1/*
2 * Copyright 2013 VMware, Inc.
3 * All Rights Reserved.
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining a
6 * copy of this software and associated documentation files (the
7 * "Software"), to deal in the Software without restriction, including
8 * without limitation the rights to use, copy, modify, merge, publish,
9 * distribute, sub license, and/or sell copies of the Software, and to
10 * permit persons to whom the Software is furnished to do so, subject to
11 * the following conditions:
12 *
13 * The above copyright notice and this permission notice (including the
14 * next paragraph) shall be included in all copies or substantial portions
15 * of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
18 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
19 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
20 * IN NO EVENT SHALL THE AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR
21 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
22 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
23 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
24 */
25
26
27/**
28 * This utility transforms fragment shaders to facilitate two-sided lighting.
29 *
30 * Basically, if the FS has any color inputs (TGSI_SEMANTIC_COLOR) we'll:
31 * 1. create corresponding back-color inputs (TGSI_SEMANTIC_BCOLOR)
32 * 2. use the FACE register to choose between front/back colors and put the
33 *    selected color in new temp regs.
34 * 3. replace reads of the original color inputs with the new temp regs.
35 *
36 * Then, the driver just needs to link the VS front/back output colors to
37 * the FS front/back input colors.
38 */
39
40#include "util/u_debug.h"
41#include "util/u_math.h"
42#include "tgsi_info.h"
43#include "tgsi_two_side.h"
44#include "tgsi_transform.h"
45
46
47#define INVALID_INDEX 9999
48
49
50struct two_side_transform_context
51{
52   struct tgsi_transform_context base;
53   uint num_temps;
54   uint num_inputs;
55   uint face_input;           /**< index of the FACE input */
56   uint front_color_input[2]; /**< INPUT regs */
57   uint front_color_interp[2];/**< TGSI_INTERPOLATE_x */
58   uint back_color_input[2];  /**< INPUT regs */
59   uint new_colors[2];        /**< TEMP regs */
60};
61
62
63static inline struct two_side_transform_context *
64two_side_transform_context(struct tgsi_transform_context *ctx)
65{
66   return (struct two_side_transform_context *) ctx;
67}
68
69
70static void
71xform_decl(struct tgsi_transform_context *ctx,
72           struct tgsi_full_declaration *decl)
73{
74   struct two_side_transform_context *ts = two_side_transform_context(ctx);
75
76   if (decl->Declaration.File == TGSI_FILE_INPUT) {
77      if (decl->Semantic.Name == TGSI_SEMANTIC_COLOR) {
78         /* found a front color */
79         assert(decl->Semantic.Index < 2);
80         ts->front_color_input[decl->Semantic.Index] = decl->Range.First;
81         ts->front_color_interp[decl->Semantic.Index] = decl->Interp.Interpolate;
82      }
83      else if (decl->Semantic.Name == TGSI_SEMANTIC_FACE) {
84         ts->face_input = decl->Range.First;
85      }
86      ts->num_inputs = MAX2(ts->num_inputs, decl->Range.Last + 1);
87   }
88   else if (decl->Declaration.File == TGSI_FILE_TEMPORARY) {
89      ts->num_temps = MAX2(ts->num_temps, decl->Range.Last + 1);
90   }
91
92   ctx->emit_declaration(ctx, decl);
93}
94
95
96static void
97emit_prolog(struct tgsi_transform_context *ctx)
98{
99   struct two_side_transform_context *ts = two_side_transform_context(ctx);
100   struct tgsi_full_declaration decl;
101   struct tgsi_full_instruction inst;
102   uint num_colors = 0;
103   uint i;
104
105   /* Declare 0, 1 or 2 new BCOLOR inputs */
106   for (i = 0; i < 2; i++) {
107      if (ts->front_color_input[i] != INVALID_INDEX) {
108         decl = tgsi_default_full_declaration();
109         decl.Declaration.File = TGSI_FILE_INPUT;
110         decl.Declaration.Interpolate = 1;
111         decl.Declaration.Semantic = 1;
112         decl.Semantic.Name = TGSI_SEMANTIC_BCOLOR;
113         decl.Semantic.Index = i;
114         decl.Range.First = decl.Range.Last = ts->num_inputs++;
115         decl.Interp.Interpolate = ts->front_color_interp[i];
116         ctx->emit_declaration(ctx, &decl);
