I'm not sure if real life soft shadows (from close,large light sources) have a Gaussian or linear falloff, or something else.
I'm working on something where I can create the shadows by manipulating some kind of pre-rendered gradient texture so I am not having to rely on frame buffers and traditional shadowing techniques. I'm planning on baking the gradient into one channel of my mesh's texture and then manipulating the values based on how much shadow covers each quad. This is possible because I just have quads lined up like a zigzag where each peak can cast a shadow onto the next adjacent quad.
So a linear falloff would be easiest (just need to subtract some value from a linear gradient) but I have a hard time telling what actually looks realistic. Is there a simple math formula that could be applied to a linear gradient to pull out a Gaussian approximation?