Editing Fur Shader Passes (section)

== Pass 2 - The Fur ==
Almost nothing is rendered "correctly" by the fur layers. They take every short-cut possible, resulting in all sorts of lighting errors and glitches (if you know what to look for).

However, speed is absolutely essential, because these layers make up the vast majority of the render time, and rendering lots of "cheap" layers looks significantly better than rendering only half as many "expensive" layers.

The shader also has a couple of tricks up its sleeve:

* Trick #1: it can turn the fur layers off (if too far away, offscreen, or backwards) by having the Hull shader ask the Tessellator to multiply the number of triangles by 0, which throws them out before they reach the Geometry shader stage. This is a MASSIVE speed boost, roughly doubling the speed of the shader.

* Trick #2: it can have the Hull shader ask the Tessellator split each triangle into 4 when taking a photo. However, the Domain shader then ignores the Tessellator's instructions, and instead just makes 4 copies of the original, un-tessellated triangle. The fur can thus be rendered at up to 4x resolution, but only when needed.