an important part of the API. TGSI is the only intermediate representation
used by all drivers.
+Basics
+------
+
+All TGSI instructions, known as *opcodes*, operate on arbitrary-precision
+floating-point four-component vectors. An opcode may have up to one
+destination register, known as *dst*, and between zero and three source
+registers, called *src0* through *src2*, or simply *src* if there is only
+one.
+
+Some instructions, like :opcode:`I2F`, permit re-interpretation of vector
+components as integers. Other instructions permit using registers as
+two-component vectors with double precision; see :ref:`Double Opcodes`.
+
+When an instruction has a scalar result, the result is usually copied into
+each of the components of *dst*. When this happens, the result is said to be
+*replicated* to *dst*. :opcode:`RCP` is one such instruction.
+
Instruction Set
---------------
-From GL_NV_vertex_program
+Core ISA
^^^^^^^^^^^^^^^^^^^^^^^^^
+These opcodes are guaranteed to be available regardless of the driver being
+used.
-ARL - Address Register Load
+.. opcode:: ARL - Address Register Load
.. math::
dst.w = \lfloor src.w\rfloor
-MOV - Move
+.. opcode:: MOV - Move
.. math::
dst.w = src.w
-LIT - Light Coefficients
+.. opcode:: LIT - Light Coefficients
.. math::
dst.w = 1
-RCP - Reciprocal
-
-.. math::
+.. opcode:: RCP - Reciprocal
- dst.x = \frac{1}{src.x}
+This instruction replicates its result.
- dst.y = \frac{1}{src.x}
+.. math::
- dst.z = \frac{1}{src.x}
+ dst = \frac{1}{src.x}
- dst.w = \frac{1}{src.x}
+.. opcode:: RSQ - Reciprocal Square Root
-RSQ - Reciprocal Square Root
+This instruction replicates its result.
.. math::
- dst.x = \frac{1}{\sqrt{|src.x|}}
-
- dst.y = \frac{1}{\sqrt{|src.x|}}
-
- dst.z = \frac{1}{\sqrt{|src.x|}}
-
- dst.w = \frac{1}{\sqrt{|src.x|}}
+ dst = \frac{1}{\sqrt{|src.x|}}
-EXP - Approximate Exponential Base 2
+.. opcode:: EXP - Approximate Exponential Base 2
.. math::
dst.w = 1
-LOG - Approximate Logarithm Base 2
+.. opcode:: LOG - Approximate Logarithm Base 2
.. math::
dst.w = 1
-MUL - Multiply
+.. opcode:: MUL - Multiply
.. math::
dst.w = src0.w \times src1.w
-ADD - Add
+.. opcode:: ADD - Add
.. math::
dst.w = src0.w + src1.w
-DP3 - 3-component Dot Product
+.. opcode:: DP3 - 3-component Dot Product
-.. math::
-
- dst.x = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z
+This instruction replicates its result.
- dst.y = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z
+.. math::
- dst.z = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z
+ dst = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z
- dst.w = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z
+.. opcode:: DP4 - 4-component Dot Product
-DP4 - 4-component Dot Product
+This instruction replicates its result.
.. math::
- dst.x = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src0.w \times src1.w
-
- dst.y = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src0.w \times src1.w
-
- dst.z = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src0.w \times src1.w
+ dst = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src0.w \times src1.w
- dst.w = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src0.w \times src1.w
-
-DST - Distance Vector
+.. opcode:: DST - Distance Vector
.. math::
dst.w = src1.w
-MIN - Minimum
+.. opcode:: MIN - Minimum
.. math::
dst.w = min(src0.w, src1.w)
-MAX - Maximum
+.. opcode:: MAX - Maximum
.. math::
dst.w = max(src0.w, src1.w)
-SLT - Set On Less Than
+.. opcode:: SLT - Set On Less Than
.. math::
dst.w = (src0.w < src1.w) ? 1 : 0
-SGE - Set On Greater Equal Than
+.. opcode:: SGE - Set On Greater Equal Than
.. math::
dst.w = (src0.w >= src1.w) ? 1 : 0
-MAD - Multiply And Add
+.. opcode:: MAD - Multiply And Add
.. math::
dst.w = src0.w \times src1.w + src2.w
-SUB - Subtract
+.. opcode:: SUB - Subtract
.. math::
dst.w = src0.w - src1.w
-LRP - Linear Interpolate
+.. opcode:: LRP - Linear Interpolate
.. math::
dst.w = src0.w \times src1.w + (1 - src0.w) \times src2.w
-CND - Condition
+.. opcode:: CND - Condition
.. math::
dst.w = (src2.w > 0.5) ? src0.w : src1.w
-DP2A - 2-component Dot Product And Add
+.. opcode:: DP2A - 2-component Dot Product And Add
.. math::
dst.w = src0.x \times src1.x + src0.y \times src1.y + src2.x
-FRAC - Fraction
+.. opcode:: FRC - Fraction
.. math::
dst.w = src.w - \lfloor src.w\rfloor
-CLAMP - Clamp
+.. opcode:: CLAMP - Clamp
.. math::
dst.w = clamp(src0.w, src1.w, src2.w)
-FLR - Floor
+.. opcode:: FLR - Floor
-This is identical to ARL.
+This is identical to :opcode:`ARL`.
.. math::
dst.w = \lfloor src.w\rfloor
-ROUND - Round
+.. opcode:: ROUND - Round
.. math::
dst.w = round(src.w)
-EX2 - Exponential Base 2
-
-.. math::
+.. opcode:: EX2 - Exponential Base 2
- dst.x = 2^{src.x}
+This instruction replicates its result.
- dst.y = 2^{src.x}
+.. math::
- dst.z = 2^{src.x}
+ dst = 2^{src.x}
- dst.w = 2^{src.x}
+.. opcode:: LG2 - Logarithm Base 2
-LG2 - Logarithm Base 2
+This instruction replicates its result.
.. math::
- dst.x = \log_2{src.x}
-
- dst.y = \log_2{src.x}
-
- dst.z = \log_2{src.x}
+ dst = \log_2{src.x}
- dst.w = \log_2{src.x}
+.. opcode:: POW - Power
-POW - Power
+This instruction replicates its result.
.. math::
- dst.x = src0.x^{src1.x}
-
- dst.y = src0.x^{src1.x}
-
- dst.z = src0.x^{src1.x}
+ dst = src0.x^{src1.x}
- dst.w = src0.x^{src1.x}
-
-XPD - Cross Product
+.. opcode:: XPD - Cross Product
.. math::
dst.w = 1
-ABS - Absolute
+.. opcode:: ABS - Absolute
.. math::
dst.w = |src.w|
-RCC - Reciprocal Clamped
+.. opcode:: RCC - Reciprocal Clamped
+
+This instruction replicates its result.
