2 * Copyright © 2015 Red Hat
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5 * copy of this software and associated documentation files (the "Software"),
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9 * Software is furnished to do so, subject to the following conditions:
11 * The above copyright notice and this permission notice (including the next
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15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
25 #include "nir_builder.h"
26 #include "program/prog_instruction.h"
28 /* Lower gl_FragCoord (and fddy) to account for driver's requested coordinate-
29 * origin and pixel-center vs. shader. If transformation is required, a
30 * gl_FbWposYTransform uniform is inserted (with the specified state-slots)
31 * and additional instructions are inserted to transform gl_FragCoord (and
34 * This is based on the logic in emit_wpos()/emit_wpos_adjustment() in TGSI
37 * Run before nir_lower_io.
41 const nir_lower_wpos_ytransform_options
*options
;
44 nir_variable
*transform
;
45 } lower_wpos_ytransform_state
;
48 get_transform(lower_wpos_ytransform_state
*state
)
50 if (state
->transform
== NULL
) {
51 /* NOTE: name must be prefixed w/ "gl_" to trigger slot based
52 * special handling in uniform setup:
54 nir_variable
*var
= nir_variable_create(state
->shader
,
57 "gl_FbWposYTransform");
59 var
->num_state_slots
= 1;
60 var
->state_slots
= ralloc_array(var
, nir_state_slot
, 1);
61 var
->state_slots
[0].swizzle
= SWIZZLE_XYZW
;
62 memcpy(var
->state_slots
[0].tokens
, state
->options
->state_tokens
,
63 sizeof(var
->state_slots
[0].tokens
));
65 state
->transform
= var
;
67 return nir_load_var(&state
->b
, state
->transform
);
70 /* NIR equiv of TGSI CMP instruction: */
72 nir_cmp(nir_builder
*b
, nir_ssa_def
*src0
, nir_ssa_def
*src1
, nir_ssa_def
*src2
)
74 return nir_bcsel(b
, nir_flt(b
, src0
, nir_imm_float(b
, 0.0)), src1
, src2
);
77 /* see emit_wpos_adjustment() in st_mesa_to_tgsi.c */
79 emit_wpos_adjustment(lower_wpos_ytransform_state
*state
,
80 nir_intrinsic_instr
*intr
,
81 bool invert
, float adjX
, float adjY
[2])
83 nir_builder
*b
= &state
->b
;
84 nir_variable
*fragcoord
= intr
->variables
[0]->var
;
85 nir_ssa_def
*wpostrans
, *wpos_temp
, *wpos_temp_y
, *wpos_input
;
87 assert(intr
->dest
.is_ssa
);
89 b
->cursor
= nir_before_instr(&intr
->instr
);
91 wpostrans
= get_transform(state
);
92 wpos_input
= nir_load_var(b
, fragcoord
);
94 /* First, apply the coordinate shift: */
95 if (adjX
|| adjY
[0] || adjY
[1]) {
96 if (adjY
[0] != adjY
[1]) {
97 /* Adjust the y coordinate by adjY[1] or adjY[0] respectively
98 * depending on whether inversion is actually going to be applied
99 * or not, which is determined by testing against the inversion
100 * state variable used below, which will be either +1 or -1.
102 nir_ssa_def
*adj_temp
;
104 adj_temp
= nir_cmp(b
,
105 nir_channel(b
, wpostrans
, invert
? 2 : 0),
106 nir_imm_vec4(b
, adjX
, adjY
[0], 0.0f
, 0.0f
),
107 nir_imm_vec4(b
, adjX
, adjY
[1], 0.0f
, 0.0f
));
109 wpos_temp
= nir_fadd(b
, wpos_input
, adj_temp
);
111 wpos_temp
= nir_fadd(b
,
113 nir_imm_vec4(b
, adjX
, adjY
[0], 0.0f
, 0.0f
));
115 wpos_input
= wpos_temp
;
117 /* MOV wpos_temp, input[wpos]
119 wpos_temp
= wpos_input
;
122 /* Now the conditional y flip: STATE_FB_WPOS_Y_TRANSFORM.xy/zw will be
123 * inversion/identity, or the other way around if we're drawing to an FBO.
