mental ray Architectural and Design Visualization Shader Library

2.5 Detailed Description of Material Parameters 392.5.10 Special MapsThe mia material also supports the following special inputs:2.5.10.1 Bump MappingThe bump parameter accepts a shader that perturbs the normal for bump mapping. Thisparameter is only used it the new bump mode parameter is zero.When no diffuse bump is off, the bumps apply to all shading components (diffuse,highlights, reflections, refractions... ). When it is on, bumps are applied to all componentexcept the diffuse. This means bumps are seen in reflections, highlights, etc. but the diffuseshading shows no bumps. It is as if the materials diffuse surface is smooth, but covered by abumpy lacquer coating.no diffuse bump is off (left) and on (right)In mia material x there are also three new parameters related to bump mapping: twovector bump inputs, overall bump and standard bump, and a bump mode parameterdefining the coordinate-space of those vectors. The shaders put into overall bumporstandard bump should return a vector, but it is also legal for those shaders to modifythe normal vector themselves and return (0,0,0).overall bumpdefines an overall bump that always applies both to the diffuse and the specularcomponent at all times, regardless of the setting of no diffuse bump˙standard bumpis a vector equivalent of the old bump parameter, in that it applies globally whenno diffuse bump is off, and only to the specular/reflection “layer” when no diffuse bumpis on. However, the standard bump is added “on top of” the overall bump result.