XXX cleanup on aisle three
.. math::
- dst.x = (1 / src.x) > 0 ? clamp(1 / src.x, 5.42101e-020, 1.884467e+019) : clamp(1 / src.x, -1.884467e+019, -5.42101e-020)
-
- dst.y = (1 / src.x) > 0 ? clamp(1 / src.x, 5.42101e-020, 1.884467e+019) : clamp(1 / src.x, -1.884467e+019, -5.42101e-020)
+ dst = (1 / src.x) > 0 ? clamp(1 / src.x, 5.42101e-020, 1.884467e+019) : clamp(1 / src.x, -1.884467e+019, -5.42101e-020)
- dst.z = (1 / src.x) > 0 ? clamp(1 / src.x, 5.42101e-020, 1.884467e+019) : clamp(1 / src.x, -1.884467e+019, -5.42101e-020)
- dst.w = (1 / src.x) > 0 ? clamp(1 / src.x, 5.42101e-020, 1.884467e+019) : clamp(1 / src.x, -1.884467e+019, -5.42101e-020)
+.. opcode:: DPH - Homogeneous Dot Product
-
-DPH - Homogeneous Dot Product
+This instruction replicates its result.
.. math::
- dst.x = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src1.w
-
- dst.y = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src1.w
+ dst = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src1.w
- dst.z = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src1.w
- dst.w = src0.x \times src1.x + src0.y \times src1.y + src0.z \times src1.z + src1.w
+.. opcode:: COS - Cosine
-
-COS - Cosine
+This instruction replicates its result.
.. math::
- dst.x = \cos{src.x}
-
- dst.y = \cos{src.x}
-
- dst.z = \cos{src.x}
-
- dst.w = \cos{src.x}
+ dst = \cos{src.x}
-DDX - Derivative Relative To X
+.. opcode:: DDX - Derivative Relative To X
.. math::
dst.w = partialx(src.w)
-DDY - Derivative Relative To Y
+.. opcode:: DDY - Derivative Relative To Y
.. math::
dst.w = partialy(src.w)
-KILP - Predicated Discard
+.. opcode:: KILP - Predicated Discard
discard
-PK2H - Pack Two 16-bit Floats
+.. opcode:: PK2H - Pack Two 16-bit Floats
TBD
-PK2US - Pack Two Unsigned 16-bit Scalars
+.. opcode:: PK2US - Pack Two Unsigned 16-bit Scalars
TBD
-PK4B - Pack Four Signed 8-bit Scalars
+.. opcode:: PK4B - Pack Four Signed 8-bit Scalars
TBD
-PK4UB - Pack Four Unsigned 8-bit Scalars
+.. opcode:: PK4UB - Pack Four Unsigned 8-bit Scalars
TBD
-RFL - Reflection Vector
+.. opcode:: RFL - Reflection Vector
.. math::
dst.w = 1
-Considered for removal.
+.. note::
+ Considered for removal.
-SEQ - Set On Equal
+
+.. opcode:: SEQ - Set On Equal
.. math::
dst.x = (src0.x == src1.x) ? 1 : 0
+
dst.y = (src0.y == src1.y) ? 1 : 0
+
dst.z = (src0.z == src1.z) ? 1 : 0
+
dst.w = (src0.w == src1.w) ? 1 : 0
-SFL - Set On False
+.. opcode:: SFL - Set On False
+
+This instruction replicates its result.
.. math::
- dst.x = 0
- dst.y = 0
- dst.z = 0
- dst.w = 0
+ dst = 0
+
+.. note::
-Considered for removal.
+ Considered for removal.
-SGT - Set On Greater Than
+
+.. opcode:: SGT - Set On Greater Than
.. math::
dst.x = (src0.x > src1.x) ? 1 : 0
+
dst.y = (src0.y > src1.y) ? 1 : 0
+
dst.z = (src0.z > src1.z) ? 1 : 0
+
dst.w = (src0.w > src1.w) ? 1 : 0
-SIN - Sine
+.. opcode:: SIN - Sine
-.. math::
+This instruction replicates its result.
- dst.x = \sin{src.x}
-
- dst.y = \sin{src.x}
-
- dst.z = \sin{src.x}
+.. math::
- dst.w = \sin{src.x}
+ dst = \sin{src.x}
-SLE - Set On Less Equal Than
+.. opcode:: SLE - Set On Less Equal Than
.. math::
dst.x = (src0.x <= src1.x) ? 1 : 0
+
dst.y = (src0.y <= src1.y) ? 1 : 0
+
dst.z = (src0.z <= src1.z) ? 1 : 0
+
dst.w = (src0.w <= src1.w) ? 1 : 0
-SNE - Set On Not Equal
+.. opcode:: SNE - Set On Not Equal
.. math::
dst.x = (src0.x != src1.x) ? 1 : 0
+
dst.y = (src0.y != src1.y) ? 1 : 0
+
dst.z = (src0.z != src1.z) ? 1 : 0
+
dst.w = (src0.w != src1.w) ? 1 : 0
-STR - Set On True
+.. opcode:: STR - Set On True
+
+This instruction replicates its result.
.. math::
- dst.x = 1
- dst.y = 1
- dst.z = 1
- dst.w = 1
+ dst = 1
-TEX - Texture Lookup
+.. opcode:: TEX - Texture Lookup
- TBD
+.. math::
+ coord = src0
-TXD - Texture Lookup with Derivatives
+ bias = 0.0
- TBD
+ dst = texture_sample(unit, coord, bias)
+ for array textures src0.y contains the slice for 1D,
+ and src0.z contain the slice for 2D.
+ for shadow textures with no arrays, src0.z contains
+ the reference value.
+ for shadow textures with arrays, src0.z contains
+ the reference value for 1D arrays, and src0.w contains
+ the reference value for 2D arrays.
+ There is no way to pass a bias in the .w value for
+ shadow arrays, and GLSL doesn't allow this.
+ GLSL does allow cube shadows maps to take a bias value,
+ and we have to determine how this will look in TGSI.
