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tgsi: add new tgsi_two_side.c utility code

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This could be used by any driver where the device doesn't directly
support two-sided lighting.  This code modifies a fragment shader
to accecpt back-face colors and choose between the front/back colors
depending on the triangle's front-face sign.
This commit is contained in:
Brian Paul
2015-09-01 16:29:17 -06:00
parent da33c2434b
commit a65bdf5f47
3 changed files with 264 additions and 0 deletions
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src/gallium/auxiliary/Makefile.sources
+2
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@@ -154,6 +154,8 @@ C_SOURCES := \
tgsi/tgsi_text.h \
tgsi/tgsi_transform.c \
tgsi/tgsi_transform.h \
tgsi/tgsi_two_side.c \
tgsi/tgsi_two_side.h \
tgsi/tgsi_ureg.c \
tgsi/tgsi_ureg.h \
tgsi/tgsi_util.c \
src/gallium/auxiliary/tgsi/tgsi_two_side.c
+228
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@@ -0,0 +1,228 @@
/*
* Copyright 2013 VMware, Inc.
* All Rights Reserved.
*
* 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, sub license, 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 NON-INFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS AND/OR ITS SUPPLIERS 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.
*/
/**
* This utility transforms fragment shaders to facilitate two-sided lighting.
*
* Basically, if the FS has any color inputs (TGSI_SEMANTIC_COLOR) we'll:
* 1. create corresponding back-color inputs (TGSI_SEMANTIC_BCOLOR)
* 2. use the FACE register to choose between front/back colors and put the
* selected color in new temp regs.
* 3. replace reads of the original color inputs with the new temp regs.
*
* Then, the driver just needs to link the VS front/back output colors to
* the FS front/back input colors.
*/
#include "util/u_debug.h"
#include "util/u_math.h"
#include "tgsi_info.h"
#include "tgsi_two_side.h"
#include "tgsi_transform.h"
#define INVALID_INDEX 9999
struct two_side_transform_context
{
struct tgsi_transform_context base;
uint num_temps;
uint num_inputs;
uint face_input; /**< index of the FACE input */
uint front_color_input[2]; /**< INPUT regs */
uint front_color_interp[2];/**< TGSI_INTERPOLATE_x */
uint back_color_input[2]; /**< INPUT regs */
uint new_colors[2]; /**< TEMP regs */
};
static inline struct two_side_transform_context *
two_side_transform_context(struct tgsi_transform_context *ctx)
{
return (struct two_side_transform_context *) ctx;
}
static void
xform_decl(struct tgsi_transform_context *ctx,
struct tgsi_full_declaration *decl)
{
struct two_side_transform_context *ts = two_side_transform_context(ctx);
if (decl->Declaration.File == TGSI_FILE_INPUT) {
if (decl->Semantic.Name == TGSI_SEMANTIC_COLOR) {
/* found a front color */
assert(decl->Semantic.Index < 2);
ts->front_color_input[decl->Semantic.Index] = decl->Range.First;
ts->front_color_interp[decl->Semantic.Index] = decl->Interp.Interpolate;
}
else if (decl->Semantic.Name == TGSI_SEMANTIC_FACE) {
ts->face_input = decl->Range.First;
}
ts->num_inputs = MAX2(ts->num_inputs, decl->Range.Last + 1);
}
else if (decl->Declaration.File == TGSI_FILE_TEMPORARY) {
ts->num_temps = MAX2(ts->num_temps, decl->Range.Last + 1);
}
ctx->emit_declaration(ctx, decl);
}
static void
emit_prolog(struct tgsi_transform_context *ctx)
{
struct two_side_transform_context *ts = two_side_transform_context(ctx);
struct tgsi_full_declaration decl;
struct tgsi_full_instruction inst;
uint num_colors = 0;
uint i;
/* Declare 0, 1 or 2 new BCOLOR inputs */
for (i = 0; i < 2; i++) {
if (ts->front_color_input[i] != INVALID_INDEX) {
decl = tgsi_default_full_declaration();
decl.Declaration.File = TGSI_FILE_INPUT;
decl.Declaration.Interpolate = 1;
decl.Declaration.Semantic = 1;
decl.Semantic.Name = TGSI_SEMANTIC_BCOLOR;
decl.Semantic.Index = i;
decl.Range.First = decl.Range.Last = ts->num_inputs++;
decl.Interp.Interpolate = ts->front_color_interp[i];
