/*
* Copyright © 2015 Red Hat
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "nir.h"
#include "nir_builder.h"
#include "program/prog_instruction.h"
/* Lower gl_FragCoord (and fddy) to account for driver's requested coordinate-
* origin and pixel-center vs. shader. If transformation is required, a
* gl_FbWposYTransform uniform is inserted (with the specified state-slots)
* and additional instructions are inserted to transform gl_FragCoord (and
* fddy src arg).
*
* This is based on the logic in emit_wpos()/emit_wpos_adjustment() in TGSI
* compiler.
*
* Run before nir_lower_io.
*/
typedef struct {
const nir_lower_wpos_ytransform_options *options;
nir_shader *shader;
nir_builder b;
nir_variable *transform;
} lower_wpos_ytransform_state;
static nir_ssa_def *
get_transform(lower_wpos_ytransform_state *state)
{
if (state->transform == NULL) {
/* NOTE: name must be prefixed w/ "gl_" to trigger slot based
* special handling in uniform setup:
*/
nir_variable *var = nir_variable_create(state->shader,
nir_var_uniform,
glsl_vec4_type(),
"gl_FbWposYTransform");
var->num_state_slots = 1;
var->state_slots = ralloc_array(var, nir_state_slot, 1);
var->state_slots[0].swizzle = SWIZZLE_XYZW;
memcpy(var->state_slots[0].tokens, state->options->state_tokens,
sizeof(var->state_slots[0].tokens));
state->transform = var;
}
return nir_load_var(&state->b, state->transform);
}
/* NIR equiv of TGSI CMP instruction: */
static nir_ssa_def *
nir_cmp(nir_builder *b, nir_ssa_def *src0, nir_ssa_def *src1, nir_ssa_def *src2)
{
return nir_bcsel(b, nir_flt(b, src0, nir_imm_float(b, 0.0)), src1, src2);
}
/* see emit_wpos_adjustment() in st_mesa_to_tgsi.c */
static void
emit_wpos_adjustment(lower_wpos_ytransform_state *state,
nir_intrinsic_instr *intr,
bool invert, float adjX, float adjY[2])
{
nir_builder *b = &state->b;
nir_variable *fragcoord = intr->variables[0]->var;
nir_ssa_def *wpostrans, *wpos_temp, *wpos_temp_y, *wpos_input;
assert(intr->dest.is_ssa);
b->cursor = nir_before_instr(&intr->instr);
wpostrans = get_transform(state);
wpos_input = nir_load_var(b, fragcoord);
/* First, apply the coordinate shift: */
if (adjX || adjY[0] || adjY[1]) {
if (adjY[0] != adjY[1]) {
/* Adjust the y coordinate by adjY[1] or adjY[0] respectively
* depending on whether inversion is actually going to be applied
* or not, which is determined by testing against the inversion
* state variable used below, which will be either +1 or -1.
*/
nir_ssa_def *adj_temp;
adj_temp = nir_cmp(b,
nir_channel(b, wpostrans, invert ? 2 : 0),
nir_imm_vec4(b, adjX, adjY[0], 0.0f, 0.0f),
nir_imm_vec4(b, adjX, adjY[1], 0.0f, 0.0f));
wpos_temp = nir_fadd(b, wpos_input, adj_temp);
} else {
wpos_temp = nir_fadd(b,
wpos_input,
nir_imm_vec4(b, adjX, adjY[0], 0.0f, 0.0f));
}
wpos_input = wpos_temp;
} else {
/* MOV wpos_temp, input[wpos]
*/
wpos_temp = wpos_input;
}
/* Now the conditional y flip: STATE_FB_WPOS_Y_TRANSFORM.xy/zw will be
* inversion/identity, or the other way around if we're drawing to an FBO.
