.
732 Presumably shadow 2d arrays and shadow 3d targets could use
733 this encoding too, but this is not legal.
735 shadow cube map arrays are neither possible nor required.
745 dst = texture\_sample(unit, coord, bias)
748 .. opcode:: DIV - Divide
752 dst.x = \frac{src0.x}{src1.x}
754 dst.y = \frac{src0.y}{src1.y}
756 dst.z = \frac{src0.z}{src1.z}
758 dst.w = \frac{src0.w}{src1.w}
761 .. opcode:: DP2 - 2-component Dot Product
763 This instruction replicates its result.
767 dst = src0.x \times src1.x + src0.y \times src1.y
770 .. opcode:: TXL - Texture Lookup With explicit LOD
772 for cube map array textures, the explicit lod value
773 cannot be passed in src0.w, and TXL2 must be used instead.
775 if the target is a shadow texture, the reference value is always
776 in src.z (this prevents shadow 3d / 2d array / cube targets from
777 using this instruction, but this is not needed).
793 dst = texture\_sample(unit, coord, lod)
796 .. opcode:: TXL2 - Texture Lookup With explicit LOD (for cube map arrays only)
798 this is the same as TXL, but uses another reg to encode the
800 Presumably shadow 3d / 2d array / cube targets could use
801 this encoding too, but this is not legal.
803 shadow cube map arrays are neither possible nor required.
813 dst = texture\_sample(unit, coord, lod)
816 .. opcode:: PUSHA - Push Address Register On Stack
825 Considered for cleanup.
829 Considered for removal.
831 .. opcode:: POPA - Pop Address Register From Stack
840 Considered for cleanup.
844 Considered for removal.
847 .. opcode:: CALLNZ - Subroutine Call If Not Zero
853 Considered for cleanup.
857 Considered for removal.
861 ^^^^^^^^^^^^^^^^^^^^^^^^
863 These opcodes are primarily provided for special-use computational shaders.
864 Support for these opcodes indicated by a special pipe capability bit (TBD).
866 XXX doesn't look like most of the opcodes really belong here.
868 .. opcode:: CEIL - Ceiling
872 dst.x = \lceil src.x\rceil
874 dst.y = \lceil src.y\rceil
876 dst.z = \lceil src.z\rceil
878 dst.w = \lceil src.w\rceil
881 .. opcode:: TRUNC - Truncate
894 .. opcode:: MOD - Modulus
898 dst.x = src0.x \bmod src1.x
900 dst.y = src0.y \bmod src1.y
902 dst.z = src0.z \bmod src1.z
904 dst.w = src0.w \bmod src1.w
907 .. opcode:: UARL - Integer Address Register Load
909 Moves the contents of the source register, assumed to be an integer, into the
910 destination register, which is assumed to be an address (ADDR) register.
913 .. opcode:: SAD - Sum Of Absolute Differences
917 dst.x = |src0.x - src1.x| + src2.x
919 dst.y = |src0.y - src1.y| + src2.y
921 dst.z = |src0.z - src1.z| + src2.z
923 dst.w = |src0.w - src1.w| + src2.w
926 .. opcode:: TXF - Texel Fetch
928 As per NV_gpu_shader4, extract a single texel from a specified texture
929 image. The source sampler may not be a CUBE or SHADOW. src 0 is a
930 four-component signed integer vector used to identify the single texel
931 accessed. 3 components + level. Just like texture instructions, an optional
932 offset vector is provided, which is subject to various driver restrictions
933 (regarding range, source of offsets).
934 TXF(uint_vec coord, int_vec offset).
937 .. opcode:: TXQ - Texture Size Query
939 As per NV_gpu_program4, retrieve the dimensions of the texture depending on
940 the target. For 1D (width), 2D/RECT/CUBE (width, height), 3D (width, height,
941 depth), 1D array (width, layers), 2D array (width, height, layers).
942 Also return the number of accessible levels (last_level - first_level + 1)
945 For components which don't return a resource dimension, their value
953 dst.x = texture\_width(unit, lod)
955 dst.y = texture\_height(unit, lod)
957 dst.z = texture\_depth(unit, lod)
959 dst.w = texture\_levels(unit)
961 .. opcode:: TG4 - Texture Gather
963 As per ARB_texture_gather, gathers the four texels to be used in a bi-linear
964 filtering operation and packs them into a single register. Only works with
965 2D, 2D array, cubemaps, and cubemaps arrays. For 2D textures, only the
966 addressing modes of the sampler and the top level of any mip pyramid are
967 used. Set W to zero. It behaves like the TEX instruction, but a filtered
968 sample is not generated. The four samples that contribute to filtering are
969 placed into xyzw in clockwise order, starting with the (u,v) texture
970 coordinate delta at the following locations (-, +), (+, +), (+, -), (-, -),
971 where the magnitude of the deltas are half a texel.
973 PIPE_CAP_TEXTURE_SM5 enhances this instruction to support shadow per-sample
974 depth compares, single component selection, and a non-constant offset. It
975 doesn't allow support for the GL independent offset to get i0,j0. This would
976 require another CAP is hw can do it natively. For now we lower that before
985 dst = texture\_gather4 (unit, coord, component)
987 (with SM5 - cube array shadow)
995 dst = texture\_gather (uint, coord, compare)
997 .. opcode:: LODQ - level of detail query
999 Compute the LOD information that the texture pipe would use to access the
1000 texture. The Y component contains the computed LOD lambda_prime. The X
1001 component contains the LOD that will be accessed, based on min/max lod's
1008 dst.xy = lodq(uint, coord);