-TXP - Projective Texture Lookup
+.. opcode:: TXD - Texture Lookup with Derivatives
- TBD
+.. math::
+
+ coord = src0
+
+ ddx = src1
+
+ ddy = src2
+
+ bias = 0.0
+
+ dst = texture_sample_deriv(unit, coord, bias, ddx, ddy)
+
+
+.. opcode:: TXP - Projective Texture Lookup
+
+.. math::
+
+ coord.x = src0.x / src.w
+
+ coord.y = src0.y / src.w
+
+ coord.z = src0.z / src.w
+ coord.w = src0.w
-UP2H - Unpack Two 16-Bit Floats
+ bias = 0.0
+
+ dst = texture_sample(unit, coord, bias)
+
+
+.. opcode:: UP2H - Unpack Two 16-Bit Floats
TBD
- Considered for removal.
+.. note::
-UP2US - Unpack Two Unsigned 16-Bit Scalars
+ Considered for removal.
+
+.. opcode:: UP2US - Unpack Two Unsigned 16-Bit Scalars
TBD
- Considered for removal.
+.. note::
+
+ Considered for removal.
-UP4B - Unpack Four Signed 8-Bit Values
+.. opcode:: UP4B - Unpack Four Signed 8-Bit Values
TBD
- Considered for removal.
+.. note::
-UP4UB - Unpack Four Unsigned 8-Bit Scalars
+ Considered for removal.
+
+.. opcode:: UP4UB - Unpack Four Unsigned 8-Bit Scalars
TBD
- Considered for removal.
+.. note::
+
+ Considered for removal.
-X2D - 2D Coordinate Transformation
+.. opcode:: X2D - 2D Coordinate Transformation
.. math::
dst.x = src0.x + src1.x \times src2.x + src1.y \times src2.y
+
dst.y = src0.y + src1.x \times src2.z + src1.y \times src2.w
+
dst.z = src0.x + src1.x \times src2.x + src1.y \times src2.y
- dst.w = src0.y + src1.x \times src2.z + src1.y \times src2.w
-Considered for removal.
+ dst.w = src0.y + src1.x \times src2.z + src1.y \times src2.w
+.. note::
-From GL_NV_vertex_program2
-^^^^^^^^^^^^^^^^^^^^^^^^^^
+ Considered for removal.
-ARA - Address Register Add
+.. opcode:: ARA - Address Register Add
TBD
- Considered for removal.
+.. note::
+
+ Considered for removal.
-ARR - Address Register Load With Round
+.. opcode:: ARR - Address Register Load With Round
.. math::
dst.w = round(src.w)
-BRA - Branch
+.. opcode:: BRA - Branch
pc = target
- Considered for removal.
+.. note::
+
+ Considered for removal.
-CAL - Subroutine Call
+.. opcode:: CAL - Subroutine Call
push(pc)
pc = target
-RET - Subroutine Call Return
+.. opcode:: RET - Subroutine Call Return
pc = pop()
- Potential restrictions:
- * Only occurs at end of function.
-SSG - Set Sign
+.. opcode:: SSG - Set Sign
.. math::
dst.w = (src.w > 0) ? 1 : (src.w < 0) ? -1 : 0
-CMP - Compare
+.. opcode:: CMP - Compare
.. math::
dst.w = (src0.w < 0) ? src1.w : src2.w
-KIL - Conditional Discard
+.. opcode:: KIL - Conditional Discard
.. math::
endif
-SCS - Sine Cosine
+.. opcode:: SCS - Sine Cosine
.. math::
dst.z = 0
- dst.y = 1
+ dst.w = 1
-TXB - Texture Lookup With Bias
+.. opcode:: TXB - Texture Lookup With Bias
- TBD
+.. math::
+
+ coord.x = src.x
+
+ coord.y = src.y
+
+ coord.z = src.z
+ coord.w = 1.0
-NRM - 3-component Vector Normalise
+ bias = src.z
+
+ dst = texture_sample(unit, coord, bias)
+
+
+.. opcode:: NRM - 3-component Vector Normalise
.. math::
dst.w = 1
-DIV - Divide
+.. opcode:: DIV - Divide
.. math::
dst.w = \frac{src0.w}{src1.w}
-DP2 - 2-component Dot Product
-
-.. math::
-
- dst.x = src0.x \times src1.x + src0.y \times src1.y
-
- dst.y = src0.x \times src1.x + src0.y \times src1.y
-
- dst.z = src0.x \times src1.x + src0.y \times src1.y
-
- dst.w = src0.x \times src1.x + src0.y \times src1.y
-
+.. opcode:: DP2 - 2-component Dot Product
-TXL - Texture Lookup With LOD
+This instruction replicates its result.
- TBD
-
-
-BRK - Break
+.. math::
- TBD
+ dst = src0.x \times src1.x + src0.y \times src1.y
-IF - If
+.. opcode:: TXL - Texture Lookup With explicit LOD
- TBD
+.. math::
+ coord.x = src0.x
-BGNFOR - Begin a For-Loop
+ coord.y = src0.y
- dst.x = floor(src.x)
- dst.y = floor(src.y)
- dst.z = floor(src.z)
+ coord.z = src0.z
- if (dst.y <= 0)
- pc = [matching ENDFOR] + 1
- endif
+ coord.w = 1.0
- Note: The destination must be a loop register.
- The source must be a constant register.
+ lod = src0.w
- Considered for cleanup / removal.
+ dst = texture_sample(unit, coord, lod)
-REP - Repeat
+.. opcode:: BRK - Break
TBD
-ELSE - Else
+.. opcode:: IF - If
TBD
-ENDIF - End If
+.. opcode:: ELSE - Else
TBD
-ENDFOR - End a For-Loop
-
- dst.x = dst.x + dst.z
- dst.y = dst.y - 1.0
-
- if (dst.y > 0)
- pc = [matching BGNFOR instruction] + 1
- endif
-
- Note: The destination must be a loop register.
-
- Considered for cleanup / removal.
-
-ENDREP - End Repeat
+.. opcode:: ENDIF - End If
TBD
-PUSHA - Push Address Register On Stack
+.. opcode:: PUSHA - Push Address Register On Stack
push(src.x)
push(src.y)
push(src.z)
push(src.w)
- Considered for cleanup / removal.
+.. note::
-POPA - Pop Address Register From Stack
+ Considered for cleanup.
+
+.. note::
+
+ Considered for removal.
+
+.. opcode:: POPA - Pop Address Register From Stack
dst.w = pop()
dst.z = pop()
dst.y = pop()
dst.x = pop()
- Considered for cleanup / removal.
+.. note::
+
+ Considered for cleanup.
+
+.. note::
+ Considered for removal.
