Function DeformTerrain

Descent3/terrain.cpp:461–531

void UpdateSingleTerrainLightmap(int which);
void DeformTerrain(vector *pos, int depth, float size) {
  int startx, startz, endx, endz;
  int changed[4] = {0, 0, 0, 0};
  vector local_pos = *pos;

  startx = (pos->x / TERRAIN_SIZE) - (size / TERRAIN_SIZE);
  startz = (pos->z / TERRAIN_SIZE) - (size / TERRAIN_SIZE);
  endx = (pos->x / TERRAIN_SIZE) + (size / TERRAIN_SIZE);
  endz = (pos->z / TERRAIN_SIZE) + (size / TERRAIN_SIZE);

  startx = std::max(0, startx);
  startz = std::max(0, startz);
  endx = std::min(TERRAIN_WIDTH - 1, endx);
  endz = std::min(TERRAIN_DEPTH - 1, endz);

  int i, t;

  vector cur_vec;
  vector up_vec = {0, 1, 0};

  local_pos.y = 0;

  cur_vec.x = startx * TERRAIN_SIZE;
  cur_vec.y = 0;
  cur_vec.z = startz * TERRAIN_SIZE;

  float max_dist = vm_VectorDistanceQuick(&local_pos, &cur_vec);

  for (i = startz; i <= endz; i++, cur_vec.z += TERRAIN_SIZE) {
    cur_vec.x = startx * TERRAIN_SIZE;
    for (t = startx; t <= endx; t++, cur_vec.x += TERRAIN_SIZE) {
      terrain_segment *tseg = &Terrain_seg[i * TERRAIN_WIDTH + t];

      if ((up_vec * TerrainNormals[MAX_TERRAIN_LOD - 1][i * TERRAIN_WIDTH + t].normal1) < .5)
        continue; // not flat enough
      if ((up_vec * TerrainNormals[MAX_TERRAIN_LOD - 1][i * TERRAIN_WIDTH + t].normal2) < .5)
        continue; // not flat enough

      float dist = 1.0 - (vm_VectorDistanceQuick(&local_pos, &cur_vec) / max_dist);

      int height_change = -(dist * (float)depth);
      int light_change = height_change * 2;

      DeformTerrainPoint(t, i, height_change);

      tseg->r = std::max(0, tseg->r + light_change);
      tseg->g = std::max(0, tseg->g + light_change);
      tseg->b = std::max(0, tseg->b + light_change);

      int which = ((i / 128) * 2) + (t / 128);
      changed[which] = 1;
    }
  }

  int div = (1 << (MAX_TERRAIN_LOD - 1));

  startx /= div;
  startz /= div;