"add to current state" feature and other requests

[savat]

Hi, I'm wondering if could be possible avoid to lost already caluclated geometry and/or light samples in some cases:
- light samples if I've to increase/decrease the image size;
- new geometry if I've to add "little things" to a massive scene.

Another think about the "gray material" button...why not a clean slot material so we can start to create some comp layers like AO, z-depht and so on?

Last for now....a better direct light kernel approach (just like a lc+lc in vray) so we can switch from low to medium quality previsualization.

[Karba]

FStorm doesn't have any precalculated light samples.
Acceleration structure must be recalculated from scratch even in case of small changes.

I will implement layers/elements/passes in the future.

FStorm is unbiased render. No light cash for now.