126 /* wpos_temp.y = wpos_input * wpostrans.xxxx + wpostrans.yyyy */
127 wpos_temp_y
= nir_fadd(b
, nir_fmul(b
, nir_channel(b
, wpos_temp
, 1),
128 nir_channel(b
, wpostrans
, 0)),
129 nir_channel(b
, wpostrans
, 1));
131 /* wpos_temp.y = wpos_input * wpostrans.zzzz + wpostrans.wwww */
132 wpos_temp_y
= nir_fadd(b
, nir_fmul(b
, nir_channel(b
, wpos_temp
, 1),
133 nir_channel(b
, wpostrans
, 2)),
134 nir_channel(b
, wpostrans
, 3));
137 wpos_temp
= nir_vec4(b
,
138 nir_channel(b
, wpos_temp
, 0),
140 nir_channel(b
, wpos_temp
, 2),
141 nir_channel(b
, wpos_temp
, 3));
143 nir_ssa_def_rewrite_uses(&intr
->dest
.ssa
, nir_src_for_ssa(wpos_temp
));
147 lower_fragcoord(lower_wpos_ytransform_state
*state
, nir_intrinsic_instr
*intr
)
149 const nir_lower_wpos_ytransform_options
*options
= state
->options
;
150 nir_variable
*fragcoord
= intr
->variables
[0]->var
;
152 float adjY
[2] = { 0.0f
, 0.0f
};
155 /* Based on logic in emit_wpos():
157 * Query the pixel center conventions supported by the pipe driver and set
158 * adjX, adjY to help out if it cannot handle the requested one internally.
160 * The bias of the y-coordinate depends on whether y-inversion takes place
161 * (adjY[1]) or not (adjY[0]), which is in turn dependent on whether we are
162 * drawing to an FBO (causes additional inversion), and whether the pipe
163 * driver origin and the requested origin differ (the latter condition is
164 * stored in the 'invert' variable).
166 * For height = 100 (i = integer, h = half-integer, l = lower, u = upper):
173 * l,i -> u,i: ( 0.0 + 1.0) * -1 + 100 = 99
174 * l,h -> u,h: ( 0.5 + 0.0) * -1 + 100 = 99.5
175 * u,i -> l,i: (99.0 + 1.0) * -1 + 100 = 0
176 * u,h -> l,h: (99.5 + 0.0) * -1 + 100 = 0.5
178 * inversion and center shift:
179 * l,i -> u,h: ( 0.0 + 0.5) * -1 + 100 = 99.5
180 * l,h -> u,i: ( 0.5 + 0.5) * -1 + 100 = 99
181 * u,i -> l,h: (99.0 + 0.5) * -1 + 100 = 0.5
182 * u,h -> l,i: (99.5 + 0.5) * -1 + 100 = 0
185 if (fragcoord
->data
.origin_upper_left
) {
186 /* Fragment shader wants origin in upper-left */
187 if (options
->fs_coord_origin_upper_left
) {
188 /* the driver supports upper-left origin */
189 } else if (options
->fs_coord_origin_lower_left
) {
190 /* the driver supports lower-left origin, need to invert Y */
193 unreachable("invalid options");
196 /* Fragment shader wants origin in lower-left */
197 if (options
->fs_coord_origin_lower_left
) {
198 /* the driver supports lower-left origin */
199 } else if (options
->fs_coord_origin_upper_left
) {
200 /* the driver supports upper-left origin, need to invert Y */
203 unreachable("invalid options");
207 if (fragcoord
->data
.pixel_center_integer
) {
208 /* Fragment shader wants pixel center integer */
209 if (options
->fs_coord_pixel_center_integer
) {
210 /* the driver supports pixel center integer */
212 } else if (options
->fs_coord_pixel_center_half_integer
) {
213 /* the driver supports pixel center half integer, need to bias X,Y */
218 unreachable("invalid options");
221 /* Fragment shader wants pixel center half integer */
222 if (options
->fs_coord_pixel_center_half_integer
) {
223 /* the driver supports pixel center half integer */
224 } else if (options
->fs_coord_pixel_center_integer
) {
225 /* the driver supports pixel center integer, need to bias X,Y */
226 adjX
= adjY
[0] = adjY
[1] = 0.5f
;
228 unreachable("invalid options");
232 emit_wpos_adjustment(state
, intr
, invert
, adjX
, adjY
);
235 /* turns 'fddy(p)' into 'fddy(fmul(p, transform.x))' */
237 lower_fddy(lower_wpos_ytransform_state
*state
, nir_alu_instr
*fddy
)
239 nir_builder
*b
= &state
->b
;
240 nir_ssa_def
*p
, *pt
, *trans
;
242 b
->cursor
= nir_before_instr(&fddy
->instr
);
244 p
= nir_ssa_for_alu_src(b
, fddy
, 0);
245 trans
= get_transform(state
);
246 pt
= nir_fmul(b