1011 ^^^^^^^^^^^^^^^^^^^^^^^^
1012 These opcodes are used for integer operations.
1013 Support for these opcodes indicated by PIPE_SHADER_CAP_INTEGERS (all of them?)
1016 .. opcode:: I2F - Signed Integer To Float
1018 Rounding is unspecified (round to nearest even suggested).
1022 dst.x = (float) src.x
1024 dst.y = (float) src.y
1026 dst.z = (float) src.z
1028 dst.w = (float) src.w
1031 .. opcode:: U2F - Unsigned Integer To Float
1033 Rounding is unspecified (round to nearest even suggested).
1037 dst.x = (float) src.x
1039 dst.y = (float) src.y
1041 dst.z = (float) src.z
1043 dst.w = (float) src.w
1046 .. opcode:: F2I - Float to Signed Integer
1048 Rounding is towards zero (truncate).
1049 Values outside signed range (including NaNs) produce undefined results.
1062 .. opcode:: F2U - Float to Unsigned Integer
1064 Rounding is towards zero (truncate).
1065 Values outside unsigned range (including NaNs) produce undefined results.
1069 dst.x = (unsigned) src.x
1071 dst.y = (unsigned) src.y
1073 dst.z = (unsigned) src.z
1075 dst.w = (unsigned) src.w
1078 .. opcode:: UADD - Integer Add
1080 This instruction works the same for signed and unsigned integers.
1081 The low 32bit of the result is returned.
1085 dst.x = src0.x + src1.x
1087 dst.y = src0.y + src1.y
1089 dst.z = src0.z + src1.z
1091 dst.w = src0.w + src1.w
1094 .. opcode:: UMAD - Integer Multiply And Add
1096 This instruction works the same for signed and unsigned integers.
1097 The multiplication returns the low 32bit (as does the result itself).
1101 dst.x = src0.x \times src1.x + src2.x
1103 dst.y = src0.y \times src1.y + src2.y
1105 dst.z = src0.z \times src1.z + src2.z
1107 dst.w = src0.w \times src1.w + src2.w
1110 .. opcode:: UMUL - Integer Multiply
1112 This instruction works the same for signed and unsigned integers.
1113 The low 32bit of the result is returned.
1117 dst.x = src0.x \times src1.x
1119 dst.y = src0.y \times src1.y
1121 dst.z = src0.z \times src1.z
1123 dst.w = src0.w \times src1.w
1126 .. opcode:: IMUL_HI - Signed Integer Multiply High Bits
1128 The high 32bits of the multiplication of 2 signed integers are returned.
1132 dst.x = (src0.x \times src1.x) >> 32
1134 dst.y = (src0.y \times src1.y) >> 32
1136 dst.z = (src0.z \times src1.z) >> 32
1138 dst.w = (src0.w \times src1.w) >> 32
1141 .. opcode:: UMUL_HI - Unsigned Integer Multiply High Bits
1143 The high 32bits of the multiplication of 2 unsigned integers are returned.
1147 dst.x = (src0.x \times src1.x) >> 32
1149 dst.y = (src0.y \times src1.y) >> 32
1151 dst.z = (src0.z \times src1.z) >> 32
1153 dst.w = (src0.w \times src1.w) >> 32
1156 .. opcode:: IDIV - Signed Integer Division
1158 TBD: behavior for division by zero.
1162 dst.x = src0.x \ src1.x
1164 dst.y = src0.y \ src1.y
1166 dst.z = src0.z \ src1.z
1168 dst.w = src0.w \ src1.w
1171 .. opcode:: UDIV - Unsigned Integer Division
1173 For division by zero, 0xffffffff is returned.
1177 dst.x = src0.x \ src1.x
1179 dst.y = src0.y \ src1.y
1181 dst.z = src0.z \ src1.z
1183 dst.w = src0.w \ src1.w
1186 .. opcode:: UMOD - Unsigned Integer Remainder
1188 If second arg is zero, 0xffffffff is returned.
1192 dst.x = src0.x \ src1.x
1194 dst.y = src0.y \ src1.y
1196 dst.z = src0.z \ src1.z
1198 dst.w = src0.w \ src1.w
1201 .. opcode:: NOT - Bitwise Not
1214 .. opcode:: AND - Bitwise And
1218 dst.x = src0.x \& src1.x
1220 dst.y = src0.y \& src1.y
1222 dst.z = src0.z \& src1.z
1224 dst.w = src0.w \& src1.w
1227 .. opcode:: OR - Bitwise Or
1231 dst.x = src0.x | src1.x
1233 dst.y = src0.y | src1.y
1235 dst.z = src0.z | src1.z
1237 dst.w = src0.w | src1.w
1240 .. opcode:: XOR - Bitwise Xor
1244 dst.x = src0.x \oplus src1.x
1246 dst.y = src0.y \oplus src1.y
1248 dst.z = src0.z \oplus src1.z
1250 dst.w = src0.w \oplus src1.w
1253 .. opcode:: IMAX - Maximum of Signed Integers
1257 dst.x = max(src0.x, src1.x)
1259 dst.y = max(src0.y, src1.y)
1261 dst.z = max(src0.z, src1.z)
1263 dst.w = max(src0.w, src1.w)
1266 .. opcode:: UMAX - Maximum of Unsigned Integers
1270 dst.x = max(src0.x, src1.x)
1272 dst.y = max(src0.y, src1.y)
1274 dst.z = max(src0.z, src1.z)
1276 dst.w = max(src0.w, src1.w)
1279 .. opcode:: IMIN - Minimum of Signed Integers
1283 dst.x = min(src0.x, src1.x)
1285 dst.y = min(src0.y, src1.y)
1287 dst.z = min(src0.z, src1.z)
1289 dst.w = min(src0.w, src1.w)
1292 .. opcode:: UMIN - Minimum of Unsigned Integers
1296 dst.x = min(src0.x, src1.x)
1298 dst.y = min(src0.y, src1.y)
1300 dst.z = min(src0.z, src1.z)
1302 dst.w = min(src0.w, src1.w)
1305 .. opcode:: SHL - Shift Left
1307 The shift count is masked with 0x1f before the shift is applied.
1311 dst.x = src0.x << (0x1f \& src1.x)
1313 dst.y = src0.y << (0x1f \& src1.y)
1315 dst.z = src0.z << (0x1f \& src1.z)
1317 dst.w = src0.w << (0x1f \& src1.w)
1320 .. opcode:: ISHR - Arithmetic Shift Right (of Signed Integer)
1322 The shift count is masked with 0x1f before the shift is applied.
1326 dst.x = src0.x >> (0x1f \& src1.x)
1328 dst.y = src0.y >> (0x1f \& src1.y)
1330 dst.z = src0.z >> (0x1f \& src1.z)
1332 dst.w = src0.w >> (0x1f \& src1.w)
1335 .. opcode:: USHR - Logical Shift Right
1337 The shift count is masked with 0x1f before the shift is applied.
1341 dst.x = src0.x >> (unsigned) (0x1f \& src1.x)
1343 dst.y = src0.y >> (unsigned) (0x1f \& src1.y)
1345 dst.z = src0.z >> (unsigned) (0x1f \& src1.z)
1347 dst.w = src0.w >> (unsigned) (0x1f \& src1.w)
1350 .. opcode:: UCMP - Integer Conditional Move
1354 dst.x = src0.x ? src1.x : src2.x
1356 dst.y = src0.y ? src1.y : src2.y
1358 dst.z = src0.z ? src1.z : src2.z
1360 dst.w = src0.w ? src1.w : src2.w
1364 .. opcode:: ISSG - Integer Set Sign
1368 dst.x = (src0.x < 0) ? -1 : (src0.x > 0) ? 1 : 0
1370 dst.y = (src0.y < 0) ? -1 : (src0.y > 0) ? 1 : 0
1372 dst.z = (src0.z < 0) ? -1 : (src0.z > 0) ? 1 : 0
1374 dst.w = (src0.w < 0) ? -1 : (src0.w > 0) ? 1 : 0
1378 .. opcode:: FSLT - Float Set On Less Than (ordered)
1380 Same comparison as SLT but returns integer instead of 1.0/0.0 float
1384 dst.x = (src0.x < src1.x) ? \sim 0 : 0
1386 dst.y = (src0.y < src1.y) ? \sim 0 : 0
1388 dst.z = (src0.z < src1.z) ? \sim 0 : 0
1390 dst.w = (src0.w < src1.w) ? \sim 0 : 0
1393 .. opcode:: ISLT - Signed Integer Set On Less Than
1397 dst.x = (src0.x < src1.x) ? \sim 0 : 0
1399 dst.y = (src0.y < src1.y) ? \sim 0 : 0
1401 dst.z = (src0.z < src1.z) ? \sim 0 : 0
1403 dst.w = (src0.w < src1.w) ? \sim 0 : 0
1406 .. opcode:: USLT - Unsigned Integer Set On Less Than
1410 dst.x = (src0.x < src1.x) ? \sim 0 : 0
1412 dst.y = (src0.y < src1.y) ? \sim 0 : 0
1414 dst.z = (src0.z < src1.z) ? \sim 0 : 0
1416 dst.w = (src0.w < src1.w) ? \sim 0 : 0
1419 .. opcode:: FSGE - Float Set On Greater Equal Than (ordered)
1421 Same comparison as SGE but returns integer instead of 1.0/0.0 float
1425 dst.x = (src0.x >= src1.x) ? \sim 0 : 0
1427 dst.y = (src0.y >= src1.y) ? \sim 0 : 0
1429 dst.z = (src0.z >= src1.z) ? \sim 0 : 0
1431 dst.w = (src0.w >= src1.w) ? \sim 0 : 0
1434 .. opcode:: ISGE - Signed Integer Set On Greater Equal Than
1438 dst.x = (src0.x >= src1.x) ? \sim 0 : 0
1440 dst.y = (src0.y >= src1.y) ? \sim 0 : 0
1442 dst.z = (src0.z >= src1.z) ? \sim 0 : 0
1444 dst.w = (src0.w >= src1.w) ? \sim 0 : 0
1447 .. opcode:: USGE - Unsigned Integer Set On Greater Equal Than
1451 dst.x = (src0.x >= src1.x) ? \sim 0 : 0
1453 dst.y = (src0.y >= src1.y) ? \sim 0 : 0
1455 dst.z = (src0.z >= src1.z) ? \sim 0 : 0
1457 dst.w = (src0.w >= src1.w) ? \sim 0 : 0
1460 .. opcode:: FSEQ - Float Set On Equal (ordered)
1462 Same comparison as SEQ but returns integer instead of 1.0/0.0 float
1466 dst.x = (src0.x == src1.x) ? \sim 0 : 0
1468 dst.y = (src0.y == src1.y) ? \sim 0 : 0
1470 dst.z = (src0.z == src1.z) ? \sim 0 : 0
1472 dst.w = (src0.w == src1.w) ? \sim 0 : 0
1475 .. opcode:: USEQ - Integer Set On Equal
1479 dst.x = (src0.x == src1.x) ? \sim 0 : 0
1481 dst.y = (src0.y == src1.y) ? \sim 0 : 0
1483 dst.z = (src0.z == src1.z) ? \sim 0 : 0
1485 dst.w = (src0.w == src1.w) ? \sim 0 : 0
1488 .. opcode:: FSNE - Float Set On Not Equal (unordered)
