void Tile::draw(const Mercator::Terrain & h, int x, int y)
{
if (tex_id == -1) { return; }
glBindTexture(GL_TEXTURE_2D, tex_id);
glEnable(GL_TEXTURE_2D);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
float dw = m_pw / (2 * tileSize);
float dh = m_ph / (2 * tileSize);
int tile_size = tileSize + 1;
GLfloat vertices[(tile_size * tile_size) * 3],
texcoord[(tile_size * tile_size) * 3];
int tindex = -1;
int vindex = -1;
for(int j = 0; j < tile_size; ++j) {
for(int i = 0; i < tile_size; ++i) {
texcoord[++tindex] = m_pw/2 + dw * (i - j);
texcoord[++tindex] = dh * (i + j);
vertices[++vindex] = i;
vertices[++vindex] = j;
vertices[++vindex] = h.get(x + i, y + j);
}
}
GLuint indices[(int)tileSize * tile_size * 4];
int iindex = -1;
for (int i = 0; i < tile_size - 1; ++i) {
for (int j = 0; j < tile_size; ++j) {
indices[++iindex] = j * tile_size + i;
indices[++iindex] = j * tile_size + i + 1;
}
if (++i >= tileSize) { break; }
for (int j = tileSize; j >= 0; --j) {
indices[++iindex] = j * tile_size + i + 1;
indices[++iindex] = j * tile_size + i;
}
}
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glVertexPointer(3, GL_FLOAT, 0, vertices);
glTexCoordPointer(2, GL_FLOAT, 0, texcoord);
glDrawElements(GL_TRIANGLE_STRIP, ++iindex, GL_UNSIGNED_INT, indices);
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glDisable(GL_TEXTURE_2D);
}
