src/gallium/drivers/llvmpipe/lp_rast_tri.c

   1 /**************************************************************************
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   3  * Copyright 2007-2009 VMware, Inc.
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  15  * next paragraph) shall be included in all copies or substantial portions
  16  * of the Software.
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  27
  28 /*
  29  * Rasterization for binned triangles within a tile
  30  */
  31
  32 #include <limits.h>
  33 #include "util/u_math.h"
  34 #include "lp_debug.h"
  35 #include "lp_rast_priv.h"
  36 #include "lp_tile_soa.h"
  37
  38
  39 /**
  40  * Map an index in [0,15] to an x,y position, multiplied by 4.
  41  * This is used to get the position of each subtile in a 4x4
  42  * grid of edge step values.
  43  */
  44 static const int pos_table4[16][2] = {
  45    { 0, 0 },
  46    { 4, 0 },
  47    { 0, 4 },
  48    { 4, 4 },
  49    { 8, 0 },
  50    { 12, 0 },
  51    { 8, 4 },
  52    { 12, 4 },
  53    { 0, 8 },
  54    { 4, 8 },
  55    { 0, 12 },
  56    { 4, 12 },
  57    { 8, 8 },
  58    { 12, 8 },
  59    { 8, 12 },
  60    { 12, 12 }
  61 };
  62
  63
  64 static const int pos_table16[16][2] = {
  65    { 0, 0 },
  66    { 16, 0 },
  67    { 0, 16 },
  68    { 16, 16 },
  69    { 32, 0 },
  70    { 48, 0 },
  71    { 32, 16 },
  72    { 48, 16 },
  73    { 0, 32 },
  74    { 16, 32 },
  75    { 0, 48 },
  76    { 16, 48 },
  77    { 32, 32 },
  78    { 48, 32 },
  79    { 32, 48 },
  80    { 48, 48 }
  81 };
  82
  83
  84 /**
  85  * Shade all pixels in a 4x4 block.
  86  */
  87 static void
  88 block_full_4( struct lp_rasterizer_task *rast_task,
  89               const struct lp_rast_triangle *tri,
  90               int x, int y )
  91 {
  92    /* Set c1,c2,c3 to large values so the in/out test always passes */
  93    const int32_t c1 = INT_MIN/2, c2 = INT_MIN/2, c3 = INT_MIN/2;
  94    lp_rast_shade_quads(rast_task->rast,
  95                        rast_task->thread_index,
  96                        &tri->inputs,
  97                        x, y,
  98                        c1, c2, c3);
  99 }
 100
 101
 102 /**
 103  * Shade all pixels in a 16x16 block.
 104  */
 105 static void
 106 block_full_16( struct lp_rasterizer_task *rast_task,
 107                const struct lp_rast_triangle *tri,
 108                int x, int y )
 109 {
 110    unsigned ix, iy;
 111    assert(x % 16 == 0);
 112    assert(y % 16 == 0);
 113    for (iy = 0; iy < 16; iy += 4)
 114       for (ix = 0; ix < 16; ix += 4)
 115          block_full_4(rast_task, tri, x + ix, y + iy);
 116 }
 117
 118
 119 /**
 120  * Pass the 4x4 pixel block to the shader function.
 121  * Determination of which of the 16 pixels lies inside the triangle
 122  * will be done as part of the fragment shader.
 123  */
 124 static void
 125 do_block_4( struct lp_rasterizer_task *rast_task,
 126             const struct lp_rast_triangle *tri,
 127             int x, int y,
 128             int c1,
 129             int c2,
 130             int c3 )
 131 {
 132    lp_rast_shade_quads(rast_task->rast,
 133                        rast_task->thread_index,
 134                        &tri->inputs,
 135                        x, y,
 136                        -c1, -c2, -c3);
 137 }
 138
 139
 140 /**
 141  * Evaluate a 16x16 block of pixels to determine which 4x4 subblocks are in/out
 142  * of the triangle's bounds.