1490 Same comparison as SNE but returns integer instead of 1.0/0.0 float
1494 dst.x = (src0.x != src1.x) ? \sim 0 : 0
1496 dst.y = (src0.y != src1.y) ? \sim 0 : 0
1498 dst.z = (src0.z != src1.z) ? \sim 0 : 0
1500 dst.w = (src0.w != src1.w) ? \sim 0 : 0
1503 .. opcode:: USNE - Integer Set On Not Equal
1507 dst.x = (src0.x != src1.x) ? \sim 0 : 0
1509 dst.y = (src0.y != src1.y) ? \sim 0 : 0
1511 dst.z = (src0.z != src1.z) ? \sim 0 : 0
1513 dst.w = (src0.w != src1.w) ? \sim 0 : 0
1516 .. opcode:: INEG - Integer Negate
1531 .. opcode:: IABS - Integer Absolute Value
1545 These opcodes are used for bit-level manipulation of integers.
1547 .. opcode:: IBFE - Signed Bitfield Extract
1549 See SM5 instruction of the same name. Extracts a set of bits from the input,
1550 and sign-extends them if the high bit of the extracted window is set.
1554 def ibfe(value, offset, bits):
1555 offset = offset & 0x1f
1557 if bits == 0: return 0
1558 # Note: >> sign-extends
1559 if width + offset < 32:
1560 return (value << (32 - offset - bits)) >> (32 - bits)
1562 return value >> offset
1564 .. opcode:: UBFE - Unsigned Bitfield Extract
1566 See SM5 instruction of the same name. Extracts a set of bits from the input,
1567 without any sign-extension.
1571 def ubfe(value, offset, bits):
1572 offset = offset & 0x1f
1574 if bits == 0: return 0
1575 # Note: >> does not sign-extend
1576 if width + offset < 32:
1577 return (value << (32 - offset - bits)) >> (32 - bits)
1579 return value >> offset
1581 .. opcode:: BFI - Bitfield Insert
1583 See SM5 instruction of the same name. Replaces a bit region of 'base' with
1584 the low bits of 'insert'.
1588 def bfi(base, insert, offset, bits):
1589 offset = offset & 0x1f
1591 mask = ((1 << bits) - 1) << offset
1592 return ((insert << offset) & mask) | (base & ~mask)
1594 .. opcode:: BREV - Bitfield Reverse
1596 See SM5 instruction BFREV. Reverses the bits of the argument.
1598 .. opcode:: POPC - Population Count
1600 See SM5 instruction COUNTBITS. Counts the number of set bits in the argument.
1602 .. opcode:: LSB - Index of lowest set bit
1604 See SM5 instruction FIRSTBIT_LO. Computes the 0-based index of the first set
1605 bit of the argument. Returns -1 if none are set.
1607 .. opcode:: IMSB - Index of highest non-sign bit
1609 See SM5 instruction FIRSTBIT_SHI. Computes the 0-based index of the highest
1610 non-sign bit of the argument (i.e. highest 0 bit for negative numbers,
1611 highest 1 bit for positive numbers). Returns -1 if all bits are the same
1612 (i.e. for inputs 0 and -1).
1614 .. opcode:: UMSB - Index of highest set bit
1616 See SM5 instruction FIRSTBIT_HI. Computes the 0-based index of the highest
1617 set bit of the argument. Returns -1 if none are set.
1620 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
1622 These opcodes are only supported in geometry shaders; they have no meaning
1623 in any other type of shader.
1625 .. opcode:: EMIT - Emit
1627 Generate a new vertex for the current primitive into the specified vertex
1628 stream using the values in the output registers.
1631 .. opcode:: ENDPRIM - End Primitive
1633 Complete the current primitive in the specified vertex stream (consisting of
1634 the emitted vertices), and start a new one.
1640 These opcodes are part of :term:`GLSL`'s opcode set. Support for these
1641 opcodes is determined by a special capability bit, ``GLSL``.
1642 Some require glsl version 1.30 (UIF/BREAKC/SWITCH/CASE/DEFAULT/ENDSWITCH).
1644 .. opcode:: CAL - Subroutine Call
1650 .. opcode:: RET - Subroutine Call Return
1655 .. opcode:: CONT - Continue
1657 Unconditionally moves the point of execution to the instruction after the
1658 last bgnloop. The instruction must appear within a bgnloop/endloop.
1662 Support for CONT is determined by a special capability bit,
1663 ``TGSI_CONT_SUPPORTED``. See :ref:`Screen` for more information.
1666 .. opcode:: BGNLOOP - Begin a Loop
1668 Start a loop. Must have a matching endloop.
1671 .. opcode:: BGNSUB - Begin Subroutine
1673 Starts definition of a subroutine. Must have a matching endsub.
1676 .. opcode:: ENDLOOP - End a Loop
1678 End a loop started with bgnloop.
1681 .. opcode:: ENDSUB - End Subroutine
1683 Ends definition of a subroutine.
1686 .. opcode:: NOP - No Operation
1691 .. opcode:: BRK - Break
1693 Unconditionally moves the point of execution to the instruction after the
1694 next endloop or endswitch. The instruction must appear within a loop/endloop
1695 or switch/endswitch.
1698 .. opcode:: BREAKC - Break Conditional
1700 Conditionally moves the point of execution to the instruction after the
1701 next endloop or endswitch. The instruction must appear within a loop/endloop
1702 or switch/endswitch.
1703 Condition evaluates to true if src0.x != 0 where src0.x is interpreted
1704 as an integer register.
1708 Considered for removal as it's quite inconsistent wrt other opcodes
1709 (could emulate with UIF/BRK/ENDIF).
1712 .. opcode:: IF - Float If
1714 Start an IF ... ELSE .. ENDIF block. Condition evaluates to true if
1718 where src0.x is interpreted as a floating point register.
1721 .. opcode:: UIF - Bitwise If
1723 Start an UIF ... ELSE .. ENDIF block. Condition evaluates to true if
1727 where src0.x is interpreted as an integer register.
1730 .. opcode:: ELSE - Else
1732 Starts an else block, after an IF or UIF statement.
1735 .. opcode:: ENDIF - End If
1737 Ends an IF or UIF block.
1740 .. opcode:: SWITCH - Switch
1742 Starts a C-style switch expression. The switch consists of one or multiple
1743 CASE statements, and at most one DEFAULT statement. Execution of a statement
1744 ends when a BRK is hit, but just like in C falling through to other cases
1745 without a break is allowed. Similarly, DEFAULT label is allowed anywhere not
1746 just as last statement, and fallthrough is allowed into/from it.
1747 CASE src arguments are evaluated at bit level against the SWITCH src argument.
1753 (some instructions here)
1756 (some instructions here)
1759 (some instructions here)
1764 .. opcode:: CASE - Switch case
1766 This represents a switch case label. The src arg must be an integer immediate.
1769 .. opcode:: DEFAULT - Switch default
1771 This represents the default case in the switch, which is taken if no other
1775 .. opcode:: ENDSWITCH - End of switch
1777 Ends a switch expression.
1783 The interpolation instructions allow an input to be interpolated in a
1784 different way than its declaration. This corresponds to the GLSL 4.00
1785 interpolateAt* functions. The first argument of each of these must come from
1786 ``TGSI_FILE_INPUT``.
1788 .. opcode:: INTERP_CENTROID - Interpolate at the centroid
1790 Interpolates the varying specified by src0 at the centroid
1792 .. opcode:: INTERP_SAMPLE - Interpolate at the specified sample
1794 Interpolates the varying specified by src0 at the sample id specified by
1795 src1.x (interpreted as an integer)
1797 .. opcode:: INTERP_OFFSET - Interpolate at the specified offset
1799 Interpolates the varying specified by src0 at the offset src1.xy from the
1800 pixel center (interpreted as floats)
1808 The double-precision opcodes reinterpret four-component vectors into
1809 two-component vectors with doubled precision in each component.
