src/gallium/drivers/llvmpipe/lp_rast_tri.c

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  27
  28 /*
  29  * Rasterization for binned triangles within a tile
  30  */
  31
  32 #include "util/u_math.h"
  33 #include "lp_rast_priv.h"
  34 #include "lp_tile_soa.h"
  35
  36
  37 #define BLOCKSIZE 4
  38
  39
  40 /**
  41  * Add a 4x4 block of pixels to the block list.
  42  * All pixels are known to be inside the triangle's bounds.
  43  */
  44 static void
  45 block_full_4( struct lp_rasterizer *rast, int x, int y )
  46 {
  47    const unsigned i = rast->nr_blocks;
  48    assert(x % 4 == 0);
  49    assert(y % 4 == 0);
  50    rast->blocks[i].x = x;
  51    rast->blocks[i].y = y;
  52    rast->blocks[i].mask = ~0;
  53    rast->nr_blocks++;
  54 }
  55
  56
  57 /**
  58  * Add a 16x16 block of pixels to the block list.
  59  * All pixels are known to be inside the triangle's bounds.
  60  */
  61 static void
  62 block_full_16( struct lp_rasterizer *rast, int x, int y )
  63 {
  64    unsigned ix, iy;
  65    assert(x % 16 == 0);
  66    assert(y % 16 == 0);
  67    for (iy = 0; iy < 16; iy += 4)
  68       for (ix = 0; ix < 16; ix += 4)
  69          block_full_4(rast, x + ix, y + iy);
  70 }
  71
  72
  73 /**
  74  * Evaluate each pixel in a 4x4 block to determine if it lies within
  75  * the triangle's bounds.
  76  * Generate a mask of in/out flags and add the block to the blocks list.
  77  */
  78 static void
  79 do_block_4( struct lp_rasterizer *rast,
  80             const struct lp_rast_triangle *tri,
  81             int x, int y,
  82             int c1,
  83             int c2,
  84             int c3 )
  85 {
  86    int i;
  87    unsigned mask = 0;
  88
  89    assert(x % 4 == 0);
  90    assert(y % 4 == 0);
  91
  92    for (i = 0; i < 16; i++)
  93       mask |= (~(((c1 + tri->step[0][i]) |
  94                   (c2 + tri->step[1][i]) |
  95                   (c3 + tri->step[2][i])) >> 31)) & (1 << i);
  96
  97    /* As we do trivial reject already, masks should rarely be all zero:
  98     */
  99    if (mask) {
 100       const unsigned i = rast->nr_blocks;
 101       rast->blocks[i].x = x;
 102       rast->blocks[i].y = y;
 103       rast->blocks[i].mask = mask;
 104       rast->nr_blocks++;
 105    }
 106 }
 107
 108
 109 /**
 110  * Evaluate a 16x16 block of pixels to determine which 4x4 subblocks are in/out
 111  * of the triangle's bounds.
 112  */
 113 static void
 114 do_block_16( struct lp_rasterizer *rast,
 115              const struct lp_rast_triangle *tri,
 116              int x, int y,
 117              int c1,
 118              int c2,
 119              int c3 )
 120 {
 121    int ix, iy, i = 0;
 122
 123    int ei1 = tri->ei1 << 2;
 124    int ei2 = tri->ei2 << 2;
 125    int ei3 = tri->ei3 << 2;
 126
 127    int eo1 = tri->eo1 << 2;
 128    int eo2 = tri->eo2 << 2;
 129    int eo3 = tri->eo3 << 2;
 130
 131    assert(x % 16 == 0);
 132    assert(y % 16 == 0);
 133
 134    for (iy = 0; iy < 16; iy+=4) {
 135       for (ix = 0; ix < 16; ix+=4, i++) {
 136          int cx1 = c1 + (tri->step[0][i] << 2);
 137          int cx2 = c2 + (tri->step[1][i] << 2);
 138          int cx3 = c3 + (tri->step[2][i] << 2);
 139
 140          if (cx1 + eo1 < 0 ||
 141              cx2 + eo2 < 0 ||
 142              cx3 + eo3 < 0) {
 143             /* the block is completely outside the triangle - nop */
 144          }
 145          else if (cx1 + ei1 > 0 &&
 146                   cx2 + ei2 > 0 &&
 147                   cx3 + ei3 > 0) {
 148             /* the block is completely inside the triangle */
 149             block_full_4(rast, x+ix, y+iy);
 150          }
 151          else {
 152             /* the block is partially in/out of the triangle */
 153             do_block_4(rast, tri, x+ix, y+iy, cx1, cx2, cx3);
 154          }
 155       }
 156    }
 157 }
 158
 159
 160 /**
 161  * Scan the tile in chunks and figure out which pixels to rasterize
 162  * for this triangle.
 163  */
 164 void
 165 lp_rast_triangle( struct lp_rasterizer *rast,
 166                   const union lp_rast_cmd_arg arg )
 167 {
 168    const struct lp_rast_triangle *tri = arg.triangle;
 169
 170    int x = rast->x;
 171    int y = rast->y;
 172    int ix, iy;
 173    unsigned i = 0;
 174
 175    int c1 = tri->c1 + tri->dx12 * y - tri->dy12 * x;
 176    int c2 = tri->c2 + tri->dx23 * y - tri->dy23 * x;
 177    int c3 = tri->c3 + tri->dx31 * y - tri->dy31 * x;
 178
 179    int ei1 = tri->ei1 << 4;
 180    int ei2 = tri->ei2 << 4;
 181    int ei3 = tri->ei3 << 4;
 182
 183    int eo1 = tri->eo1 << 4;
 184    int eo2 = tri->eo2 << 4;
 185    int eo3 = tri->eo3 << 4;
 186
 187    debug_printf("%s\n", __FUNCTION__);
 188
 189    rast->nr_blocks = 0;
 190
 191    /* Walk over the tile to build a list of 4x4 pixel blocks which will
 192     * be filled/shaded.  We do this at two granularities: 16x16 blocks
 193     * and then 4x4 blocks.
 194     */
 195    for (iy = 0; iy < TILE_SIZE; iy += 16) {
 196       for (ix = 0; ix < TILE_SIZE; ix += 16, i++) {
 197          int cx1 = c1 + (tri->step[0][i] << 4);
 198          int cx2 = c2 + (tri->step[1][i] << 4);
 199          int cx3 = c3 + (tri->step[2][i] << 4);
 200
 201          if (cx1 + eo1 < 0 ||
 202              cx2 + eo2 < 0 ||
 203              cx3 + eo3 < 0) {
 204             /* the block is completely outside the triangle - nop */
 205          }
 206          else if (cx1 + ei1 > 0 &&
 207                   cx2 + ei2 > 0 &&
 208                   cx3 + ei3 > 0) {
 209             /* the block is completely inside the triangle */
 210             block_full_16(rast, x+ix, y+iy);
 211          }
 212          else {
 213             /* the block is partially in/out of the triangle */
 214             do_block_16(rast, tri, x+ix, y+iy, cx1, cx2, cx3);
 215          }
 216       }
 217    }
 218
 219    /* Shade the 4x4 pixel blocks */
 220    for (i = 0; i < rast->nr_blocks; i++)
 221       lp_rast_shade_quads(rast, &tri->inputs,
 222                           rast->blocks[i].x,
 223                           rast->blocks[i].y,
 224                           rast->blocks[i].mask);
 225 }