 143  */
 144 static void
 145 do_block_16( struct lp_rasterizer_task *rast_task,
 146              const struct lp_rast_triangle *tri,
 147              int x, int y,
 148              int c1,
 149              int c2,
 150              int c3 )
 151 {
 152    const int ei1 = tri->ei1 * 4;
 153    const int ei2 = tri->ei2 * 4;
 154    const int ei3 = tri->ei3 * 4;
 155
 156    const int eo1 = tri->eo1 * 4;
 157    const int eo2 = tri->eo2 * 4;
 158    const int eo3 = tri->eo3 * 4;
 159
 160    int i;
 161
 162    assert(x % 16 == 0);
 163    assert(y % 16 == 0);
 164
 165    for (i = 0; i < 16; i++) {
 166       int cx1 = c1 + (tri->inputs.step[0][i] * 4);
 167       int cx2 = c2 + (tri->inputs.step[1][i] * 4);
 168       int cx3 = c3 + (tri->inputs.step[2][i] * 4);
 169
 170       if (cx1 + eo1 < 0 ||
 171           cx2 + eo2 < 0 ||
 172           cx3 + eo3 < 0) {
 173          /* the block is completely outside the triangle - nop */
 174       }
 175       else {
 176          int px = x + pos_table4[i][0];
 177          int py = y + pos_table4[i][1];
 178          if (cx1 + ei1 > 0 &&
 179              cx2 + ei2 > 0 &&
 180              cx3 + ei3 > 0) {
 181             /* the block is completely inside the triangle */
 182             block_full_4(rast_task, tri, px, py);
 183          }
 184          else {
 185             /* the block is partially in/out of the triangle */
 186             do_block_4(rast_task, tri, px, py, cx1, cx2, cx3);
 187          }
 188       }
 189    }
 190 }
 191
 192
 193 /**
 194  * Scan the tile in chunks and figure out which pixels to rasterize
 195  * for this triangle.
 196  */
 197 void
 198 lp_rast_triangle( struct lp_rasterizer *rast,
 199                   unsigned thread_index,
 200                   const union lp_rast_cmd_arg arg )
 201 {
 202    struct lp_rasterizer_task *rast_task = &rast->tasks[thread_index];
 203    const struct lp_rast_triangle *tri = arg.triangle;
 204
 205    int x = rast_task->x;
 206    int y = rast_task->y;
 207    unsigned i;
 208
 209    int c1 = tri->c1 + tri->dx12 * y - tri->dy12 * x;
 210    int c2 = tri->c2 + tri->dx23 * y - tri->dy23 * x;
 211    int c3 = tri->c3 + tri->dx31 * y - tri->dy31 * x;
 212
 213    int ei1 = tri->ei1 * 16;
 214    int ei2 = tri->ei2 * 16;
 215    int ei3 = tri->ei3 * 16;
 216
 217    int eo1 = tri->eo1 * 16;
 218    int eo2 = tri->eo2 * 16;
 219    int eo3 = tri->eo3 * 16;
 220
 221    LP_DBG(DEBUG_RAST, "lp_rast_triangle\n");
 222
 223    /* Walk over the tile to build a list of 4x4 pixel blocks which will
 224     * be filled/shaded.  We do this at two granularities: 16x16 blocks
 225     * and then 4x4 blocks.
 226     */
 227    for (i = 0; i < 16; i++) {
 228       int cx1 = c1 + (tri->inputs.step[0][i] * 16);
 229       int cx2 = c2 + (tri->inputs.step[1][i] * 16);
 230       int cx3 = c3 + (tri->inputs.step[2][i] * 16);
 231
 232       if (cx1 + eo1 < 0 ||
 233           cx2 + eo2 < 0 ||
 234           cx3 + eo3 < 0) {
 235          /* the block is completely outside the triangle - nop */
 236       }
 237       else {
 238          int px = x + pos_table16[i][0];
 239          int py = y + pos_table16[i][1];
 240
 241          if (cx1 + ei1 > 0 &&
 242              cx2 + ei2 > 0 &&
 243              cx3 + ei3 > 0) {
 244             /* the block is completely inside the triangle */
 245             block_full_16(rast_task, tri, px, py);
 246          }
 247          else {
 248             /* the block is partially in/out of the triangle */
 249             do_block_16(rast_task, tri, px, py, cx1, cx2, cx3);
 250          }
 251       }
 252    }
 253 }