Imagine for example that you're looking at a tutorial to make a procedural wood shader. Without Node Code, to get the completed material you would have to either: Draw the node setup by hand in ...
NODE_SCREEN_TEX, // screen texture sampler (takes UV) (only usable in fragment shader) NODE_SCALAR_OP, // scalar vs scalar op (mul, add, div, etc) NODE_VEC_OP, // vec3 vs vec3 op (mul,ad,div,crossprod ...