1811 .. opcode:: DABS - Absolute
1816 .. opcode:: DADD - Add
1820 dst.xy = src0.xy + src1.xy
1822 dst.zw = src0.zw + src1.zw
1824 .. opcode:: DSEQ - Set on Equal
1828 dst.x = src0.xy == src1.xy ? \sim 0 : 0
1830 dst.z = src0.zw == src1.zw ? \sim 0 : 0
1832 .. opcode:: DSNE - Set on Equal
1836 dst.x = src0.xy != src1.xy ? \sim 0 : 0
1838 dst.z = src0.zw != src1.zw ? \sim 0 : 0
1840 .. opcode:: DSLT - Set on Less than
1844 dst.x = src0.xy < src1.xy ? \sim 0 : 0
1846 dst.z = src0.zw < src1.zw ? \sim 0 : 0
1848 .. opcode:: DSGE - Set on Greater equal
1852 dst.x = src0.xy >= src1.xy ? \sim 0 : 0
1854 dst.z = src0.zw >= src1.zw ? \sim 0 : 0
1856 .. opcode:: DFRAC - Fraction
1860 dst.xy = src.xy - \lfloor src.xy\rfloor
1862 dst.zw = src.zw - \lfloor src.zw\rfloor
1865 .. opcode:: DFRACEXP - Convert Number to Fractional and Integral Components
1867 Like the ``frexp()`` routine in many math libraries, this opcode stores the
1868 exponent of its source to ``dst0``, and the significand to ``dst1``, such that
1869 :math:`dst1 \times 2^{dst0} = src` .
1873 dst0.xy = exp(src.xy)
1875 dst1.xy = frac(src.xy)
1877 dst0.zw = exp(src.zw)
1879 dst1.zw = frac(src.zw)
1881 .. opcode:: DLDEXP - Multiply Number by Integral Power of 2
1883 This opcode is the inverse of :opcode:`DFRACEXP`. The second
1884 source is an integer.
1888 dst.xy = src0.xy \times 2^{src1.x}
1890 dst.zw = src0.zw \times 2^{src1.y}
1892 .. opcode:: DMIN - Minimum
1896 dst.xy = min(src0.xy, src1.xy)
1898 dst.zw = min(src0.zw, src1.zw)
1900 .. opcode:: DMAX - Maximum
1904 dst.xy = max(src0.xy, src1.xy)
1906 dst.zw = max(src0.zw, src1.zw)
1908 .. opcode:: DMUL - Multiply
1912 dst.xy = src0.xy \times src1.xy
1914 dst.zw = src0.zw \times src1.zw
1917 .. opcode:: DMAD - Multiply And Add
1921 dst.xy = src0.xy \times src1.xy + src2.xy
1923 dst.zw = src0.zw \times src1.zw + src2.zw
1926 .. opcode:: DRCP - Reciprocal
1930 dst.xy = \frac{1}{src.xy}
1932 dst.zw = \frac{1}{src.zw}
1934 .. opcode:: DSQRT - Square Root
1938 dst.xy = \sqrt{src.xy}
1940 dst.zw = \sqrt{src.zw}
1942 .. opcode:: DRSQ - Reciprocal Square Root
1946 dst.xy = \frac{1}{\sqrt{src.xy}}
1948 dst.zw = \frac{1}{\sqrt{src.zw}}
1950 .. opcode:: F2D - Float to Double
1954 dst.xy = double(src0.x)
1956 dst.zw = double(src0.y)
1958 .. opcode:: D2F - Double to Float
1962 dst.x = float(src0.xy)
1964 dst.y = float(src0.zw)
1966 .. opcode:: I2D - Int to Double
1970 dst.xy = double(src0.x)
1972 dst.zw = double(src0.y)
1974 .. opcode:: D2I - Double to Int
1978 dst.x = int(src0.xy)
1980 dst.y = int(src0.zw)
1982 .. opcode:: U2D - Unsigned Int to Double
1986 dst.xy = double(src0.x)
1988 dst.zw = double(src0.y)
1990 .. opcode:: D2U - Double to Unsigned Int
1994 dst.x = unsigned(src0.xy)
1996 dst.y = unsigned(src0.zw)
1998 .. _samplingopcodes:
2000 Resource Sampling Opcodes
2001 ^^^^^^^^^^^^^^^^^^^^^^^^^
2003 Those opcodes follow very closely semantics of the respective Direct3D
2004 instructions. If in doubt double check Direct3D documentation.
2005 Note that the swizzle on SVIEW (src1) determines texel swizzling
2010 Using provided address, sample data from the specified texture using the
2011 filtering mode identified by the gven sampler. The source data may come from
2012 any resource type other than buffers.
2014 Syntax: ``SAMPLE dst, address, sampler_view, sampler``
2016 Example: ``SAMPLE TEMP[0], TEMP[1], SVIEW[0], SAMP[0]``
2018 .. opcode:: SAMPLE_I
2020 Simplified alternative to the SAMPLE instruction. Using the provided
2021 integer address, SAMPLE_I fetches data from the specified sampler view
2022 without any filtering. The source data may come from any resource type
2025 Syntax: ``SAMPLE_I dst, address, sampler_view``
2027 Example: ``SAMPLE_I TEMP[0], TEMP[1], SVIEW[0]``
2029 The 'address' is specified as unsigned integers. If the 'address' is out of
2030 range [0...(# texels - 1)] the result of the fetch is always 0 in all
2031 components. As such the instruction doesn't honor address wrap modes, in
2032 cases where that behavior is desirable 'SAMPLE' instruction should be used.
2033 address.w always provides an unsigned integer mipmap level. If the value is
2034 out of the range then the instruction always returns 0 in all components.
2035 address.yz are ignored for buffers and 1d textures. address.z is ignored
2036 for 1d texture arrays and 2d textures.
2038 For 1D texture arrays address.y provides the array index (also as unsigned
2039 integer). If the value is out of the range of available array indices
2040 [0... (array size - 1)] then the opcode always returns 0 in all components.
2041 For 2D texture arrays address.z provides the array index, otherwise it
2042 exhibits the same behavior as in the case for 1D texture arrays. The exact
2043 semantics of the source address are presented in the table below:
