src/gallium/drivers/llvmpipe/lp_rast_tri.c

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   3  * Copyright 2007-2009 VMware, Inc.
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  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_perf.h"
  36 #include "lp_rast_priv.h"
  37 #include "lp_tile_soa.h"
  38
  39
  40 /**
  41  * Map an index in [0,15] to an x,y position, multiplied by 4.
  42  * This is used to get the position of each subtile in a 4x4
  43  * grid of edge step values.
  44  * Note: we can use some bit twiddling to compute these values instead
  45  * of using a look-up table, but there's no measurable performance
  46  * difference.
  47  */
  48 static const int pos_table4[16][2] = {
  49    { 0, 0 },
  50    { 4, 0 },
  51    { 0, 4 },
  52    { 4, 4 },
  53    { 8, 0 },
  54    { 12, 0 },
  55    { 8, 4 },
  56    { 12, 4 },
  57    { 0, 8 },
  58    { 4, 8 },
  59    { 0, 12 },
  60    { 4, 12 },
  61    { 8, 8 },
  62    { 12, 8 },
  63    { 8, 12 },
  64    { 12, 12 }
  65 };
  66
  67
  68 static const int pos_table16[16][2] = {
  69    { 0, 0 },
  70    { 16, 0 },
  71    { 0, 16 },
  72    { 16, 16 },
  73    { 32, 0 },
  74    { 48, 0 },
  75    { 32, 16 },
  76    { 48, 16 },
  77    { 0, 32 },
  78    { 16, 32 },
  79    { 0, 48 },
  80    { 16, 48 },
  81    { 32, 32 },
  82    { 48, 32 },
  83    { 32, 48 },
  84    { 48, 48 }
  85 };
  86
  87
  88 /**
  89  * Shade all pixels in a 4x4 block.
  90  */
  91 static void
  92 block_full_4( struct lp_rasterizer_task *rast_task,
  93               const struct lp_rast_triangle *tri,
  94               int x, int y )
  95 {
  96    lp_rast_shade_quads_all(rast_task->rast,
  97                            rast_task->thread_index,
  98                            &tri->inputs,
  99                            x, y);
 100 }
 101
 102
 103 /**
 104  * Shade all pixels in a 16x16 block.
 105  */
 106 static void
 107 block_full_16( struct lp_rasterizer_task *rast_task,
 108                const struct lp_rast_triangle *tri,
 109                int x, int y )
 110 {
 111    unsigned ix, iy;
 112    assert(x % 16 == 0);
 113    assert(y % 16 == 0);
 114    for (iy = 0; iy < 16; iy += 4)
 115       for (ix = 0; ix < 16; ix += 4)
 116          block_full_4(rast_task, tri, x + ix, y + iy);
 117 }
 118
 119
 120 /**
 121  * Pass the 4x4 pixel block to the shader function.
 122  * Determination of which of the 16 pixels lies inside the triangle
 123  * will be done as part of the fragment shader.
 124  */
 125 static void
 126 do_block_4( struct lp_rasterizer_task *rast_task,
 127             const struct lp_rast_triangle *tri,
 128             int x, int y,
 129             int c1,
 130             int c2,
 131             int c3 )
 132 {
 133    lp_rast_shade_quads(rast_task->rast,
 134                        rast_task->thread_index,
 135                        &tri->inputs,
 136                        x, y,
 137                        -c1, -c2, -c3);
 138 }
 139
 140
 141 /**
 142  * Evaluate a 16x16 block of pixels to determine which 4x4 subblocks are in/out
 143  * of the triangle's bounds.
 144  */
 145 static void
 146 do_block_16( struct lp_rasterizer_task *rast_task,
 147              const struct lp_rast_triangle *tri,
 148              int x, int y,
 149              int c0,
 150              int c1,
 151              int c2 )
 152 {
 153    unsigned mask = 0;
 154    int eo[3];
 155    int c[3];
 156    int i, j;
 157
 158    assert(x % 16 == 0);
 159    assert(y % 16 == 0);
 160
 161    eo[0] = tri->eo1 * 4;
 162    eo[1] = tri->eo2 * 4;
 163    eo[2] = tri->eo3 * 4;
 164
 165    c[0] = c0;
 166    c[1] = c1;
 167    c[2] = c2;
 168
 169    for (j = 0; j < 3; j++) {
 170       const int *step = tri->inputs.step[j];
 171       int cx = c[j];
 172       int eox = eo[j];
 173
 174       /* Mask has bits set whenever we are outside any of the edges.
