Fusion ShaderBasic Shader
Fusion allows you to combine two textures with a mask using the blending modes standard in photo editing applications, as if they were layers. Using a blend, you can set the opacity of the Blend channel to mix with the Base channel and also modify the mixing with the Mask channel.
Although Fusion shaders can be stacked to allow you to mix more than two textures (by loading Fusion shaders into the Base and Blend channels), we recommend that you use the Layer shader instead in such cases. The Layer shader provides a clearer overview than Fusion when more than two textures are involved in the blend.