-From GL_NV_gpu_program4
+
+Compute ISA
^^^^^^^^^^^^^^^^^^^^^^^^
+These opcodes are primarily provided for special-use computational shaders.
Support for these opcodes indicated by a special pipe capability bit (TBD).
-CEIL - Ceiling
+XXX so let's discuss it, yeah?
+
+.. opcode:: CEIL - Ceiling
.. math::
dst.w = \lceil src.w\rceil
-I2F - Integer To Float
+.. opcode:: I2F - Integer To Float
.. math::
dst.w = (float) src.w
-NOT - Bitwise Not
+.. opcode:: NOT - Bitwise Not
.. math::
dst.w = ~src.w
-TRUNC - Truncate
-
-XXX how is this different from floor?
+.. opcode:: TRUNC - Truncate
.. math::
dst.w = trunc(src.w)
-SHL - Shift Left
+.. opcode:: SHL - Shift Left
.. math::
dst.w = src0.w << src1.x
-SHR - Shift Right
+.. opcode:: SHR - Shift Right
.. math::
dst.w = src0.w >> src1.x
-AND - Bitwise And
+.. opcode:: AND - Bitwise And
.. math::
dst.w = src0.w & src1.w
-OR - Bitwise Or
+.. opcode:: OR - Bitwise Or
.. math::
dst.w = src0.w | src1.w
-MOD - Modulus
+.. opcode:: MOD - Modulus
.. math::
dst.w = src0.w \bmod src1.w
-XOR - Bitwise Xor
+.. opcode:: XOR - Bitwise Xor
+
+.. math::
+
+ dst.x = src0.x \oplus src1.x
+
+ dst.y = src0.y \oplus src1.y
+
+ dst.z = src0.z \oplus src1.z
+
+ dst.w = src0.w \oplus src1.w
+
+
+.. opcode:: UCMP - Integer Conditional Move
.. math::
- dst.x = src0.x ^ src1.x
+ dst.x = src0.x ? src1.x : src2.x
+
+ dst.y = src0.y ? src1.y : src2.y
+
+ dst.z = src0.z ? src1.z : src2.z
+
+ dst.w = src0.w ? src1.w : src2.w
- dst.y = src0.y ^ src1.y
- dst.z = src0.z ^ src1.z
+.. opcode:: UARL - Integer Address Register Load
- dst.w = src0.w ^ src1.w
+ Moves the contents of the source register, assumed to be an integer, into the
+ destination register, which is assumed to be an address (ADDR) register.
-SAD - Sum Of Absolute Differences
+.. opcode:: IABS - Integer Absolute Value
+
+.. math::
+
+ dst.x = |src.x|
+
+ dst.y = |src.y|
+
+ dst.z = |src.z|
+
+ dst.w = |src.w|
+
+
+.. opcode:: SAD - Sum Of Absolute Differences
.. math::
dst.w = |src0.w - src1.w| + src2.w
-TXF - Texel Fetch
+.. opcode:: TXF - Texel Fetch (as per NV_gpu_shader4), extract a single texel
+ from a specified texture image. The source sampler may
+ not be a CUBE or SHADOW.
+ src 0 is a four-component signed integer vector used to
+ identify the single texel accessed. 3 components + level.
+ src 1 is a 3 component constant signed integer vector,
+ with each component only have a range of
+ -8..+8 (hw only seems to deal with this range, interface
+ allows for up to unsigned int).
+ TXF(uint_vec coord, int_vec offset).
- TBD
+.. opcode:: TXQ - Texture Size Query (as per NV_gpu_program4)
+ retrieve the dimensions of the texture
+ depending on the target. For 1D (width), 2D/RECT/CUBE
+ (width, height), 3D (width, height, depth),
+ 1D array (width, layers), 2D array (width, height, layers)
+
+.. math::
-TXQ - Texture Size Query
+ lod = src0
- TBD
+ dst.x = texture_width(unit, lod)
+
+ dst.y = texture_height(unit, lod)
+ dst.z = texture_depth(unit, lod)
-CONT - Continue
+
+.. opcode:: CONT - Continue
TBD
+.. note::
+
+ Support for CONT is determined by a special capability bit,
+ ``TGSI_CONT_SUPPORTED``. See :ref:`Screen` for more information.
-From GL_NV_geometry_program4
+
+Geometry ISA
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+These opcodes are only supported in geometry shaders; they have no meaning
+in any other type of shader.
-EMIT - Emit
+.. opcode:: EMIT - Emit
TBD
-ENDPRIM - End Primitive
+.. opcode:: ENDPRIM - End Primitive
TBD
-From GLSL
+GLSL ISA
^^^^^^^^^^
+These opcodes are part of :term:`GLSL`'s opcode set. Support for these
+opcodes is determined by a special capability bit, ``GLSL``.
-BGNLOOP - Begin a Loop
+.. opcode:: BGNLOOP - Begin a Loop
TBD
-BGNSUB - Begin Subroutine
+.. opcode:: BGNSUB - Begin Subroutine
TBD
-ENDLOOP - End a Loop
+.. opcode:: ENDLOOP - End a Loop
TBD
-ENDSUB - End Subroutine
+.. opcode:: ENDSUB - End Subroutine
TBD
+.. opcode:: NOP - No Operation
-NOP - No Operation
-
- Do nothing.
+ Do nothing.
-NRM4 - 4-component Vector Normalise
-.. math::
+.. opcode:: NRM4 - 4-component Vector Normalise
- dst.x = \frac{src.x}{src.x \times src.x + src.y \times src.y + src.z \times src.z + src.w \times src.w}
+This instruction replicates its result.
- dst.y = \frac{src.y}{src.x \times src.x + src.y \times src.y + src.z \times src.z + src.w \times src.w}
-
- dst.z = \frac{src.z}{src.x \times src.x + src.y \times src.y + src.z \times src.z + src.w \times src.w}
+.. math::
- dst.w = \frac{src.w}{src.x \times src.x + src.y \times src.y + src.z \times src.z + src.w \times src.w}
+ dst = \frac{src.x}{src.x \times src.x + src.y \times src.y + src.z \times src.z + src.w \times src.w}
ps_2_x
^^^^^^^^^^^^
+XXX wait what
-CALLNZ - Subroutine Call If Not Zero
+.. opcode:: CALLNZ - Subroutine Call If Not Zero
TBD
-IFC - If
+.. opcode:: IFC - If
TBD
-BREAKC - Break Conditional
+.. opcode:: BREAKC - Break Conditional
TBD
+.. _doubleopcodes:
+
+Double ISA
+^^^^^^^^^^^^^^^
+
+The double-precision opcodes reinterpret four-component vectors into
+two-component vectors with doubled precision in each component.