2045 +---------------------------+----+-----+-----+---------+
2046 | resource type | X | Y | Z | W |
2047 +===========================+====+=====+=====+=========+
2048 | ``PIPE_BUFFER`` | x | | | ignored |
2049 +---------------------------+----+-----+-----+---------+
2050 | ``PIPE_TEXTURE_1D`` | x | | | mpl |
2051 +---------------------------+----+-----+-----+---------+
2052 | ``PIPE_TEXTURE_2D`` | x | y | | mpl |
2053 +---------------------------+----+-----+-----+---------+
2054 | ``PIPE_TEXTURE_3D`` | x | y | z | mpl |
2055 +---------------------------+----+-----+-----+---------+
2056 | ``PIPE_TEXTURE_RECT`` | x | y | | mpl |
2057 +---------------------------+----+-----+-----+---------+
2058 | ``PIPE_TEXTURE_CUBE`` | not allowed as source |
2059 +---------------------------+----+-----+-----+---------+
2060 | ``PIPE_TEXTURE_1D_ARRAY`` | x | idx | | mpl |
2061 +---------------------------+----+-----+-----+---------+
2062 | ``PIPE_TEXTURE_2D_ARRAY`` | x | y | idx | mpl |
2063 +---------------------------+----+-----+-----+---------+
2065 Where 'mpl' is a mipmap level and 'idx' is the array index.
2067 .. opcode:: SAMPLE_I_MS
2069 Just like SAMPLE_I but allows fetch data from multi-sampled surfaces.
2071 Syntax: ``SAMPLE_I_MS dst, address, sampler_view, sample``
2073 .. opcode:: SAMPLE_B
2075 Just like the SAMPLE instruction with the exception that an additional bias
2076 is applied to the level of detail computed as part of the instruction
2079 Syntax: ``SAMPLE_B dst, address, sampler_view, sampler, lod_bias``
2081 Example: ``SAMPLE_B TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2].x``
2083 .. opcode:: SAMPLE_C
2085 Similar to the SAMPLE instruction but it performs a comparison filter. The
2086 operands to SAMPLE_C are identical to SAMPLE, except that there is an
2087 additional float32 operand, reference value, which must be a register with
2088 single-component, or a scalar literal. SAMPLE_C makes the hardware use the
2089 current samplers compare_func (in pipe_sampler_state) to compare reference
2090 value against the red component value for the surce resource at each texel
2091 that the currently configured texture filter covers based on the provided
2094 Syntax: ``SAMPLE_C dst, address, sampler_view.r, sampler, ref_value``
2096 Example: ``SAMPLE_C TEMP[0], TEMP[1], SVIEW[0].r, SAMP[0], TEMP[2].x``
2098 .. opcode:: SAMPLE_C_LZ
2100 Same as SAMPLE_C, but LOD is 0 and derivatives are ignored. The LZ stands
2103 Syntax: ``SAMPLE_C_LZ dst, address, sampler_view.r, sampler, ref_value``
2105 Example: ``SAMPLE_C_LZ TEMP[0], TEMP[1], SVIEW[0].r, SAMP[0], TEMP[2].x``
2108 .. opcode:: SAMPLE_D
2110 SAMPLE_D is identical to the SAMPLE opcode except that the derivatives for
2111 the source address in the x direction and the y direction are provided by
2114 Syntax: ``SAMPLE_D dst, address, sampler_view, sampler, der_x, der_y``
2116 Example: ``SAMPLE_D TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2], TEMP[3]``
2118 .. opcode:: SAMPLE_L
2120 SAMPLE_L is identical to the SAMPLE opcode except that the LOD is provided
2121 directly as a scalar value, representing no anisotropy.
2123 Syntax: ``SAMPLE_L dst, address, sampler_view, sampler, explicit_lod``
2125 Example: ``SAMPLE_L TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2].x``
2129 Gathers the four texels to be used in a bi-linear filtering operation and
2130 packs them into a single register. Only works with 2D, 2D array, cubemaps,
2131 and cubemaps arrays. For 2D textures, only the addressing modes of the
2132 sampler and the top level of any mip pyramid are used. Set W to zero. It
2133 behaves like the SAMPLE instruction, but a filtered sample is not
2134 generated. The four samples that contribute to filtering are placed into
2135 xyzw in counter-clockwise order, starting with the (u,v) texture coordinate
2136 delta at the following locations (-, +), (+, +), (+, -), (-, -), where the
2137 magnitude of the deltas are half a texel.
2140 .. opcode:: SVIEWINFO
2142 Query the dimensions of a given sampler view. dst receives width, height,
2143 depth or array size and number of mipmap levels as int4. The dst can have a
2144 writemask which will specify what info is the caller interested in.
2146 Syntax: ``SVIEWINFO dst, src_mip_level, sampler_view``
2148 Example: ``SVIEWINFO TEMP[0], TEMP[1].x, SVIEW[0]``
2150 src_mip_level is an unsigned integer scalar. If it's out of range then
2151 returns 0 for width, height and depth/array size but the total number of
2152 mipmap is still returned correctly for the given sampler view. The returned
2153 width, height and depth values are for the mipmap level selected by the
2154 src_mip_level and are in the number of texels. For 1d texture array width
2155 is in dst.x, array size is in dst.y and dst.z is 0. The number of mipmaps is
2156 still in dst.w. In contrast to d3d10 resinfo, there's no way in the tgsi
2157 instruction encoding to specify the return type (float/rcpfloat/uint), hence
2158 always using uint. Also, unlike the SAMPLE instructions, the swizzle on src1
2159 resinfo allowing swizzling dst values is ignored (due to the interaction
2160 with rcpfloat modifier which requires some swizzle handling in the state
2163 .. opcode:: SAMPLE_POS
2165 Query the position of a given sample. dst receives float4 (x, y, 0, 0)
2166 indicated where the sample is located. If the resource is not a multi-sample
2167 resource and not a render target, the result is 0.
2169 .. opcode:: SAMPLE_INFO
2171 dst receives number of samples in x. If the resource is not a multi-sample
2172 resource and not a render target, the result is 0.
2175 .. _resourceopcodes:
2177 Resource Access Opcodes
2178 ^^^^^^^^^^^^^^^^^^^^^^^
2180 .. opcode:: LOAD - Fetch data from a shader resource
2182 Syntax: ``LOAD dst, resource, address``
2184 Example: ``LOAD TEMP[0], RES[0], TEMP[1]``
2186 Using the provided integer address, LOAD fetches data
2187 from the specified buffer or texture without any
2190 The 'address' is specified as a vector of unsigned
2191 integers. If the 'address' is out of range the result
2194 Only the first mipmap level of a resource can be read
2195 from using this instruction.
2197 For 1D or 2D texture arrays, the array index is
2198 provided as an unsigned integer in address.y or
2199 address.z, respectively. address.yz are ignored for
2200 buffers and 1D textures. address.z is ignored for 1D
2201 texture arrays and 2D textures. address.w is always
2204 .. opcode:: STORE - Write data to a shader resource
2206 Syntax: ``STORE resource, address, src``
2208 Example: ``STORE RES[0], TEMP[0], TEMP[1]``
2210 Using the provided integer address, STORE writes data
2211 to the specified buffer or texture.
2213 The 'address' is specified as a vector of unsigned
2214 integers. If the 'address' is out of range the result
2217 Only the first mipmap level of a resource can be
2218 written to using this instruction.
2220 For 1D or 2D texture arrays, the array index is
2221 provided as an unsigned integer in address.y or
2222 address.z, respectively. address.yz are ignored for
2223 buffers and 1D textures. address.z is ignored for 1D
2224 texture arrays and 2D textures. address.w is always
2228 .. _threadsyncopcodes:
2230 Inter-thread synchronization opcodes
2231 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2233 These opcodes are intended for communication between threads running
2234 within the same compute grid. For now they're only valid in compute
2237 .. opcode:: MFENCE - Memory fence
2239 Syntax: ``MFENCE resource``
2241 Example: ``MFENCE RES[0]``
2243 This opcode forces strong ordering between any memory access
2244 operations that affect the specified resource. This means that
2245 previous loads and stores (and only those) will be performed and
2246 visible to other threads before the program execution continues.
2249 .. opcode:: LFENCE - Load memory fence
2251 Syntax: ``LFENCE resource``
2253 Example: ``LFENCE RES[0]``
2255 Similar to MFENCE, but it only affects the ordering of memory loads.
2258 .. opcode:: SFENCE - Store memory fence
2260 Syntax: ``SFENCE resource``
2262 Example: ``SFENCE RES[0]``
2264 Similar to MFENCE, but it only affects the ordering of memory stores.
2267 .. opcode:: BARRIER - Thread group barrier
2271 This opcode suspends the execution of the current thread until all
2272 the remaining threads in the working group reach the same point of
2273 the program. Results are unspecified if any of the remaining
2274 threads terminates or never reaches an executed BARRIER instruction.
2282 These opcodes provide atomic variants of some common arithmetic and
2283 logical operations. In this context atomicity means that another
2284 concurrent memory access operation that affects the same memory
2285 location is guaranteed to be performed strictly before or after the
2286 entire execution of the atomic operation.
