Materials store the shader version they were compiled against, added Source( ShaderVersion ) for shaders to query what the current material was compiled against for backwards compatability Blendable: Use hemi octahedron encoded normals same as complex for better quality, remove a redundant texture lookup per layer, remove the 5th unused blend layer because wtf https://files.facepunch.com/matt/1b1811b1/mspaint_qIv6MYpn8Y.png