src/gallium/drivers/llvmpipe/lp_rast_tri.c

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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, &tri->inputs, x, y);
  97 }
  98
  99
 100 /**
 101  * Shade all pixels in a 16x16 block.
 102  */
 103 static void
 104 block_full_16( struct lp_rasterizer_task *rast_task,
 105                const struct lp_rast_triangle *tri,
 106                int x, int y )
 107 {
 108    unsigned ix, iy;
 109    assert(x % 16 == 0);
 110    assert(y % 16 == 0);
 111    for (iy = 0; iy < 16; iy += 4)
 112       for (ix = 0; ix < 16; ix += 4)
 113          block_full_4(rast_task, tri, x + ix, y + iy);
 114 }
 115
 116
 117 /**
 118  * Pass the 4x4 pixel block to the shader function.
 119  * Determination of which of the 16 pixels lies inside the triangle
 120  * will be done as part of the fragment shader.
 121  */
 122 static void
 123 do_block_4( struct lp_rasterizer_task *rast_task,
 124             const struct lp_rast_triangle *tri,
 125             int x, int y,
 126             int c1,
 127             int c2,
 128             int c3 )
 129 {
 130    assert(x >= 0);
 131    assert(y >= 0);
 132
 133    lp_rast_shade_quads(rast_task,
 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 c0,
 149              int c1,
 150              int c2 )
 151 {
 152    unsigned mask = 0;
 153    int eo[3];
 154    int c[3];
 155    int i, j;
 156
 157    assert(x >= 0);
 158    assert(y >= 0);
 159    assert(x % 16 == 0);
 160    assert(y % 16 == 0);
 161
 162    eo[0] = tri->eo1 * 4;
 163    eo[1] = tri->eo2 * 4;
 164    eo[2] = tri->eo3 * 4;
 165
 166    c[0] = c0;
 167    c[1] = c1;
 168    c[2] = c2;
 169
 170    for (j = 0; j < 3; j++) {
 171       const int *step = tri->inputs.step[j];
 172       const int cx = c[j] + 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;
 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    int ei[3], eo[3], c[3];
 217    unsigned outmask, inmask, partial_mask;
 218    unsigned i, j;
 219
 220    c[0] = tri->c1 + tri->dx12 * y - tri->dy12 * x;
 221    c[1] = tri->c2 + tri->dx23 * y - tri->dy23 * x;
 222    c[2] = tri->c3 + tri->dx31 * y - tri->dy31 * x;
 223
 224    eo[0] = tri->eo1 * 16;
 225    eo[1] = tri->eo2 * 16;
 226    eo[2] = tri->eo3 * 16;
 227
 228    ei[0] = tri->ei1 * 16;
 229    ei[1] = tri->ei2 * 16;
 230    ei[2] = tri->ei3 * 16;
 231
 232    outmask = 0;
 233    inmask = 0xffff;
 234
 235    for (j = 0; j < 3; j++) {
 236       const int *step = tri->inputs.step[j];
 237       const int cox = c[j] + eo[j];
 238       const int cio = ei[j]- eo[j];
 239
 240       /* Outmask has bits set whenever we are outside any of the
 241        * edges.
 242        */
 243       /* Inmask has bits set whenever we are inside all of the edges.
 244        */
 245       for (i = 0; i < 16; i++) {
 246          int out = cox + step[i] * 16;
 247          int in = out + cio;
 248          outmask |= (out >> 31) & (1 << i);
 249          inmask &= ~((in >> 31) & (1 << i));
 250       }
 251    }
 252
 253    assert((outmask & inmask) == 0);
 254
 255    if (outmask == 0xffff)
 256       return;
 257
 258    /* Invert mask, so that bits are set whenever we are at least
 259     * partially inside all of the edges:
 260     */
 261    partial_mask = ~inmask & ~outmask & 0xffff;
 262
 263    /* Iterate over partials:
 264     */
 265    while (partial_mask) {
 266       int i = ffs(partial_mask) - 1;
 267       int px = x + pos_table16[i][0];
 268       int py = y + pos_table16[i][1];
 269       int cx1 = c[0] + tri->inputs.step[0][i] * 16;
 270       int cx2 = c[1] + tri->inputs.step[1][i] * 16;
 271       int cx3 = c[2] + tri->inputs.step[2][i] * 16;
 272
 273       partial_mask &= ~(1 << i);
 274
 275       LP_COUNT(nr_partially_covered_16);
 276       do_block_16(rast_task, tri, px, py, cx1, cx2, cx3);
 277    }
 278
 279    /* Iterate over fulls:
 280     */
 281    while (inmask) {
 282       int i = ffs(inmask) - 1;
 283       int px = x + pos_table16[i][0];
 284       int py = y + pos_table16[i][1];
 285
 286       inmask &= ~(1 << i);
 287
 288       LP_COUNT(nr_fully_covered_16);
 289       block_full_16(rast_task, tri, px, py);
 290    }
 291 }