Colored Light Functions not work with Blur and Some Functions on 5.5

Development Rendering
1

Hi everyone, how are you?
A while ago I was working on a project that contains a lot of lights. So MegaLights greatly improved the performance of the project. But I noticed that my Light Functions Materials stay in black and white, even though I had the colors activated.

My function material was as simple as a texture sample with a texture coordinate to handle it properly.
But the result was none. The Light only returns white, even though the material “supposedly returns the image or color”.
I removed my Texture Coordinates and it worked fine. But then I had another material that applied a Blur to the image. But this also returns white in this version of Unreal. I’ve been investigating a little, and it seems that there is something strange in the materials that now makes the light functions return nothing.
Is this happening to anyone else?

2

Megalights only supports light functions through the light function atlasing feature, but light functions that mainpulate UV coordinates can’t always be atlas’d. If it can’t be atlas’d, it won’t render with megalights.

This seems to apply to any coordinate manipulation done in the material editor except those output specifically by built-in nodes, excluding material functions… meaning basically panner/rotator will work, but SpiralBlur or even just plugging in texcoord will not… I suspect this limitation is intentional based on the guide, but I’m not entirely sure.

Basically you’re running up against two separate limitations in both systems.

1 Like