*/
if (invert) {
/* wpos_temp.y = wpos_input * wpostrans.xxxx + wpostrans.yyyy */
wpos_temp_y = nir_fadd(b, nir_fmul(b, nir_channel(b, wpos_temp, 1),
nir_channel(b, wpostrans, 0)),
nir_channel(b, wpostrans, 1));
} else {
/* wpos_temp.y = wpos_input * wpostrans.zzzz + wpostrans.wwww */
wpos_temp_y = nir_fadd(b, nir_fmul(b, nir_channel(b, wpos_temp, 1),
nir_channel(b, wpostrans, 2)),
nir_channel(b, wpostrans, 3));
}
wpos_temp = nir_vec4(b,
nir_channel(b, wpos_temp, 0),
wpos_temp_y,
nir_channel(b, wpos_temp, 2),
nir_channel(b, wpos_temp, 3));
nir_ssa_def_rewrite_uses(&intr->dest.ssa, nir_src_for_ssa(wpos_temp));
}
static void
lower_fragcoord(lower_wpos_ytransform_state *state, nir_intrinsic_instr *intr)
{
const nir_lower_wpos_ytransform_options *options = state->options;
nir_variable *fragcoord = intr->variables[0]->var;
float adjX = 0.0f;
float adjY[2] = { 0.0f, 0.0f };
bool invert = false;
/* Based on logic in emit_wpos():
*
* Query the pixel center conventions supported by the pipe driver and set
* adjX, adjY to help out if it cannot handle the requested one internally.
*
* The bias of the y-coordinate depends on whether y-inversion takes place
* (adjY[1]) or not (adjY[0]), which is in turn dependent on whether we are
* drawing to an FBO (causes additional inversion), and whether the pipe
* driver origin and the requested origin differ (the latter condition is
* stored in the 'invert' variable).
*
* For height = 100 (i = integer, h = half-integer, l = lower, u = upper):
*
* center shift only:
* i -> h: +0.5
* h -> i: -0.5
*
* inversion only:
* l,i -> u,i: ( 0.0 + 1.0) * -1 + 100 = 99
* l,h -> u,h: ( 0.5 + 0.0) * -1 + 100 = 99.5
* u,i -> l,i: (99.0 + 1.0) * -1 + 100 = 0
* u,h -> l,h: (99.5 + 0.0) * -1 + 100 = 0.5
*
* inversion and center shift:
* l,i -> u,h: ( 0.0 + 0.5) * -1 + 100 = 99.5
* l,h -> u,i: ( 0.5 + 0.5) * -1 + 100 = 99
* u,i -> l,h: (99.0 + 0.5) * -1 + 100 = 0.5
* u,h -> l,i: (99.5 + 0.5) * -1 + 100 = 0
*/
if (fragcoord->data.origin_upper_left) {
/* Fragment shader wants origin in upper-left */
if (options->fs_coord_origin_upper_left) {
/* the driver supports upper-left origin */
} else if (options->fs_coord_origin_lower_left) {
/* the driver supports lower-left origin, need to invert Y */
invert = true;
} else {
unreachable("invalid options");
}
} else {
/* Fragment shader wants origin in lower-left */
if (options->fs_coord_origin_lower_left) {
/* the driver supports lower-left origin */
} else if (options->fs_coord_origin_upper_left) {
/* the driver supports upper-left origin, need to invert Y */
invert = true;
} else {
unreachable("invalid options");
}
}
if (fragcoord->data.pixel_center_integer) {
/* Fragment shader wants pixel center integer */
if (options->fs_coord_pixel_center_integer) {
/* the driver supports pixel center integer */
adjY[1] = 1.0f;
} else if (options->fs_coord_pixel_center_half_integer) {
/* the driver supports pixel center half integer, need to bias X,Y */
adjX = -0.5f;
adjY[0] = -0.5f;
adjY[1] = 0.5f;
} else {
unreachable("invalid options");
}
} else {
/* Fragment shader wants pixel center half integer */
if (options->fs_coord_pixel_center_half_integer) {
/* the driver supports pixel center half integer */
} else if (options->fs_coord_pixel_center_integer) {
/* the driver supports pixel center integer, need to bias X,Y */
adjX = adjY[0] = adjY[1] = 0.5f;
} else {
unreachable("invalid options");
}
}
emit_wpos_adjustment(state, intr, invert, adjX, adjY);
}
/* turns 'fddy(p)' into 'fddy(fmul(p, transform.x))' */
static void
lower_fddy(lower_wpos_ytransform_state *state, nir_alu_instr *fddy)
{
nir_builder *b = &state->b;
nir_ssa_def *p, *pt, *trans;
