GrungeOverlay Material Function
GrungeOverlay is a material function built for the Ascent Robotics Drop Sim. The material function allows dirt and grunge to be added to any material in the drop sim library by simply adding the GrungeOverlay node to the end of the material network. Settings to control the grunge are exposed both in-editor and to the drop sim code. In most cases input parameters for the function will be randomly selected from a min/max range provided via an external parameters.ini file.
Four separate masks are packed into a single RGBA texture for a variety of dirt types.
Each material in the library is condensed down into a set of material attributes. The GrungeOverlay takes this as input and performs its adjustments before outputting the result. Custom view modes remain unaffected by the grunge overlay.
Material parameters are input and adjusted as needed. Special care is taken for metallic materials which can display strange properties when blended with non-metallic grunge overlays.
Strength for each mask is controlled on a 0-1 scale.
Mask levels have been adjusted so that scalar strength values across each mask type return similar dirtiness amounts. The first row is strength 0. The remaining rows show 0.5 and 1.0 values for each mask channel.