Function BuildNormalForTerrainSegment

Descent3/terrain.cpp:1126–1164

Builds the surface normal for terrain segment n

// Builds the surface normal for terrain segment n
void BuildNormalForTerrainSegment(int n) {
  int i, t;

  vector a, b, c;

  if (n < 0 || n >= (TERRAIN_WIDTH - 1) * (TERRAIN_DEPTH - 1))
    return;

  i = n / TERRAIN_WIDTH;
  t = n % TERRAIN_WIDTH;

  a.x = t * TERRAIN_SIZE;
  a.y = Terrain_seg[(i * TERRAIN_WIDTH) + (t)].y;
  a.z = i * TERRAIN_SIZE;

  b.x = t * TERRAIN_SIZE;
  b.y = Terrain_seg[(i * TERRAIN_WIDTH) + (t + TERRAIN_WIDTH)].y;
  b.z = (i + 1) * TERRAIN_SIZE;

  c.x = (t + 1) * TERRAIN_SIZE;
  c.y = Terrain_seg[(i * TERRAIN_WIDTH) + (t + TERRAIN_WIDTH + 1)].y;
  c.z = (i + 1) * TERRAIN_SIZE;

  vm_GetNormal(&TerrainNormals[MAX_TERRAIN_LOD - 1][i * TERRAIN_WIDTH + t].normal1, &a, &b, &c);

  a.x = t * TERRAIN_SIZE;
  a.y = Terrain_seg[(i * TERRAIN_WIDTH) + (t)].y;
  a.z = i * TERRAIN_SIZE;

  b.x = (t + 1) * TERRAIN_SIZE;
  b.y = Terrain_seg[(i * TERRAIN_WIDTH) + (t + TERRAIN_WIDTH + 1)].y;
  b.z = (i + 1) * TERRAIN_SIZE;

  c.x = (t + 1) * TERRAIN_SIZE;
  c.y = Terrain_seg[(i * TERRAIN_WIDTH) + (t + 1)].y;
  c.z = (i)*TERRAIN_SIZE;

  vm_GetNormal(&TerrainNormals[MAX_TERRAIN_LOD - 1][i * TERRAIN_WIDTH + t].normal2, &a, &b, &c);
}

// Builds the vertex normal for terrain segment n
void BuildLightingNormalForSegment(int n) {