this is about shaders, which have no persistent memory even pixel-to-pixel on the same frame. there is no way to accumulate over time. and calculating outside o

this is about shaders, which have no persistent memory even pixel-to-pixel on the same frame. there is no way to accumulate over time. and calculating outside of the shader would miss the point. so you're stuck doing it from scratch every pixel. that's fine, shaders are fast. at most it might make sense to calculate a truncated time globally per frame and provide that as a uniform.