Access Blend Weight in custom Post Processing Material

Development World Creation
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1

Hello,

I’ve got a quick question about Post Processing Materials.
How would I access the Blend Weight from within my material (I have tried just adding a parameter named “BlendWeight” but with no result).

Right now I don’t get a smooth transition when I enter the Post Processing Volume (I do if I only use the default effects and not my own custom one).

Thank you!

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I still haven’t been able to find a solution to this. Anyone?

3

Hello Spiderhund,

The option you are looking for is the Blend Radius. This takes the distance in Unreal units around the volume at which blending with the volume’s settings occurs. Hope this answers your question.

Here is some more helpful documentation on Post Processing Volume and how they work:

4

That answer needs clarification. Do you mean create a single float parameter and name it “Blend Radius” to gain access to the blend weight value as your camera moves into and out of the volume.

I tried that and it doesn’t work. My custom postprocessing materials are acting binary at the moment. They turn on 100% the moment I enter the edge of the blend radius on my volume. I’m searching for a way to smooth it out. I even went digging through the source code. In the source code it appears to be trying to take every parameter and scale it down to 0 via the blend weight.

Any further advice on this topic would be wonderful.

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Hi. I have similar problem. Any solution?

6

Here’s the solution! (I know this is an old thread, but I wanted to get the answer up for people who need it. Works in UE5 too.)

  1. In your PostProcess material, create a parameter called BlendWeight. (Has to be exactly that, including capitalization.)
  2. Set BlendWeight’s default value to 0.
  3. Create a material instance of your PostProcess material.
  4. In this material instance, set BlendWeight to 1.
  5. Hook the material instance up to your PostProcess volume instead of the master material.

This will allow your custom material to fade on and off smoothly as you move in and out of the PostProcess volume. (If it still doesn’t behave correctly, the culprit could be the PostProcessVolume actor’s settings or the node network in the material itself.)

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