public void setUV(float u0, float v0,
                    float u1, float v1,
                    float u2, float v2) {
    // sets & scales uv texture coordinates to center of the pixel
    u_array[0] = (u0 * F_TEX_WIDTH + 0.5f) * 65536f;
    u_array[1] = (u1 * F_TEX_WIDTH + 0.5f) * 65536f;
    u_array[2] = (u2 * F_TEX_WIDTH + 0.5f) * 65536f;
    v_array[0] = (v0 * F_TEX_HEIGHT + 0.5f) * 65536f;
    v_array[1] = (v1 * F_TEX_HEIGHT + 0.5f) * 65536f;
    v_array[2] = (v2 * F_TEX_HEIGHT + 0.5f) * 65536f;
  }