b->cursor = nir_before_instr(&fddy->instr);
p = nir_ssa_for_alu_src(b, fddy, 0);
trans = get_transform(state);
pt = nir_fmul(b, p, nir_channel(b, trans, 0));
nir_instr_rewrite_src(&fddy->instr,
&fddy->src[0].src,
nir_src_for_ssa(pt));
for (unsigned i = 0; i < 4; i++)
fddy->src[0].swizzle[i] = MIN2(i, pt->num_components - 1);
}
/* Multiply interp_var_at_offset's offset by transform.x to flip it. */
static void
lower_interp_var_at_offset(lower_wpos_ytransform_state *state,
nir_intrinsic_instr *interp)
{
nir_builder *b = &state->b;
nir_ssa_def *offset;
nir_ssa_def *flip_y;
b->cursor = nir_before_instr(&interp->instr);
offset = nir_ssa_for_src(b, interp->src[0], 2);
flip_y = nir_fmul(b, nir_channel(b, offset, 1),
nir_channel(b, get_transform(state), 0));
nir_instr_rewrite_src(&interp->instr, &interp->src[0],
nir_src_for_ssa(nir_vec2(b, nir_channel(b, offset, 0),
flip_y)));
}
static void
lower_load_sample_pos(lower_wpos_ytransform_state *state,
nir_intrinsic_instr *intr)
{
nir_builder *b = &state->b;
b->cursor = nir_after_instr(&intr->instr);
nir_ssa_def *pos = &intr->dest.ssa;
nir_ssa_def *scale = nir_channel(b, get_transform(state), 0);
nir_ssa_def *neg_scale = nir_channel(b, get_transform(state), 2);
/* Either y or 1-y for scale equal to 1 or -1 respectively. */
nir_ssa_def *flipped_y =
nir_fadd(b, nir_fmax(b, neg_scale, nir_imm_float(b, 0.0)),
nir_fmul(b, nir_channel(b, pos, 1), scale));
nir_ssa_def *flipped_pos = nir_vec2(b, nir_channel(b, pos, 0), flipped_y);
nir_ssa_def_rewrite_uses_after(&intr->dest.ssa, nir_src_for_ssa(flipped_pos),
flipped_pos->parent_instr);
}
static void
lower_wpos_ytransform_block(lower_wpos_ytransform_state *state, nir_block *block)
{
nir_foreach_instr_safe(instr, block) {
if (instr->type == nir_instr_type_intrinsic) {
nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
if (intr->intrinsic == nir_intrinsic_load_var) {
nir_deref_var *dvar = intr->variables[0];
nir_variable *var = dvar->var;
if ((var->data.mode == nir_var_shader_in &&
var->data.location == VARYING_SLOT_POS) ||
(var->data.mode == nir_var_system_value &&
var->data.location == SYSTEM_VALUE_FRAG_COORD)) {
/* gl_FragCoord should not have array/struct derefs: */
assert(dvar->deref.child == NULL);
lower_fragcoord(state, intr);
} else if (var->data.mode == nir_var_system_value &&
var->data.location == SYSTEM_VALUE_SAMPLE_POS) {
assert(dvar->deref.child == NULL);
lower_load_sample_pos(state, intr);
}
} else if (intr->intrinsic == nir_intrinsic_load_frag_coord) {
lower_fragcoord(state, intr);
} else if (intr->intrinsic == nir_intrinsic_load_sample_pos) {
lower_load_sample_pos(state, intr);
} else if (intr->intrinsic == nir_intrinsic_interp_var_at_offset) {
lower_interp_var_at_offset(state, intr);
}
} else if (instr->type == nir_instr_type_alu) {
nir_alu_instr *alu = nir_instr_as_alu(instr);
if (alu->op == nir_op_fddy ||
alu->op == nir_op_fddy_fine ||
alu->op == nir_op_fddy_coarse)
lower_fddy(state, alu);
}
}
}
static void
lower_wpos_ytransform_impl(lower_wpos_ytransform_state *state, nir_function_impl *impl)
{
nir_builder_init(&state->b, impl);
nir_foreach_block(block, impl) {
lower_wpos_ytransform_block(state, block);
}
nir_metadata_preserve(impl, nir_metadata_block_index |
nir_metadata_dominance);
}
bool
nir_lower_wpos_ytransform(nir_shader *shader,
const nir_lower_wpos_ytransform_options *options)
{
lower_wpos_ytransform_state state = {
.options = options,
.shader = shader,
};
assert(shader->info.stage == MESA_SHADER_FRAGMENT);
nir_foreach_function(function, shader) {
if (function->impl)
lower_wpos_ytransform_impl(&state, function->impl);
}
return state.transform != NULL;
}