Overview
This texture creates a procedural flake normal map that can be used e.g. for car-paint-like materials. It is intended to be used as a normal map inside the bump slot of a material. Note that the map does not perform any filtering, so small flakes require a lot of AA samples to get clean.
The shader code is here: flakes.osl; a sample scene for 3ds Max is here: flakes.zip
Parameters
Outputs
result - the flake normal map color
alpha - a black and white mask for the flakes
Inputs
flake scale - scales the entire flake structure up or down. Larger values zoom out of the map.
flake size - the relative size of the flakes.
flake size variance - determines the randomness of the flake size. 0.0 means all flakes have the specified size.
flake normal orientation - blends between the random flake normal and the smooth surface normal.
Shader code
Here is the shader code:
shader flakes ( float flake_scale = 10.0 [[ string description = "Smaller values zoom into the flake map, larger values zoom out" ]], float flake_size = 0.5 [[ string description = "Relative size of the flakes" ]], float flake_size_variance = 0.0 [[ string description = "0.0 makes all flakes the same size, 1.0 assigns random size between 0 and the given flake size" ]], float flake_normal_orientation = 0.0 [[ string description = "Blend between the flake normals (0.0) and the surface normal (1.0)" ]], output color result = 1.0, output float alpha = 1.0 ) { float safe_flake_size_variance = clamp(flake_size_variance, 0.1, 1.0); vector cellCenters[9] = { vector( 0.5, 0.5, 0.0), vector( 1.5, 0.5, 0.0), vector( 1.5, 1.5, 0.0), vector( 0.5, 1.5, 0.0), vector(-0.5, 1.5, 0.0), vector(-0.5, 0.5, 0.0), vector(-0.5, -0.5, 0.0), vector( 0.5, -0.5, 0.0), vector( 1.5, -0.5, 0.0) }; point position = vector(u, v, 0.0); position = flake_scale * position; point base = floor(position); point nearestCell = point(0.0, 0.0, 1.0); int nearestCellIndex = -1; for(int cellIndex = 0; cellIndex < 9; ++cellIndex) { point cellCenter = base + cellCenters[cellIndex]; vector centerOffset = cellnoise(cellCenter) * 2.0 - 1.0; centerOffset[2] *= safe_flake_size_variance; centerOffset = normalize(centerOffset); cellCenter += 0.5 * centerOffset; float cellDistance = distance(position, cellCenter); if(cellDistance < flake_size && cellCenter[2] < nearestCell[2]) { nearestCell = cellCenter; nearestCellIndex = cellIndex; } } result = color(0.5, 0.5, 1.0); alpha = 0.0; if (nearestCellIndex != -1) { vector randomNormal = cellnoise(base + cellCenters[nearestCellIndex] + vector(0.0, 0.0, 1.5)); randomNormal = 2.0 * randomNormal - 1.0; randomNormal = faceforward(randomNormal, I, randomNormal); randomNormal = normalize(mix(randomNormal, vector(0.0, 0.0, 1.0), flake_normal_orientation)); result = color(0.5*randomNormal[0]+0.5, 0.5*randomNormal[1]+0.5, randomNormal[2]); alpha = 1.0; } }