Caching Component

I would love to see a new component, possibly as a piece of Loop components like the accumulator or randomizer, that performs caching.

I have been working with the Loop component to create a hair texture filter by layering individual hair strands, which are manipulated by randomized components, over each other. The first part of this filter uses a chain of components to create a single hair strand, this is then fed into a Loop component where the strand is randomized and layered.

The filter takes quite a while to render, which is expected. In trying to optimize it for better speed, I discovered that if I saved an image of a hair strand and replaced the first portion of the filter with this pre-made image I get a dramatic difference in render time. The version of the filter that creates it's own hair strand takes about 40% longer than the filter that uses the pre-made image.

From reading about how Filter Forge's render engine works, I've come to a conclusion about this render time disparity. Every time the Loop iterates, it re-processes the the hair strand generating portion of the filter even though it is guaranteed to get the same result it did last time. It doesn't realize that none of the per-iteration change components (like randomizer, position, etc) are up-stream of this point.

A simple solution to this problem is to create a caching component. The way this component would work is (potentially) simple: when asked for a pixel, it checks an internal cache to see if that pixel has been supplied before. If it has, it supplies the same result again. If it hasn't, then it goes up-stream and asks the components connected to it for their results, saves the result in the internal cache, and then supplies it.

That's really helpful, thanks!