mirror of https://gitlab.freedesktop.org/mesa/mesa
86 lines
3.1 KiB
C
86 lines
3.1 KiB
C
/*
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* Copyright © 2015 Red Hat
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* Copyright © 2016 Intel Corporation
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#include "nir.h"
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#include "nir_builder.h"
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/**
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* This pass adds <0.5, 0.5> to all uses of gl_FragCoord.
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*
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* Run before nir_lower_io().
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*
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* For a more full featured pass, consider using nir_lower_wpos_ytransform(),
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* which can handle pixel center integer / half integer, and origin lower
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* left / upper left transformations.
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*
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* This simple pass is primarily intended for use by Vulkan drivers on
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* hardware which provides an integer pixel center. Vulkan mandates that
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* the pixel center must be half-integer, and also that the coordinate
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* system's origin must be upper left. This means that there's no need
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* for a uniform - we can always just add a constant. In the case that
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* sample shading is enabled, Vulkan expects FragCoord to include sample
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* positions.
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*/
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static void
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update_fragcoord(nir_builder *b, nir_intrinsic_instr *intr)
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{
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nir_def *wpos = &intr->def;
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b->cursor = nir_after_instr(&intr->instr);
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nir_def *spos = nir_load_sample_pos_or_center(b);
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wpos = nir_fadd(b, wpos,
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nir_vec4(b,
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nir_channel(b, spos, 0),
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nir_channel(b, spos, 1),
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nir_imm_float(b, 0.0f),
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nir_imm_float(b, 0.0f)));
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nir_def_rewrite_uses_after(&intr->def, wpos,
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wpos->parent_instr);
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}
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static bool
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lower_wpos_center_instr(nir_builder *b, nir_intrinsic_instr *intr, void *data)
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{
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if (intr->intrinsic != nir_intrinsic_load_frag_coord)
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return false;
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update_fragcoord(b, intr);
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return true;
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}
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bool
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nir_lower_wpos_center(nir_shader *shader)
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{
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assert(shader->info.stage == MESA_SHADER_FRAGMENT);
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return nir_shader_intrinsics_pass(shader, lower_wpos_center_instr,
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nir_metadata_block_index |
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nir_metadata_dominance,
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NULL);
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}
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