, p
, nir_channel(b
, trans
, 0));
248 nir_instr_rewrite_src(&fddy
->instr
,
250 nir_src_for_ssa(pt
));
252 for (unsigned i
= 0; i
< 4; i
++)
253 fddy
->src
[0].swizzle
[i
] = MIN2(i
, pt
->num_components
- 1);
256 /* Multiply interp_var_at_offset's offset by transform.x to flip it. */
258 lower_interp_var_at_offset(lower_wpos_ytransform_state
*state
,
259 nir_intrinsic_instr
*interp
)
261 nir_builder
*b
= &state
->b
;
265 b
->cursor
= nir_before_instr(&interp
->instr
);
267 offset
= nir_ssa_for_src(b
, interp
->src
[0], 2);
268 flip_y
= nir_fmul(b
, nir_channel(b
, offset
, 1),
269 nir_channel(b
, get_transform(state
), 0));
270 nir_instr_rewrite_src(&interp
->instr
, &interp
->src
[0],
271 nir_src_for_ssa(nir_vec2(b
, nir_channel(b
, offset
, 0),
276 lower_load_sample_pos(lower_wpos_ytransform_state
*state
,
277 nir_intrinsic_instr
*intr
)
279 nir_builder
*b
= &state
->b
;
280 b
->cursor
= nir_after_instr(&intr
->instr
);
282 nir_ssa_def
*pos
= &intr
->dest
.ssa
;
283 nir_ssa_def
*scale
= nir_channel(b
, get_transform(state
), 0);
284 nir_ssa_def
*neg_scale
= nir_channel(b
, get_transform(state
), 2);
285 /* Either y or 1-y for scale equal to 1 or -1 respectively. */
286 nir_ssa_def
*flipped_y
=
287 nir_fadd(b
, nir_fmax(b
, neg_scale
, nir_imm_float(b
, 0.0)),
288 nir_fmul(b
, nir_channel(b
, pos
, 1), scale
));
289 nir_ssa_def
*flipped_pos
= nir_vec2(b
, nir_channel(b
, pos
, 0), flipped_y
);
291 nir_ssa_def_rewrite_uses_after(&intr
->dest
.ssa
, nir_src_for_ssa(flipped_pos
),
292 flipped_pos
->parent_instr
);
296 lower_wpos_ytransform_block(lower_wpos_ytransform_state
*state
, nir_block
*block
)
298 nir_foreach_instr_safe(instr
, block
) {
299 if (instr
->type
== nir_instr_type_intrinsic
) {
300 nir_intrinsic_instr
*intr
= nir_instr_as_intrinsic(instr
);
301 if (intr
->intrinsic
== nir_intrinsic_load_var
) {
302 nir_deref_var
*dvar
= intr
->variables
[0];
303 nir_variable
*var
= dvar
->var
;
305 if ((var
->data
.mode
== nir_var_shader_in
&&
306 var
->data
.location
== VARYING_SLOT_POS
) ||
307 (var
->data
.mode
== nir_var_system_value
&&
308 var
->data
.location
== SYSTEM_VALUE_FRAG_COORD
)) {
309 /* gl_FragCoord should not have array/struct derefs: */
310 assert(dvar
->deref
.child
== NULL
);
311 lower_fragcoord(state
, intr
);
312 } else if (var
->data
.mode
== nir_var_system_value
&&
313 var
->data
.location
== SYSTEM_VALUE_SAMPLE_POS
) {
314 assert(dvar
->deref
.child
== NULL
);
315 lower_load_sample_pos(state
, intr
);
317 } else if (intr
->intrinsic
== nir_intrinsic_load_frag_coord
) {
318 lower_fragcoord(state
, intr
);
319 } else if (intr
->intrinsic
== nir_intrinsic_load_sample_pos
) {
320 lower_load_sample_pos(state
, intr
);
321 } else if (intr
->intrinsic
== nir_intrinsic_interp_var_at_offset
) {
322 lower_interp_var_at_offset(state
, intr
);
324 } else if (instr
->type
== nir_instr_type_alu
) {
325 nir_alu_instr
*alu
= nir_instr_as_alu(instr
);
326 if (alu
->op
== nir_op_fddy
||
327 alu
->op
== nir_op_fddy_fine
||
328 alu
->op
== nir_op_fddy_coarse
)
329 lower_fddy(state
, alu
);
335 lower_wpos_ytransform_impl(lower_wpos_ytransform_state
*state
, nir_function_impl
*impl
)
337 nir_builder_init(&state
->b
, impl
);
339 nir_foreach_block(block
, impl
) {
340 lower_wpos_ytransform_block(state
, block
);
342 nir_metadata_preserve(impl
, nir_metadata_block_index
|
343 nir_metadata_dominance
);
347 nir_lower_wpos_ytransform(nir_shader
*shader
,
348 const nir_lower_wpos_ytransform_options
*options
)
350 lower_wpos_ytransform_state state
= {
355 nir_assert_lowered_derefs(shader
, nir_lower_load_store_derefs
);
357 assert(shader
->info
.stage
== MESA_SHADER_FRAGMENT
);
359 nir_foreach_function(function
, shader
) {
361 lower_wpos_ytransform_impl(&state
, function
->impl
);
364 return state
.transform
!= NULL
;