The “Snow” texture varies the surface color based on the orientation of the surface. With the default settings, the snow color will appear on the top of the object and the surface color will appear on the bottom. The rate at which the snow color blends into the surface color is determined by the “depth_decay” parameter. The threshold determines the maximum slope that will hold snow. (Thicker snow is more opaque). The direction of the snow (determined by wind in the real world) may be set by rotating the texture placement icon, or in sdl by setting the “vector” parameter.
Fractal bump maps are useful in combination with snow because the snow follows the bumping. This creates realistic snow effects by simulating the clumping of snowflakes. Generally, the alpha mult and blur mult for the fractal bump map should be low for best results.
It is useful also to make snow a transparency map on a white shader that is then layered on other shaders in a scene. In this manner the snow can be applied to all the objects in a scene. This also allows the snow to have its own unique shading attributes. Note that the alpha mult should be -1.0 and the alpha offset should be 1.0 for the snow transparency map.
| Argument Name | Absolute Range | Useful Range | Default | Description |
| snow_color | 0, infinity | 0,255 | 255,255,255 | Color of snow |
| surface_color; | 0, infinity | 0,255 | 128, 0, 0 | Color of surface |
| contrast | 0, 1 | 0, 1 | 1.0 | Contrast between surface and snow color |
| threshold | 0, 1 | 0, 1 | 0.5 | Max slope for snow |
| depth_decay | 0, infinity | 0, 10 | 5.0 | Rate of transition between snow and surface color |
| thickness | 0, 1 | 0, 1 | 1.0 | This determines the opacity of the snow |
| vector_x | -infinity, infinity | -1, 1 | 0.0 | up vector for snow |
| vector_y | -infinity, infinity | -1, 1 | 1.0 | |
| vector_z | -infinity, infinity | -1, 1 | 0.0 | |
| transformation_name | no default. |