2288 For the moment they're only valid in compute programs.
2290 .. opcode:: ATOMUADD - Atomic integer addition
2292 Syntax: ``ATOMUADD dst, resource, offset, src``
2294 Example: ``ATOMUADD TEMP[0], RES[0], TEMP[1], TEMP[2]``
2296 The following operation is performed atomically on each component:
2300 dst_i = resource[offset]_i
2302 resource[offset]_i = dst_i + src_i
2305 .. opcode:: ATOMXCHG - Atomic exchange
2307 Syntax: ``ATOMXCHG dst, resource, offset, src``
2309 Example: ``ATOMXCHG TEMP[0], RES[0], TEMP[1], TEMP[2]``
2311 The following operation is performed atomically on each component:
2315 dst_i = resource[offset]_i
2317 resource[offset]_i = src_i
2320 .. opcode:: ATOMCAS - Atomic compare-and-exchange
2322 Syntax: ``ATOMCAS dst, resource, offset, cmp, src``
2324 Example: ``ATOMCAS TEMP[0], RES[0], TEMP[1], TEMP[2], TEMP[3]``
2326 The following operation is performed atomically on each component:
2330 dst_i = resource[offset]_i
2332 resource[offset]_i = (dst_i == cmp_i ? src_i : dst_i)
2335 .. opcode:: ATOMAND - Atomic bitwise And
2337 Syntax: ``ATOMAND dst, resource, offset, src``
2339 Example: ``ATOMAND TEMP[0], RES[0], TEMP[1], TEMP[2]``
2341 The following operation is performed atomically on each component:
2345 dst_i = resource[offset]_i
2347 resource[offset]_i = dst_i \& src_i
2350 .. opcode:: ATOMOR - Atomic bitwise Or
2352 Syntax: ``ATOMOR dst, resource, offset, src``
2354 Example: ``ATOMOR TEMP[0], RES[0], TEMP[1], TEMP[2]``
2356 The following operation is performed atomically on each component:
2360 dst_i = resource[offset]_i
2362 resource[offset]_i = dst_i | src_i
2365 .. opcode:: ATOMXOR - Atomic bitwise Xor
2367 Syntax: ``ATOMXOR dst, resource, offset, src``
2369 Example: ``ATOMXOR TEMP[0], RES[0], TEMP[1], TEMP[2]``
2371 The following operation is performed atomically on each component:
2375 dst_i = resource[offset]_i
2377 resource[offset]_i = dst_i \oplus src_i
2380 .. opcode:: ATOMUMIN - Atomic unsigned minimum
2382 Syntax: ``ATOMUMIN dst, resource, offset, src``
2384 Example: ``ATOMUMIN TEMP[0], RES[0], TEMP[1], TEMP[2]``
2386 The following operation is performed atomically on each component:
2390 dst_i = resource[offset]_i
2392 resource[offset]_i = (dst_i < src_i ? dst_i : src_i)
2395 .. opcode:: ATOMUMAX - Atomic unsigned maximum
2397 Syntax: ``ATOMUMAX dst, resource, offset, src``
2399 Example: ``ATOMUMAX TEMP[0], RES[0], TEMP[1], TEMP[2]``
2401 The following operation is performed atomically on each component:
2405 dst_i = resource[offset]_i
2407 resource[offset]_i = (dst_i > src_i ? dst_i : src_i)
2410 .. opcode:: ATOMIMIN - Atomic signed minimum
2412 Syntax: ``ATOMIMIN dst, resource, offset, src``
2414 Example: ``ATOMIMIN TEMP[0], RES[0], TEMP[1], TEMP[2]``
2416 The following operation is performed atomically on each component:
2420 dst_i = resource[offset]_i
2422 resource[offset]_i = (dst_i < src_i ? dst_i : src_i)
2425 .. opcode:: ATOMIMAX - Atomic signed maximum
2427 Syntax: ``ATOMIMAX dst, resource, offset, src``
2429 Example: ``ATOMIMAX TEMP[0], RES[0], TEMP[1], TEMP[2]``
2431 The following operation is performed atomically on each component:
2435 dst_i = resource[offset]_i
2437 resource[offset]_i = (dst_i > src_i ? dst_i : src_i)
2441 Explanation of symbols used
2442 ------------------------------
2449 :math:`|x|` Absolute value of `x`.
2451 :math:`\lceil x \rceil` Ceiling of `x`.
2453 clamp(x,y,z) Clamp x between y and z.
2454 (x < y) ? y : (x > z) ? z : x
2456 :math:`\lfloor x\rfloor` Floor of `x`.
2458 :math:`\log_2{x}` Logarithm of `x`, base 2.
2460 max(x,y) Maximum of x and y.
2463 min(x,y) Minimum of x and y.
2466 partialx(x) Derivative of x relative to fragment's X.
2468 partialy(x) Derivative of x relative to fragment's Y.
2470 pop() Pop from stack.
2472 :math:`x^y` `x` to the power `y`.
2474 push(x) Push x on stack.
2478 trunc(x) Truncate x, i.e. drop the fraction bits.
2485 discard Discard fragment.
2489 target Label of target instruction.
2500 Declares a register that is will be referenced as an operand in Instruction
2503 File field contains register file that is being declared and is one
2506 UsageMask field specifies which of the register components can be accessed
2507 and is one of TGSI_WRITEMASK.
2509 The Local flag specifies that a given value isn't intended for
2510 subroutine parameter passing and, as a result, the implementation
2511 isn't required to give any guarantees of it being preserved across
2512 subroutine boundaries. As it's merely a compiler hint, the
2513 implementation is free to ignore it.
2515 If Dimension flag is set to 1, a Declaration Dimension token follows.
2517 If Semantic flag is set to 1, a Declaration Semantic token follows.
2519 If Interpolate flag is set to 1, a Declaration Interpolate token follows.
2521 If file is TGSI_FILE_RESOURCE, a Declaration Resource token follows.
2523 If Array flag is set to 1, a Declaration Array token follows.
2526 ^^^^^^^^^^^^^^^^^^^^^^^^
2528 Declarations can optional have an ArrayID attribute which can be referred by
2529 indirect addressing operands. An ArrayID of zero is reserved and treaded as
2530 if no ArrayID is specified.
2532 If an indirect addressing operand refers to a specific declaration by using
2533 an ArrayID only the registers in this declaration are guaranteed to be
2534 accessed, accessing any register outside this declaration results in undefined
2535 behavior. Note that for compatibility the effective index is zero-based and
2536 not relative to the specified declaration
2538 If no ArrayID is specified with an indirect addressing operand the whole
2539 register file might be accessed by this operand. This is strongly discouraged
2540 and will prevent packing of scalar/vec2 arrays and effective alias analysis.
2542 Declaration Semantic
2543 ^^^^^^^^^^^^^^^^^^^^^^^^
2545 Vertex and fragment shader input and output registers may be labeled
2546 with semantic information consisting of a name and index.
2548 Follows Declaration token if Semantic bit is set.
2550 Since its purpose is to link a shader with other stages of the pipeline,
2551 it is valid to follow only those Declaration tokens that declare a register
2552 either in INPUT or OUTPUT file.
2554 SemanticName field contains the semantic name of the register being declared.
2555 There is no default value.
2557 SemanticIndex is an optional subscript that can be used to distinguish
2558 different register declarations with the same semantic name. The default value
2561 The meanings of the individual semantic names are explained in the following
2564 TGSI_SEMANTIC_POSITION
2565 """"""""""""""""""""""
2567 For vertex shaders, TGSI_SEMANTIC_POSITION indicates the vertex shader
2568 output register which contains the homogeneous vertex position in the clip
2569 space coordinate system. After clipping, the X, Y and Z components of the
2570 vertex will be divided by the W value to get normalized device coordinates.
2572 For fragment shaders, TGSI_SEMANTIC_POSITION is used to indicate that
2573 fragment shader input contains the fragment's window position. The X
2574 component starts at zero and always increases from left to right.
2575 The Y component starts at zero and always increases but Y=0 may either
2576 indicate the top of the window or the bottom depending on the fragment
2577 coordinate origin convention (see TGSI_PROPERTY_FS_COORD_ORIGIN).
2578 The Z coordinate ranges from 0 to 1 to represent depth from the front
2579 to the back of the Z buffer. The W component contains the interpolated
2580 reciprocal of the vertex position W component (corresponding to gl_Fragcoord,
2581 but unlike d3d10 which interpolates the same 1/w but then gives back
2582 the reciprocal of the interpolated value).
2584 Fragment shaders may also declare an output register with
2585 TGSI_SEMANTIC_POSITION. Only the Z component is writable. This allows
2586 the fragment shader to change the fragment's Z position.
2593 For vertex shader outputs or fragment shader inputs/outputs, this
2594 label indicates that the resister contains an R,G,B,A color.
2596 Several shader inputs/outputs may contain colors so the semantic index
2597 is used to distinguish them. For example, color[0] may be the diffuse
2598 color while color[1] may be the specular color.
2600 This label is needed so that the flat/smooth shading can be applied
2601 to the right interpolants during rasterization.