+
+Support for these opcodes is XXX undecided. :T
+
+.. opcode:: DADD - Add
+
+.. math::
+
+ dst.xy = src0.xy + src1.xy
+
+ dst.zw = src0.zw + src1.zw
+
+
+.. opcode:: DDIV - Divide
+
+.. math::
+
+ dst.xy = src0.xy / src1.xy
+
+ dst.zw = src0.zw / src1.zw
+
+.. opcode:: DSEQ - Set on Equal
+
+.. math::
+
+ dst.xy = src0.xy == src1.xy ? 1.0F : 0.0F
+
+ dst.zw = src0.zw == src1.zw ? 1.0F : 0.0F
+
+.. opcode:: DSLT - Set on Less than
+
+.. math::
+
+ dst.xy = src0.xy < src1.xy ? 1.0F : 0.0F
+
+ dst.zw = src0.zw < src1.zw ? 1.0F : 0.0F
+
+.. opcode:: DFRAC - Fraction
+
+.. math::
+
+ dst.xy = src.xy - \lfloor src.xy\rfloor
+
+ dst.zw = src.zw - \lfloor src.zw\rfloor
+
+
+.. opcode:: DFRACEXP - Convert Number to Fractional and Integral Components
+
+Like the ``frexp()`` routine in many math libraries, this opcode stores the
+exponent of its source to ``dst0``, and the significand to ``dst1``, such that
+:math:`dst1 \times 2^{dst0} = src` .
+
+.. math::
+
+ dst0.xy = exp(src.xy)
+
+ dst1.xy = frac(src.xy)
+
+ dst0.zw = exp(src.zw)
+
+ dst1.zw = frac(src.zw)
+
+.. opcode:: DLDEXP - Multiply Number by Integral Power of 2
+
+This opcode is the inverse of :opcode:`DFRACEXP`.
+
+.. math::
+
+ dst.xy = src0.xy \times 2^{src1.xy}
+
+ dst.zw = src0.zw \times 2^{src1.zw}
+
+.. opcode:: DMIN - Minimum
+
+.. math::
+
+ dst.xy = min(src0.xy, src1.xy)
+
+ dst.zw = min(src0.zw, src1.zw)
+
+.. opcode:: DMAX - Maximum
+
+.. math::
+
+ dst.xy = max(src0.xy, src1.xy)
+
+ dst.zw = max(src0.zw, src1.zw)
+
+.. opcode:: DMUL - Multiply
+
+.. math::
+
+ dst.xy = src0.xy \times src1.xy
+
+ dst.zw = src0.zw \times src1.zw
+
+
+.. opcode:: DMAD - Multiply And Add
+
+.. math::
+
+ dst.xy = src0.xy \times src1.xy + src2.xy
+
+ dst.zw = src0.zw \times src1.zw + src2.zw
+
+
+.. opcode:: DRCP - Reciprocal
+
+.. math::
+
+ dst.xy = \frac{1}{src.xy}
+
+ dst.zw = \frac{1}{src.zw}
+
+.. opcode:: DSQRT - Square Root
+
+.. math::
+
+ dst.xy = \sqrt{src.xy}
+
+ dst.zw = \sqrt{src.zw}
+
+
+.. _samplingopcodes:
+
+Resource Sampling Opcodes
+^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Those opcodes follow very closely semantics of the respective Direct3D
+instructions. If in doubt double check Direct3D documentation.
+
+.. opcode:: SAMPLE - Using provided address, sample data from the
+ specified texture using the filtering mode identified
+ by the gven sampler. The source data may come from
+ any resource type other than buffers.
+ SAMPLE dst, address, sampler_view, sampler
+ e.g.
+ SAMPLE TEMP[0], TEMP[1], SVIEW[0], SAMP[0]
+
+.. opcode:: SAMPLE_I - Simplified alternative to the SAMPLE instruction.
+ Using the provided integer address, SAMPLE_I fetches data
+ from the specified sampler view without any filtering.
+ The source data may come from any resource type other
+ than CUBE.
+ SAMPLE_I dst, address, sampler_view
+ e.g.
+ SAMPLE_I TEMP[0], TEMP[1], SVIEW[0]
+ The 'address' is specified as unsigned integers. If the
+ 'address' is out of range [0...(# texels - 1)] the
+ result of the fetch is always 0 in all components.
+ As such the instruction doesn't honor address wrap
+ modes, in cases where that behavior is desirable
+ 'SAMPLE' instruction should be used.
+ address.w always provides an unsigned integer mipmap
+ level. If the value is out of the range then the
+ instruction always returns 0 in all components.
+ address.yz are ignored for buffers and 1d textures.
+ address.z is ignored for 1d texture arrays and 2d
+ textures.
+ For 1D texture arrays address.y provides the array
+ index (also as unsigned integer). If the value is
+ out of the range of available array indices
+ [0... (array size - 1)] then the opcode always returns
+ 0 in all components.
+ For 2D texture arrays address.z provides the array
+ index, otherwise it exhibits the same behavior as in
+ the case for 1D texture arrays.
+ The exact semantics of the source address are presented
+ in the table below:
+ resource type X Y Z W
+ ------------- ------------------------
+ PIPE_BUFFER x ignored
+ PIPE_TEXTURE_1D x mpl
+ PIPE_TEXTURE_2D x y mpl
+ PIPE_TEXTURE_3D x y z mpl
+ PIPE_TEXTURE_RECT x y mpl
+ PIPE_TEXTURE_CUBE not allowed as source
+ PIPE_TEXTURE_1D_ARRAY x idx mpl
+ PIPE_TEXTURE_2D_ARRAY x y idx mpl
+
+ Where 'mpl' is a mipmap level and 'idx' is the
+ array index.
+
+.. opcode:: SAMPLE_I_MS - Just like SAMPLE_I but allows fetch data from
+ multi-sampled surfaces.
+
+.. opcode:: SAMPLE_B - Just like the SAMPLE instruction with the
+ exception that an additiona bias is applied to the
+ level of detail computed as part of the instruction
+ execution.
+ SAMPLE_B dst, address, sampler_view, sampler, lod_bias
+ e.g.
+ SAMPLE_B TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2].x
+
+.. opcode:: SAMPLE_C - Similar to the SAMPLE instruction but it
+ performs a comparison filter. The operands to SAMPLE_C
+ are identical to SAMPLE, except that tere is an additional
+ float32 operand, reference value, which must be a register
+ with single-component, or a scalar literal.