117         ts->back_color_input[i] = decl.Range.First;
118         num_colors++;
119      }
120   }
121
122   if (num_colors > 0) {
123      /* Declare 1 or 2 temp registers */
124      decl = tgsi_default_full_declaration();
125      decl.Declaration.File = TGSI_FILE_TEMPORARY;
126      decl.Range.First = ts->num_temps;
127      decl.Range.Last = ts->num_temps + num_colors - 1;
128      ctx->emit_declaration(ctx, &decl);
129      ts->new_colors[0] = ts->num_temps;
130      ts->new_colors[1] = ts->num_temps + 1;
131
132      if (ts->face_input == INVALID_INDEX) {
133         /* declare FACE INPUT register */
134         decl = tgsi_default_full_declaration();
135         decl.Declaration.File = TGSI_FILE_INPUT;
136         decl.Declaration.Semantic = 1;
137         decl.Semantic.Name = TGSI_SEMANTIC_FACE;
138         decl.Semantic.Index = 0;
139         decl.Range.First = decl.Range.Last = ts->num_inputs++;
140         ctx->emit_declaration(ctx, &decl);
141         ts->face_input = decl.Range.First;
142      }
143
144      /* CMP temp[c0], face, bcolor[c0], fcolor[c0]
145       * temp[c0] = face < 0.0 ? bcolor[c0] : fcolor[c0]
146       */
147      for (i = 0; i < 2; i++) {
148         if (ts->front_color_input[i] != INVALID_INDEX) {
149            inst = tgsi_default_full_instruction();
150            inst.Instruction.Opcode = TGSI_OPCODE_CMP;
151            inst.Instruction.NumDstRegs = 1;
152            inst.Dst[0].Register.File = TGSI_FILE_TEMPORARY;
153            inst.Dst[0].Register.Index = ts->new_colors[i];
154            inst.Instruction.NumSrcRegs = 3;
155            inst.Src[0].Register.File = TGSI_FILE_INPUT;
156            inst.Src[0].Register.Index = ts->face_input;
157            inst.Src[1].Register.File = TGSI_FILE_INPUT;
158            inst.Src[1].Register.Index = ts->back_color_input[i];
159            inst.Src[2].Register.File = TGSI_FILE_INPUT;
160            inst.Src[2].Register.Index = ts->front_color_input[i];
161
162            ctx->emit_instruction(ctx, &inst);
163         }
164      }
165   }
166}
167
168
169static void
170xform_inst(struct tgsi_transform_context *ctx,
171           struct tgsi_full_instruction *inst)
172{
173   struct two_side_transform_context *ts = two_side_transform_context(ctx);
174   const struct tgsi_opcode_info *info =
175      tgsi_get_opcode_info(inst->Instruction.Opcode);
176   uint i, j;
177
178   /* Look for src regs which reference the input color and replace
179    * them with the temp color.
180    */
181   for (i = 0; i < info->num_src; i++) {
182      if (inst->Src[i].Register.File == TGSI_FILE_INPUT) {
183         for (j = 0; j < 2; j++) {
184            if (inst->Src[i].Register.Index == ts->front_color_input[j]) {
185               /* replace color input with temp reg */
186               inst->Src[i].Register.File = TGSI_FILE_TEMPORARY;
187               inst->Src[i].Register.Index = ts->new_colors[j];
188               break;
189            }
190         }
191      }
192   }
193
194   ctx->emit_instruction(ctx, inst);
195}
196
197
198struct tgsi_token *
199tgsi_add_two_side(const struct tgsi_token *tokens_in)
200{
201   struct two_side_transform_context transform;
202   const uint num_new_tokens = 100; /* should be enough */
203   const uint new_len = tgsi_num_tokens(tokens_in) + num_new_tokens;
204   struct tgsi_token *new_tokens;
205
206   /* setup transformation context */
207   memset(&transform, 0, sizeof(transform));
208   transform.base.transform_declaration = xform_decl;
209   transform.base.transform_instruction = xform_inst;
210   transform.base.prolog = emit_prolog;
211   transform.face_input = INVALID_INDEX;
212   transform.front_color_input[0] = INVALID_INDEX;
213   transform.front_color_input[1] = INVALID_INDEX;
214   transform.front_color_interp[0] = TGSI_INTERPOLATE_COLOR;
215   transform.front_color_interp[1] = TGSI_INTERPOLATE_COLOR;
216   transform.back_color_input[0] = INVALID_INDEX;
217   transform.back_color_input[1] = INVALID_INDEX;
218
219   /* allocate new tokens buffer */
220   new_tokens = tgsi_alloc_tokens(new_len);
221   if (!new_tokens)
222      return NULL;
223
224   /* transform the shader */
225   tgsi_transform_shader(tokens_in, new_tokens, new_len, &transform.base);
226
227   return new_tokens;
228}
229