2605 TGSI_SEMANTIC_BCOLOR
2606 """"""""""""""""""""
2608 Back-facing colors are only used for back-facing polygons, and are only valid
2609 in vertex shader outputs. After rasterization, all polygons are front-facing
2610 and COLOR and BCOLOR end up occupying the same slots in the fragment shader,
2611 so all BCOLORs effectively become regular COLORs in the fragment shader.
2617 Vertex shader inputs and outputs and fragment shader inputs may be
2618 labeled with TGSI_SEMANTIC_FOG to indicate that the register contains
2619 a fog coordinate. Typically, the fragment shader will use the fog coordinate
2620 to compute a fog blend factor which is used to blend the normal fragment color
2621 with a constant fog color. But fog coord really is just an ordinary vec4
2622 register like regular semantics.
2628 Vertex shader input and output registers may be labeled with
2629 TGIS_SEMANTIC_PSIZE to indicate that the register contains a point size
2630 in the form (S, 0, 0, 1). The point size controls the width or diameter
2631 of points for rasterization. This label cannot be used in fragment
2634 When using this semantic, be sure to set the appropriate state in the
2635 :ref:`rasterizer` first.
2638 TGSI_SEMANTIC_TEXCOORD
2639 """"""""""""""""""""""
2641 Only available if PIPE_CAP_TGSI_TEXCOORD is exposed !
2643 Vertex shader outputs and fragment shader inputs may be labeled with
2644 this semantic to make them replaceable by sprite coordinates via the
2645 sprite_coord_enable state in the :ref:`rasterizer`.
2646 The semantic index permitted with this semantic is limited to <= 7.
2648 If the driver does not support TEXCOORD, sprite coordinate replacement
2649 applies to inputs with the GENERIC semantic instead.
2651 The intended use case for this semantic is gl_TexCoord.
2654 TGSI_SEMANTIC_PCOORD
2655 """"""""""""""""""""
2657 Only available if PIPE_CAP_TGSI_TEXCOORD is exposed !
2659 Fragment shader inputs may be labeled with TGSI_SEMANTIC_PCOORD to indicate
2660 that the register contains sprite coordinates in the form (x, y, 0, 1), if
2661 the current primitive is a point and point sprites are enabled. Otherwise,
2662 the contents of the register are undefined.
2664 The intended use case for this semantic is gl_PointCoord.
2667 TGSI_SEMANTIC_GENERIC
2668 """""""""""""""""""""
2670 All vertex/fragment shader inputs/outputs not labeled with any other
2671 semantic label can be considered to be generic attributes. Typical
2672 uses of generic inputs/outputs are texcoords and user-defined values.
2675 TGSI_SEMANTIC_NORMAL
2676 """"""""""""""""""""
2678 Indicates that a vertex shader input is a normal vector. This is
2679 typically only used for legacy graphics APIs.
2685 This label applies to fragment shader inputs only and indicates that
2686 the register contains front/back-face information of the form (F, 0,
2687 0, 1). The first component will be positive when the fragment belongs
2688 to a front-facing polygon, and negative when the fragment belongs to a
2689 back-facing polygon.
2692 TGSI_SEMANTIC_EDGEFLAG
2693 """"""""""""""""""""""
2695 For vertex shaders, this sematic label indicates that an input or
2696 output is a boolean edge flag. The register layout is [F, x, x, x]
2697 where F is 0.0 or 1.0 and x = don't care. Normally, the vertex shader
2698 simply copies the edge flag input to the edgeflag output.
2700 Edge flags are used to control which lines or points are actually
2701 drawn when the polygon mode converts triangles/quads/polygons into
2705 TGSI_SEMANTIC_STENCIL
2706 """""""""""""""""""""
2708 For fragment shaders, this semantic label indicates that an output
2709 is a writable stencil reference value. Only the Y component is writable.
2710 This allows the fragment shader to change the fragments stencilref value.
2713 TGSI_SEMANTIC_VIEWPORT_INDEX
2714 """"""""""""""""""""""""""""
2716 For geometry shaders, this semantic label indicates that an output
2717 contains the index of the viewport (and scissor) to use.
2718 This is an integer value, and only the X component is used.
2724 For geometry shaders, this semantic label indicates that an output
2725 contains the layer value to use for the color and depth/stencil surfaces.
2726 This is an integer value, and only the X component is used.
2727 (Also known as rendertarget array index.)
2730 TGSI_SEMANTIC_CULLDIST
2731 """"""""""""""""""""""
2733 Used as distance to plane for performing application-defined culling
2734 of individual primitives against a plane. When components of vertex
2735 elements are given this label, these values are assumed to be a
2736 float32 signed distance to a plane. Primitives will be completely
2737 discarded if the plane distance for all of the vertices in the
2738 primitive are < 0. If a vertex has a cull distance of NaN, that
2739 vertex counts as "out" (as if its < 0);
2740 The limits on both clip and cull distances are bound
2741 by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_COUNT define which defines
2742 the maximum number of components that can be used to hold the
2743 distances and by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT
2744 which specifies the maximum number of registers which can be
2745 annotated with those semantics.
2748 TGSI_SEMANTIC_CLIPDIST
2749 """"""""""""""""""""""
2751 When components of vertex elements are identified this way, these
2752 values are each assumed to be a float32 signed distance to a plane.
2753 Primitive setup only invokes rasterization on pixels for which
2754 the interpolated plane distances are >= 0. Multiple clip planes
2755 can be implemented simultaneously, by annotating multiple
2756 components of one or more vertex elements with the above specified
2757 semantic. The limits on both clip and cull distances are bound
2758 by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_COUNT define which defines
2759 the maximum number of components that can be used to hold the
2760 distances and by the PIPE_MAX_CLIP_OR_CULL_DISTANCE_ELEMENT_COUNT
2761 which specifies the maximum number of registers which can be
2762 annotated with those semantics.
2764 TGSI_SEMANTIC_SAMPLEID
2765 """"""""""""""""""""""
2767 For fragment shaders, this semantic label indicates that a system value
2768 contains the current sample id (i.e. gl_SampleID).
2769 This is an integer value, and only the X component is used.
2771 TGSI_SEMANTIC_SAMPLEPOS
2772 """""""""""""""""""""""
2774 For fragment shaders, this semantic label indicates that a system value
2775 contains the current sample's position (i.e. gl_SamplePosition). Only the X
2776 and Y values are used.
2778 TGSI_SEMANTIC_SAMPLEMASK
2779 """"""""""""""""""""""""
2781 For fragment shaders, this semantic label indicates that an output contains
2782 the sample mask used to disable further sample processing
2783 (i.e. gl_SampleMask). Only the X value is used, up to 32x MS.
2785 TGSI_SEMANTIC_INVOCATIONID
2786 """"""""""""""""""""""""""
2788 For geometry shaders, this semantic label indicates that a system value
2789 contains the current invocation id (i.e. gl_InvocationID).
2790 This is an integer value, and only the X component is used.
2792 TGSI_SEMANTIC_INSTANCEID
2793 """"""""""""""""""""""""
2795 For vertex shaders, this semantic label indicates that a system value contains
2796 the current instance id (i.e. gl_InstanceID). It does not include the base
2797 instance. This is an integer value, and only the X component is used.
2799 TGSI_SEMANTIC_VERTEXID
2800 """"""""""""""""""""""
2802 For vertex shaders, this semantic label indicates that a system value contains
2803 the current vertex id (i.e. gl_VertexID). It does (unlike in d3d10) include the
2804 base vertex. This is an integer value, and only the X component is used.
2806 TGSI_SEMANTIC_VERTEXID_NOBASE
2807 """""""""""""""""""""""""""""""
2809 For vertex shaders, this semantic label indicates that a system value contains
2810 the current vertex id without including the base vertex (this corresponds to
2811 d3d10 vertex id, so TGSI_SEMANTIC_VERTEXID_NOBASE + TGSI_SEMANTIC_BASEVERTEX
2812 == TGSI_SEMANTIC_VERTEXID). This is an integer value, and only the X component
2815 TGSI_SEMANTIC_BASEVERTEX
2816 """"""""""""""""""""""""
2818 For vertex shaders, this semantic label indicates that a system value contains
2819 the base vertex (i.e. gl_BaseVertex). Note that for non-indexed draw calls,
2820 this contains the first (or start) value instead.