+ SAMPLE_C makes the hardware use the current samplers
+ compare_func (in pipe_sampler_state) to compare
+ reference value against the red component value for the
+ surce resource at each texel that the currently configured
+ texture filter covers based on the provided coordinates.
+ SAMPLE_C dst, address, sampler_view.r, sampler, ref_value
+ e.g.
+ SAMPLE_C TEMP[0], TEMP[1], SVIEW[0].r, SAMP[0], TEMP[2].x
+
+.. opcode:: SAMPLE_C_LZ - Same as SAMPLE_C, but LOD is 0 and derivatives
+ are ignored. The LZ stands for level-zero.
+ SAMPLE_C_LZ dst, address, sampler_view.r, sampler, ref_value
+ e.g.
+ SAMPLE_C_LZ TEMP[0], TEMP[1], SVIEW[0].r, SAMP[0], TEMP[2].x
+
+
+.. opcode:: SAMPLE_D - SAMPLE_D is identical to the SAMPLE opcode except
+ that the derivatives for the source address in the x
+ direction and the y direction are provided by extra
+ parameters.
+ SAMPLE_D dst, address, sampler_view, sampler, der_x, der_y
+ e.g.
+ SAMPLE_D TEMP[0], TEMP[1], SVIEW[0], SAMP[0], TEMP[2], TEMP[3]
+
+.. opcode:: SAMPLE_L - SAMPLE_L is identical to the SAMPLE opcode except
+ that the LOD is provided directly as a scalar value,
+ representing no anisotropy. Source addresses A channel
+ is used as the LOD.
+ SAMPLE_L dst, address, sampler_view, sampler
+ e.g.
+ SAMPLE_L TEMP[0], TEMP[1], SVIEW[0], SAMP[0]
+
+.. opcode:: GATHER4 - Gathers the four texels to be used in a bi-linear
+ filtering operation and packs them into a single register.
+ Only works with 2D, 2D array, cubemaps, and cubemaps arrays.
+ For 2D textures, only the addressing modes of the sampler and
+ the top level of any mip pyramid are used. Set W to zero.
+ It behaves like the SAMPLE instruction, but a filtered
+ sample is not generated. The four samples that contribute
+ to filtering are placed into xyzw in counter-clockwise order,
+ starting with the (u,v) texture coordinate delta at the
+ following locations (-, +), (+, +), (+, -), (-, -), where
+ the magnitude of the deltas are half a texel.
+
+
+.. opcode:: SVIEWINFO - query the dimensions of a given sampler view.
+ dst receives width, height, depth or array size and
+ number of mipmap levels. The dst can have a writemask
+ which will specify what info is the caller interested
+ in.
+ SVIEWINFO dst, src_mip_level, sampler_view
+ e.g.
+ SVIEWINFO TEMP[0], TEMP[1].x, SVIEW[0]
+ src_mip_level is an unsigned integer scalar. If it's
+ out of range then returns 0 for width, height and
+ depth/array size but the total number of mipmap is
+ still returned correctly for the given sampler view.
+ The returned width, height and depth values are for
+ the mipmap level selected by the src_mip_level and
+ are in the number of texels.
+ For 1d texture array width is in dst.x, array size
+ is in dst.y and dst.zw are always 0.
+
+.. opcode:: SAMPLE_POS - query the position of a given sample.
+ dst receives float4 (x, y, 0, 0) indicated where the
+ sample is located. If the resource is not a multi-sample
+ resource and not a render target, the result is 0.
+
+.. opcode:: SAMPLE_INFO - dst receives number of samples in x.
+ If the resource is not a multi-sample resource and
+ not a render target, the result is 0.
+
+
+.. _resourceopcodes:
+
+Resource Access Opcodes
+^^^^^^^^^^^^^^^^^^^^^^^
+
+.. opcode:: LOAD - Fetch data from a shader resource
+
+ Syntax: ``LOAD dst, resource, address``
+
+ Example: ``LOAD TEMP[0], RES[0], TEMP[1]``
+
+ Using the provided integer address, LOAD fetches data
+ from the specified buffer or texture without any
+ filtering.
+
+ The 'address' is specified as a vector of unsigned
+ integers. If the 'address' is out of range the result
+ is unspecified.
+
+ Only the first mipmap level of a resource can be read
+ from using this instruction.
+
+ For 1D or 2D texture arrays, the array index is
+ provided as an unsigned integer in address.y or
+ address.z, respectively. address.yz are ignored for
+ buffers and 1D textures. address.z is ignored for 1D
+ texture arrays and 2D textures. address.w is always
+ ignored.
+
Explanation of symbols used
------------------------------
round(x) Round x.
- trunc(x) Truncate x.
+ trunc(x) Truncate x, i.e. drop the fraction bits.
Keywords
discard Discard fragment.
- dst First destination register.
+ pc Program counter.
- dst0 First destination register.
+ target Label of target instruction.
- pc Program counter.
- src First source register.
+Other tokens
+---------------
- src0 First source register.
- src1 Second source register.
+Declaration
+^^^^^^^^^^^
- src2 Third source register.
- target Label of target instruction.
+Declares a register that is will be referenced as an operand in Instruction
+tokens.
+File field contains register file that is being declared and is one
+of TGSI_FILE.
-Other tokens
----------------
+UsageMask field specifies which of the register components can be accessed
+and is one of TGSI_WRITEMASK.
+
+If Dimension flag is set to 1, a Declaration Dimension token follows.
+
+If Semantic flag is set to 1, a Declaration Semantic token follows.
+
+If Interpolate flag is set to 1, a Declaration Interpolate token follows.
+
+If file is TGSI_FILE_RESOURCE, a Declaration Resource token follows.
Declaration Semantic
^^^^^^^^^^^^^^^^^^^^^^^^
+ Vertex and fragment shader input and output registers may be labeled
+ with semantic information consisting of a name and index.
Follows Declaration token if Semantic bit is set.
TGSI_SEMANTIC_POSITION
""""""""""""""""""""""
-Position, sometimes known as HPOS or WPOS for historical reasons, is the
-location of the vertex in space, in ``(x, y, z, w)`` format. ``x``, ``y``, and ``z``
-are the Cartesian coordinates, and ``w`` is the homogenous coordinate and used
-for the perspective divide, if enabled.
-
-As a vertex shader output, position should be scaled to the viewport. When
-used in fragment shaders, position will ---
+For vertex shaders, TGSI_SEMANTIC_POSITION indicates the vertex shader
+output register which contains the homogeneous vertex position in the clip
+space coordinate system. After clipping, the X, Y and Z components of the
+vertex will be divided by the W value to get normalized device coordinates.
