| Description | Water should not have a hard edge. Most natural water (rivers, sea, sewer) holds small opaque sediment particles and should be opaque after a certain depth, depending on the density of the sediment. Very shallow water should be less noticeable, i.e. you can see through it better.
Create a generic depth_difference shader which paints a grayscale image based on the depth difference between a transparent surface (i.e. water) and the solid background.
This will allow us to represent semi-opaque materials where the opacity depends on the thickness of the material. Sea and river water are obvious examples. We can use the shader with a maskColor command to paint into the alpha layer, then draw the coloured water surface with BLEND BLEND so that the mix of foreground and background texture depends on "how much" of the material is in front of the background.
The opacity should be a shaderparm which determines at what thickness the material becomes opaque, same way that fog distance works. |
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