/ColorRGB describes current color.
For 3D shapes such as /Box,
it is used as a set of diffusion reflection coefficients.
For polylines, it is regarded as their color directly.
By default, /ColorRGB 1.0 1.0 1.0 is set implicitly.
| Format | /ColorRGB R G B |
| (R, G, B) | red, green, and blue components of color. |
| R, G, B = [0,1] |