-XXX --- wait a minute. Should position be in [0,1] for x and y?
+For fragment shaders, TGSI_SEMANTIC_POSITION is used to indicate that
+fragment shader input contains the fragment's window position. The X
+component starts at zero and always increases from left to right.
+The Y component starts at zero and always increases but Y=0 may either
+indicate the top of the window or the bottom depending on the fragment
+coordinate origin convention (see TGSI_PROPERTY_FS_COORD_ORIGIN).
+The Z coordinate ranges from 0 to 1 to represent depth from the front
+to the back of the Z buffer. The W component contains the reciprocol
+of the interpolated vertex position W component.
-XXX additionally, is there a way to configure the perspective divide? it's
-accelerated on most chipsets AFAIK...
+Fragment shaders may also declare an output register with
+TGSI_SEMANTIC_POSITION. Only the Z component is writable. This allows
+the fragment shader to change the fragment's Z position.
-Position, if not specified, usually defaults to ``(0, 0, 0, 1)``, and can
-be partially specified as ``(x, y, 0, 1)`` or ``(x, y, z, 1)``.
-XXX usually? can we solidify that?
TGSI_SEMANTIC_COLOR
"""""""""""""""""""
-Colors are used to, well, color the primitives. Colors are always in
-``(r, g, b, a)`` format.
+For vertex shader outputs or fragment shader inputs/outputs, this
+label indicates that the resister contains an R,G,B,A color.
+
+Several shader inputs/outputs may contain colors so the semantic index
+is used to distinguish them. For example, color[0] may be the diffuse
+color while color[1] may be the specular color.
+
+This label is needed so that the flat/smooth shading can be applied
+to the right interpolants during rasterization.
+
-If alpha is not specified, it defaults to 1.
TGSI_SEMANTIC_BCOLOR
""""""""""""""""""""
Back-facing colors are only used for back-facing polygons, and are only valid
in vertex shader outputs. After rasterization, all polygons are front-facing
-and COLOR and BCOLOR end up occupying the same slots in the fragment, so
-all BCOLORs effectively become regular COLORs in the fragment shader.
+and COLOR and BCOLOR end up occupying the same slots in the fragment shader,
+so all BCOLORs effectively become regular COLORs in the fragment shader.
+
TGSI_SEMANTIC_FOG
"""""""""""""""""
-The fog coordinate historically has been used to replace the depth coordinate
-for generation of fog in dedicated fog blocks. Gallium, however, does not use
-dedicated fog acceleration, placing it entirely in the fragment shader
-instead.
+Vertex shader inputs and outputs and fragment shader inputs may be
+labeled with TGSI_SEMANTIC_FOG to indicate that the register contains
+a fog coordinate in the form (F, 0, 0, 1). Typically, the fragment
+shader will use the fog coordinate to compute a fog blend factor which
+is used to blend the normal fragment color with a constant fog color.
+
+Only the first component matters when writing from the vertex shader;
+the driver will ensure that the coordinate is in this format when used
+as a fragment shader input.
-The fog coordinate should be written in ``(f, 0, 0, 1)`` format. Only the first
-component matters when writing from the vertex shader; the driver will ensure
-that the coordinate is in this format when used as a fragment shader input.
TGSI_SEMANTIC_PSIZE
"""""""""""""""""""
-PSIZE, or point size, is used to specify point sizes per-vertex. It should
-be in ``(p, n, x, f)`` format, where ``p`` is the point size, ``n`` is the minimum
-size, ``x`` is the maximum size, and ``f`` is the fade threshold.
-
-XXX this is arb_vp. is this what we actually do? should double-check...
+Vertex shader input and output registers may be labeled with
+TGIS_SEMANTIC_PSIZE to indicate that the register contains a point size
+in the form (S, 0, 0, 1). The point size controls the width or diameter
+of points for rasterization. This label cannot be used in fragment
+shaders.
When using this semantic, be sure to set the appropriate state in the
:ref:`rasterizer` first.
+
TGSI_SEMANTIC_GENERIC
"""""""""""""""""""""
-Generic semantics are nearly always used for texture coordinate attributes,
-in ``(s, t, r, q)`` format. ``t`` and ``r`` may be unused for certain kinds
-of lookups, and ``q`` is the level-of-detail bias for biased sampling.
+All vertex/fragment shader inputs/outputs not labeled with any other
+semantic label can be considered to be generic attributes. Typical
+uses of generic inputs/outputs are texcoords and user-defined values.
-These attributes are called "generic" because they may be used for anything
-else, including parameters, texture generation information, or anything that
-can be stored inside a four-component vector.
TGSI_SEMANTIC_NORMAL
""""""""""""""""""""
-XXX no clue.
+Indicates that a vertex shader input is a normal vector. This is
+typically only used for legacy graphics APIs.
+
TGSI_SEMANTIC_FACE
""""""""""""""""""
-FACE is the facing bit, to store the facing information for the fragment
-shader. ``(f, 0, 0, 1)`` is the format. The first component will be positive
-when the fragment is front-facing, and negative when the component is
-back-facing.
+This label applies to fragment shader inputs only and indicates that
+the register contains front/back-face information of the form (F, 0,
+0, 1). The first component will be positive when the fragment belongs
+to a front-facing polygon, and negative when the fragment belongs to a
+back-facing polygon.
+
TGSI_SEMANTIC_EDGEFLAG
""""""""""""""""""""""
-XXX no clue
+For vertex shaders, this sematic label indicates that an input or
+output is a boolean edge flag. The register layout is [F, x, x, x]
+where F is 0.0 or 1.0 and x = don't care. Normally, the vertex shader
+simply copies the edge flag input to the edgeflag output.
+
+Edge flags are used to control which lines or points are actually
+drawn when the polygon mode converts triangles/quads/polygons into
+points or lines.
+
+TGSI_SEMANTIC_STENCIL
+""""""""""""""""""""""
+
+For fragment shaders, this semantic label indicates than an output
+is a writable stencil reference value. Only the Y component is writable.
+This allows the fragment shader to change the fragments stencilref value.
+
+
+Declaration Interpolate
+^^^^^^^^^^^^^^^^^^^^^^^
+
+This token is only valid for fragment shader INPUT declarations.
+
+The Interpolate field specifes the way input is being interpolated by
+the rasteriser and is one of TGSI_INTERPOLATE_*.