2821 This is an integer value, and only the X component is used.
2823 TGSI_SEMANTIC_PRIMID
2824 """"""""""""""""""""
2826 For geometry and fragment shaders, this semantic label indicates the value
2827 contains the primitive id (i.e. gl_PrimitiveID). This is an integer value,
2828 and only the X component is used.
2829 FIXME: This right now can be either a ordinary input or a system value...
2832 Declaration Interpolate
2833 ^^^^^^^^^^^^^^^^^^^^^^^
2835 This token is only valid for fragment shader INPUT declarations.
2837 The Interpolate field specifes the way input is being interpolated by
2838 the rasteriser and is one of TGSI_INTERPOLATE_*.
2840 The Location field specifies the location inside the pixel that the
2841 interpolation should be done at, one of ``TGSI_INTERPOLATE_LOC_*``. Note that
2842 when per-sample shading is enabled, the implementation may choose to
2843 interpolate at the sample irrespective of the Location field.
2845 The CylindricalWrap bitfield specifies which register components
2846 should be subject to cylindrical wrapping when interpolating by the
2847 rasteriser. If TGSI_CYLINDRICAL_WRAP_X is set to 1, the X component
2848 should be interpolated according to cylindrical wrapping rules.
2851 Declaration Sampler View
2852 ^^^^^^^^^^^^^^^^^^^^^^^^
2854 Follows Declaration token if file is TGSI_FILE_SAMPLER_VIEW.
2856 DCL SVIEW[#], resource, type(s)
2858 Declares a shader input sampler view and assigns it to a SVIEW[#]
2861 resource can be one of BUFFER, 1D, 2D, 3D, 1DArray and 2DArray.
2863 type must be 1 or 4 entries (if specifying on a per-component
2864 level) out of UNORM, SNORM, SINT, UINT and FLOAT.
2867 Declaration Resource
2868 ^^^^^^^^^^^^^^^^^^^^
2870 Follows Declaration token if file is TGSI_FILE_RESOURCE.
2872 DCL RES[#], resource [, WR] [, RAW]
2874 Declares a shader input resource and assigns it to a RES[#]
2877 resource can be one of BUFFER, 1D, 2D, 3D, CUBE, 1DArray and
2880 If the RAW keyword is not specified, the texture data will be
2881 subject to conversion, swizzling and scaling as required to yield
2882 the specified data type from the physical data format of the bound
2885 If the RAW keyword is specified, no channel conversion will be
2886 performed: the values read for each of the channels (X,Y,Z,W) will
2887 correspond to consecutive words in the same order and format
2888 they're found in memory. No element-to-address conversion will be
2889 performed either: the value of the provided X coordinate will be
2890 interpreted in byte units instead of texel units. The result of
2891 accessing a misaligned address is undefined.
2893 Usage of the STORE opcode is only allowed if the WR (writable) flag
2898 ^^^^^^^^^^^^^^^^^^^^^^^^
2900 Properties are general directives that apply to the whole TGSI program.
2905 Specifies the fragment shader TGSI_SEMANTIC_POSITION coordinate origin.
2906 The default value is UPPER_LEFT.
2908 If UPPER_LEFT, the position will be (0,0) at the upper left corner and
2909 increase downward and rightward.
2910 If LOWER_LEFT, the position will be (0,0) at the lower left corner and
2911 increase upward and rightward.
2913 OpenGL defaults to LOWER_LEFT, and is configurable with the
2914 GL_ARB_fragment_coord_conventions extension.
2916 DirectX 9/10 use UPPER_LEFT.
2918 FS_COORD_PIXEL_CENTER
2919 """""""""""""""""""""
2921 Specifies the fragment shader TGSI_SEMANTIC_POSITION pixel center convention.
2922 The default value is HALF_INTEGER.
2924 If HALF_INTEGER, the fractionary part of the position will be 0.5
2925 If INTEGER, the fractionary part of the position will be 0.0
2927 Note that this does not affect the set of fragments generated by
2928 rasterization, which is instead controlled by half_pixel_center in the
2931 OpenGL defaults to HALF_INTEGER, and is configurable with the
2932 GL_ARB_fragment_coord_conventions extension.
2934 DirectX 9 uses INTEGER.
2935 DirectX 10 uses HALF_INTEGER.
2937 FS_COLOR0_WRITES_ALL_CBUFS
2938 """"""""""""""""""""""""""
2939 Specifies that writes to the fragment shader color 0 are replicated to all
2940 bound cbufs. This facilitates OpenGL's fragColor output vs fragData[0] where
2941 fragData is directed to a single color buffer, but fragColor is broadcast.
2944 """"""""""""""""""""""""""
2945 If this property is set on the program bound to the shader stage before the
2946 fragment shader, user clip planes should have no effect (be disabled) even if
2947 that shader does not write to any clip distance outputs and the rasterizer's
2948 clip_plane_enable is non-zero.
2949 This property is only supported by drivers that also support shader clip
2951 This is useful for APIs that don't have UCPs and where clip distances written
2952 by a shader cannot be disabled.
2957 Specifies the number of times a geometry shader should be executed for each
2958 input primitive. Each invocation will have a different
2959 TGSI_SEMANTIC_INVOCATIONID system value set. If not specified, assumed to
2962 VS_WINDOW_SPACE_POSITION
2963 """"""""""""""""""""""""""
2964 If this property is set on the vertex shader, the TGSI_SEMANTIC_POSITION output
2965 is assumed to contain window space coordinates.
2966 Division of X,Y,Z by W and the viewport transformation are disabled, and 1/W is
2967 directly taken from the 4-th component of the shader output.
2968 Naturally, clipping is not performed on window coordinates either.
2969 The effect of this property is undefined if a geometry or tessellation shader
2972 Texture Sampling and Texture Formats
2973 ------------------------------------
2975 This table shows how texture image components are returned as (x,y,z,w) tuples
2976 by TGSI texture instructions, such as :opcode:`TEX`, :opcode:`TXD`, and
2977 :opcode:`TXP`. For reference, OpenGL and Direct3D conventions are shown as
2980 +--------------------+--------------+--------------------+--------------+
2981 | Texture Components | Gallium | OpenGL | Direct3D 9 |
2982 +====================+==============+====================+==============+
2983 | R | (r, 0, 0, 1) | (r, 0, 0, 1) | (r, 1, 1, 1) |
2984 +--------------------+--------------+--------------------+--------------+
2985 | RG | (r, g, 0, 1) | (r, g, 0, 1) | (r, g, 1, 1) |
2986 +--------------------+--------------+--------------------+--------------+
2987 | RGB | (r, g, b, 1) | (r, g, b, 1) | (r, g, b, 1) |
2988 +--------------------+--------------+--------------------+--------------+
2989 | RGBA | (r, g, b, a) | (r, g, b, a) | (r, g, b, a) |
2990 +--------------------+--------------+--------------------+--------------+
2991 | A | (0, 0, 0, a) | (0, 0, 0, a) | (0, 0, 0, a) |
2992 +--------------------+--------------+--------------------+--------------+
2993 | L | (l, l, l, 1) | (l, l, l, 1) | (l, l, l, 1) |
2994 +--------------------+--------------+--------------------+--------------+
2995 | LA | (l, l, l, a) | (l, l, l, a) | (l, l, l, a) |
2996 +--------------------+--------------+--------------------+--------------+
2997 | I | (i, i, i, i) | (i, i, i, i) | N/A |
2998 +--------------------+--------------+--------------------+--------------+
2999 | UV | XXX TBD | (0, 0, 0, 1) | (u, v, 1, 1) |
3000 | | | [#envmap-bumpmap]_ | |
3001 +--------------------+--------------+--------------------+--------------+
3002 | Z | XXX TBD | (z, z, z, 1) | (0, z, 0, 1) |
3003 | | | [#depth-tex-mode]_ | |
3004 +--------------------+--------------+--------------------+--------------+
3005 | S | (s, s, s, s) | unknown | unknown |
3006 +--------------------+--------------+--------------------+--------------+
3008 .. [#envmap-bumpmap] http://www.opengl.org/registry/specs/ATI/envmap_bumpmap.txt
3009 .. [#depth-tex-mode] the default is (z, z, z, 1) but may also be (0, 0, 0, z)
3010 or (z, z, z, z) depending on the value of GL_DEPTH_TEXTURE_MODE.