Function DrawTerrainTrianglesHardware

Descent3/terrainrender.cpp:2899–3150

Draws the 2 triangles of the Terrainlist[index] (hardware)

}
// Draws the 2 triangles of the Terrainlist[index] (hardware)
int DrawTerrainTrianglesHardware(int index, int bm_handle, int upper_left, int lower_right) {
  int i;
  int cur_seg;
  int n = Terrain_list[index].segment;
  int lod = Terrain_list[index].lod;
  int bottom_start, left_start, right_start;
  int point_count = 0;
  int points_this_triangle = 0;

  terrain_segment *tseg = &Terrain_seg[n];
  terrain_tex_segment *texseg = &Terrain_tex_seg[tseg->texseg_index];
  int rotator = texseg->rotation & 0x0F;
  int tile = texseg->rotation >> 4;
  int simplemul = 1 << ((MAX_TERRAIN_LOD - 1) - lod);
  int cx, cz, smul_x, smul_z;
  cx = n % TERRAIN_WIDTH;
  cz = n / TERRAIN_WIDTH;

  // Get lightmap coordinates
  float lightmap_u = (cx % 128) / 128.0;
  float lightmap_v = (128 - ((cz % 128) + simplemul)) / 128.0;
  float uvadjust;
  int draw_big_square = 0;
  int subx = cx % MAX_LOD_SIZE;
  int subz = (MAX_LOD_SIZE - 1) - ((cz + (simplemul - 1)) % MAX_LOD_SIZE);
  bool solid_square = 1;
  int testt = 0, testr = 0, testb = 0, testl = 0;
  // Check to make sure we don't access memory that is off the map
  if (cx + simplemul == TERRAIN_WIDTH) {
    smul_x = simplemul - 1;
    solid_square = 0;
  } else
    smul_x = simplemul;
  if (cz + simplemul == TERRAIN_DEPTH) {
    solid_square = 0;
    smul_z = simplemul - 1;
  } else
    smul_z = simplemul;
  // Build a list of points for our polygon.  We must do it this way to
  // prevent tjoint cracking
  // Do simpler operation if at highest level of detail
  if (lod == (MAX_TERRAIN_LOD - 1)) {
    uvadjust = (simplemul / 128.0);
    cur_seg = n + (TERRAIN_WIDTH * smul_z);
    base[0] = World_point_buffer[cur_seg];

    cur_seg = n + (TERRAIN_WIDTH * smul_z) + smul_x;
    base[1] = World_point_buffer[cur_seg];

    cur_seg = n + smul_x;
    base[2] = World_point_buffer[cur_seg];

    base[3] = World_point_buffer[n];

    base[0].p3_u = tile * TerrainUSpeedup[rotator][subz * LOD_ROW_SIZE + subx];
    base[0].p3_v = tile * TerrainVSpeedup[rotator][subz * LOD_ROW_SIZE + subx];
    base[1].p3_u = tile * TerrainUSpeedup[rotator][subz * LOD_ROW_SIZE + subx + 1];
    base[1].p3_v = tile * TerrainVSpeedup[rotator][subz * LOD_ROW_SIZE + subx + 1];