+
+The CylindricalWrap bitfield specifies which register components
+should be subject to cylindrical wrapping when interpolating by the
+rasteriser. If TGSI_CYLINDRICAL_WRAP_X is set to 1, the X component
+should be interpolated according to cylindrical wrapping rules.
+
+
+Declaration Sampler View
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+ Follows Declaration token if file is TGSI_FILE_SAMPLER_VIEW.
+
+ DCL SVIEW[#], resource, type(s)
+
+ Declares a shader input sampler view and assigns it to a SVIEW[#]
+ register.
+
+ resource can be one of BUFFER, 1D, 2D, 3D, 1DArray and 2DArray.
+
+ type must be 1 or 4 entries (if specifying on a per-component
+ level) out of UNORM, SNORM, SINT, UINT and FLOAT.
+
+
+Declaration Resource
+^^^^^^^^^^^^^^^^^^^^
+
+ Follows Declaration token if file is TGSI_FILE_RESOURCE.
+
+ DCL RES[#], resource [, RAW]
+
+ Declares a shader input resource and assigns it to a RES[#]
+ register.
+
+ resource can be one of BUFFER, 1D, 2D, 3D, CUBE, 1DArray and
+ 2DArray.
+
+ If the RAW keyword is not specified, the texture data will be
+ subject to conversion, swizzling and scaling as required to yield
+ the specified data type from the physical data format of the bound
+ resource.
+
+ If the RAW keyword is specified, no channel conversion will be
+ performed: the values read for each of the channels (X,Y,Z,W) will
+ correspond to consecutive words in the same order and format
+ they're found in memory. No element-to-address conversion will be
+ performed either: the value of the provided X coordinate will be
+ interpreted in byte units instead of texel units. The result of
+ accessing a misaligned address is undefined.
+
+
+Properties
+^^^^^^^^^^^^^^^^^^^^^^^^
+
+
+ Properties are general directives that apply to the whole TGSI program.
+
+FS_COORD_ORIGIN
+"""""""""""""""
+
+Specifies the fragment shader TGSI_SEMANTIC_POSITION coordinate origin.
+The default value is UPPER_LEFT.
+
+If UPPER_LEFT, the position will be (0,0) at the upper left corner and
+increase downward and rightward.
+If LOWER_LEFT, the position will be (0,0) at the lower left corner and
+increase upward and rightward.
+
+OpenGL defaults to LOWER_LEFT, and is configurable with the
+GL_ARB_fragment_coord_conventions extension.
+
+DirectX 9/10 use UPPER_LEFT.
+
+FS_COORD_PIXEL_CENTER
+"""""""""""""""""""""
+
+Specifies the fragment shader TGSI_SEMANTIC_POSITION pixel center convention.
+The default value is HALF_INTEGER.
+
+If HALF_INTEGER, the fractionary part of the position will be 0.5
+If INTEGER, the fractionary part of the position will be 0.0
+
+Note that this does not affect the set of fragments generated by
+rasterization, which is instead controlled by gl_rasterization_rules in the
+rasterizer.
+
+OpenGL defaults to HALF_INTEGER, and is configurable with the
+GL_ARB_fragment_coord_conventions extension.
+
+DirectX 9 uses INTEGER.
+DirectX 10 uses HALF_INTEGER.
+
+FS_COLOR0_WRITES_ALL_CBUFS
+""""""""""""""""""""""""""
+Specifies that writes to the fragment shader color 0 are replicated to all
+bound cbufs. This facilitates OpenGL's fragColor output vs fragData[0] where
+fragData is directed to a single color buffer, but fragColor is broadcast.
+
+VS_PROHIBIT_UCPS
+""""""""""""""""""""""""""
+If this property is set on the program bound to the shader stage before the
+fragment shader, user clip planes should have no effect (be disabled) even if
+that shader does not write to any clip distance outputs and the rasterizer's
+clip_plane_enable is non-zero.
+This property is only supported by drivers that also support shader clip
+distance outputs.
+This is useful for APIs that don't have UCPs and where clip distances written
+by a shader cannot be disabled.
+
+
+Texture Sampling and Texture Formats
+------------------------------------
+
+This table shows how texture image components are returned as (x,y,z,w) tuples
+by TGSI texture instructions, such as :opcode:`TEX`, :opcode:`TXD`, and
+:opcode:`TXP`. For reference, OpenGL and Direct3D conventions are shown as
+well.
+
++--------------------+--------------+--------------------+--------------+
+| Texture Components | Gallium | OpenGL | Direct3D 9 |
++====================+==============+====================+==============+
+| R | (r, 0, 0, 1) | (r, 0, 0, 1) | (r, 1, 1, 1) |
++--------------------+--------------+--------------------+--------------+
+| RG | (r, g, 0, 1) | (r, g, 0, 1) | (r, g, 1, 1) |
++--------------------+--------------+--------------------+--------------+
+| RGB | (r, g, b, 1) | (r, g, b, 1) | (r, g, b, 1) |
++--------------------+--------------+--------------------+--------------+
+| RGBA | (r, g, b, a) | (r, g, b, a) | (r, g, b, a) |
++--------------------+--------------+--------------------+--------------+
+| A | (0, 0, 0, a) | (0, 0, 0, a) | (0, 0, 0, a) |
++--------------------+--------------+--------------------+--------------+
+| L | (l, l, l, 1) | (l, l, l, 1) | (l, l, l, 1) |
++--------------------+--------------+--------------------+--------------+
+| LA | (l, l, l, a) | (l, l, l, a) | (l, l, l, a) |
++--------------------+--------------+--------------------+--------------+
+| I | (i, i, i, i) | (i, i, i, i) | N/A |
++--------------------+--------------+--------------------+--------------+
+| UV | XXX TBD | (0, 0, 0, 1) | (u, v, 1, 1) |
+| | | [#envmap-bumpmap]_ | |
++--------------------+--------------+--------------------+--------------+
+| Z | XXX TBD | (z, z, z, 1) | (0, z, 0, 1) |
+| | | [#depth-tex-mode]_ | |
++--------------------+--------------+--------------------+--------------+
+| S | (s, s, s, s) | unknown | unknown |
++--------------------+--------------+--------------------+--------------+
+
+.. [#envmap-bumpmap] http://www.opengl.org/registry/specs/ATI/envmap_bumpmap.txt
+.. [#depth-tex-mode] the default is (z, z, z, 1) but may also be (0, 0, 0, z)
+ or (z, z, z, z) depending on the value of GL_DEPTH_TEXTURE_MODE.
projects / mesa.git / blobdiff