Access Emissive and other channels trought PP Material?

rohMizuno

Hey, I need to access some channels that are not included on the "SceneTexture" node for a post process material. I am trying to get my material AO, that is there but seems to be disabled, and emissive texture. Does anyone knows of a solution for that?
I found a post on the unreal forum where someone suggest to mess with the shader's code, and make so the specular is always 0,5 no matter what texture you feed him, that way you can plug any texture you want in to the specular and use the "SceneTexture" to access it.
The problem with that solution is 1: I can find that post anymore, lol
2: I am using specular information.

thanks!

edit: the reason I am doing that is that I need to map a global noise texture to my meshes trough post processing, but that texture can not move with the camera, so it need to be mapped to the meshes, the emissive channel is more like example, since maybe if I can access emissive I might be able to access any other map, including custom ones.

rohMizuno

almighty_gir was trying to help me and I realized how bad my explanation is, I basically need this:


But I need to access it trough post processing.

Obscura

Emissive can be filtered out by feeding the hdr scene color into an if. Its more complicated than this but this is a good starting point.

Obscura

For the noise, you can use world position x-y-z and make a manual world aligned noise by using the noise node with optimized settings (fast gradient, 1-2 iterations, and plane projecting it on the 3 axes, then blending them like you would do in a standard world aligned texture function. This should not move with the camera.

Obscura

So I tried this out and actually simply using world position as coordinates in the noise node works fine in a post process:

rohMizuno

that is awesome @Obscura , thanks!
Now the challenge will be get the noise looking the way I want without adding crazy number of instructions. I hope one day they add a custom channel where you can use your own textures.

Obscura

To make the noise showing only on certain surfaces, assign stencils to the object that you want to show the noise, and use them in your post process.

Obscura

rohMizuno said:

that is awesome @Obscura , thanks!
Now the challenge will be get the noise looking the way I want without adding crazy number of instructions. I hope one day they add a custom channel where you can use your own textures.

You could try getting the world aligned texture function to work in a post process. Maybe it does already.

rohMizuno

oh, that does works! I was trying with a triplanar camera vector, but it obviously was moving with the camera
I was assuming that everything created on the PP material would be attached to the camera somehow, that is why I wanted to get the information from the meshes material

rohMizuno

still limited to static objects, but I am using mostly for architecture stuff

Obscura

Not necessarily. You could feed a position from blueprints into your post process that you would just add to the coordinates of the noise of the moving object. This would work on moving but not deforming objects.

rohMizuno

thanks for the help @Obscura , its working great now. Let me ask you, you thing having a world aligned texture being applied to the whole map, except characters, would be to heavy in performance?

poopipe

A post process material will be a fixed cost so you can budget for it easily even if it is expensive.

The downside to doing this in post is that you won't be able to feed the noise back into materials for masking etc. - why is why I've opted to do it in a standard material for my own project.