 175        */
 176       for (i = 0; i < 16; i++) {
 177          int out = cx + step[i] * 4 + eox;
 178          mask |= (out >> 31) & (1 << i);
 179       }
 180    }
 181
 182    mask = ~mask & 0xffff;
 183    while (mask) {
 184       int i = ffs(mask) - 1;
 185       int px = x + pos_table4[i][0];
 186       int py = y + pos_table4[i][1];
 187       int cx1 = c0 + tri->inputs.step[0][i] * 4;
 188       int cx2 = c1 + tri->inputs.step[1][i] * 4;
 189       int cx3 = c2 + tri->inputs.step[2][i] * 4;
 190
 191       mask &= ~(1 << i);
 192
 193       /* Don't bother testing if the 4x4 block is entirely in/out of
 194        * the triangle.  It's a little faster to do it in the jit code.
 195        */
 196       LP_COUNT(nr_non_empty_4);
 197       do_block_4(rast_task, tri, px, py, cx1, cx2, cx3);
 198    }
 199 }
 200
 201
 202 /**
 203  * Scan the tile in chunks and figure out which pixels to rasterize
 204  * for this triangle.
 205  */
 206 void
 207 lp_rast_triangle( struct lp_rasterizer *rast,
 208                   unsigned thread_index,
 209                   const union lp_rast_cmd_arg arg )
 210 {
 211    struct lp_rasterizer_task *rast_task = &rast->tasks[thread_index];
 212    const struct lp_rast_triangle *tri = arg.triangle;
 213
 214    int x = rast_task->x;
 215    int y = rast_task->y;
 216    unsigned i;
 217
 218    int c1 = tri->c1 + tri->dx12 * y - tri->dy12 * x;
 219    int c2 = tri->c2 + tri->dx23 * y - tri->dy23 * x;
 220    int c3 = tri->c3 + tri->dx31 * y - tri->dy31 * x;
 221
 222    int ei1 = tri->ei1 * 16;
 223    int ei2 = tri->ei2 * 16;
 224    int ei3 = tri->ei3 * 16;
 225
 226    int eo1 = tri->eo1 * 16;
 227    int eo2 = tri->eo2 * 16;
 228    int eo3 = tri->eo3 * 16;
 229
 230    LP_DBG(DEBUG_RAST, "lp_rast_triangle\n");
 231
 232    /* Walk over the tile to build a list of 4x4 pixel blocks which will
 233     * be filled/shaded.  We do this at two granularities: 16x16 blocks
 234     * and then 4x4 blocks.
 235     */
 236    for (i = 0; i < 16; i++) {
 237       int cx1 = c1 + (tri->inputs.step[0][i] * 16);
 238       int cx2 = c2 + (tri->inputs.step[1][i] * 16);
 239       int cx3 = c3 + (tri->inputs.step[2][i] * 16);
 240
 241       if (cx1 + eo1 < 0 ||
 242           cx2 + eo2 < 0 ||
 243           cx3 + eo3 < 0) {
 244          /* the block is completely outside the triangle - nop */
 245          LP_COUNT(nr_empty_16);
 246       }
 247       else {
 248          int px = x + pos_table16[i][0];
 249          int py = y + pos_table16[i][1];
 250
 251          if (cx1 + ei1 > 0 &&
 252              cx2 + ei2 > 0 &&
 253              cx3 + ei3 > 0) {
 254             /* the block is completely inside the triangle */
 255             LP_COUNT(nr_fully_covered_16);
 256             block_full_16(rast_task, tri, px, py);
 257          }
 258          else {
 259             /* the block is partially in/out of the triangle */
 260             LP_COUNT(nr_partially_covered_16);
 261             do_block_16(rast_task, tri, px, py, cx1, cx2, cx3);
 262          }
 263       }
 264    }
 265 }