ctx->emit_declaration(ctx, &decl);
ts->back_color_input[i] = decl.Range.First;
num_colors++;
}
}
if (num_colors > 0) {
/* Declare 1 or 2 temp registers */
decl = tgsi_default_full_declaration();
decl.Declaration.File = TGSI_FILE_TEMPORARY;
decl.Range.First = ts->num_temps;
decl.Range.Last = ts->num_temps + num_colors - 1;
ctx->emit_declaration(ctx, &decl);
ts->new_colors[0] = ts->num_temps;
ts->new_colors[1] = ts->num_temps + 1;
if (ts->face_input == INVALID_INDEX) {
/* declare FACE INPUT register */
decl = tgsi_default_full_declaration();
decl.Declaration.File = TGSI_FILE_INPUT;
decl.Declaration.Semantic = 1;
decl.Semantic.Name = TGSI_SEMANTIC_FACE;
decl.Semantic.Index = 0;
decl.Range.First = decl.Range.Last = ts->num_inputs++;
ctx->emit_declaration(ctx, &decl);
ts->face_input = decl.Range.First;
}
/* CMP temp[c0], face, bcolor[c0], fcolor[c0]
* temp[c0] = face < 0.0 ? bcolor[c0] : fcolor[c0]
*/
for (i = 0; i < 2; i++) {
if (ts->front_color_input[i] != INVALID_INDEX) {
inst = tgsi_default_full_instruction();
inst.Instruction.Opcode = TGSI_OPCODE_CMP;
inst.Instruction.NumDstRegs = 1;
inst.Dst[0].Register.File = TGSI_FILE_TEMPORARY;
inst.Dst[0].Register.Index = ts->new_colors[i];
inst.Instruction.NumSrcRegs = 3;
inst.Src[0].Register.File = TGSI_FILE_INPUT;
inst.Src[0].Register.Index = ts->face_input;
inst.Src[1].Register.File = TGSI_FILE_INPUT;
inst.Src[1].Register.Index = ts->back_color_input[i];
inst.Src[2].Register.File = TGSI_FILE_INPUT;
inst.Src[2].Register.Index = ts->front_color_input[i];
ctx->emit_instruction(ctx, &inst);
}
}
}
}
static void
xform_inst(struct tgsi_transform_context *ctx,
struct tgsi_full_instruction *inst)
{
struct two_side_transform_context *ts = two_side_transform_context(ctx);
const struct tgsi_opcode_info *info =
tgsi_get_opcode_info(inst->Instruction.Opcode);
uint i, j;
/* Look for src regs which reference the input color and replace
* them with the temp color.
*/
for (i = 0; i < info->num_src; i++) {
if (inst->Src[i].Register.File == TGSI_FILE_INPUT) {
for (j = 0; j < 2; j++) {
if (inst->Src[i].Register.Index == ts->front_color_input[j]) {
/* replace color input with temp reg */
inst->Src[i].Register.File = TGSI_FILE_TEMPORARY;
inst->Src[i].Register.Index = ts->new_colors[j];
break;
}
}
}
}
ctx->emit_instruction(ctx, inst);
}
struct tgsi_token *
tgsi_add_two_side(const struct tgsi_token *tokens_in)
{
struct two_side_transform_context transform;
const uint num_new_tokens = 100; /* should be enough */
const uint new_len = tgsi_num_tokens(tokens_in) + num_new_tokens;
struct tgsi_token *new_tokens;
/* setup transformation context */
memset(&transform, 0, sizeof(transform));
transform.base.transform_declaration = xform_decl;
transform.base.transform_instruction = xform_inst;
transform.base.prolog = emit_prolog;
transform.face_input = INVALID_INDEX;
transform.front_color_input[0] = INVALID_INDEX;
transform.front_color_input[1] = INVALID_INDEX;
transform.front_color_interp[0] = TGSI_INTERPOLATE_COLOR;
transform.front_color_interp[1] = TGSI_INTERPOLATE_COLOR;
transform.back_color_input[0] = INVALID_INDEX;
transform.back_color_input[1] = INVALID_INDEX;
/* allocate new tokens buffer */
new_tokens = tgsi_alloc_tokens(new_len);
if (!new_tokens)
return NULL;
/* transform the shader */
tgsi_transform_shader(tokens_in, new_tokens, new_len, &transform.base);
return new_tokens;
}
src/gallium/auxiliary/tgsi/tgsi_two_side.h
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@@ -0,0 +1,34 @@
/*
* Copyright 2013 VMware, Inc.
* All Rights Reserved.
*
* 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, sub license, 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 NON-INFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS AND/OR ITS SUPPLIERS 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.
*/
#ifndef TGSI_TWO_SIDE_H
#define TGSI_TWO_SIDE_H
struct tgsi_token;
struct tgsi_token *
tgsi_add_two_side(const struct tgsi_token *tokens_in);
#endif /* TGSI_TWO_SIDE_H */