Specular shader chunk

Hello, i want to apply more than one metalic map to a material.
So i can have multiple stripes of “metal” in a model. And also remove them individually.

I added color stripes editing this chunk.

But i cant do the same for this chunk https://github.com/playcanvas/engine/blob/master/src/graphics/program-lib/chunks/metalness.frag

I believe my problem is i dont know what to override.
In the diffuse was this.material.chunks.diffusePS = this.shader_diffuseConstPS.resource.
Of course if a override the diffusePS with a specular gives an error. But i tried specularPS and other variations and it gets ignored.

Clearly i am really ignorant in this topic. But i dont know where to look for more info.


Pardon my ignorance on your project, but wouldn’t it be a bit easier to just have one material with a varying metalness and specular map to fake two or more different metals?

For sure that sounds easier, but how you assign one material with more than one metalness?

Sorry for late response.
This tutorial might help…switching textures at runtime:

Runtime Texture update

I wanted the ability of having more than one metallness texture map.
Finally i used another method.
Still would like to have some example of expanding the specular shader chunk. If someone knows how to do it.

This is a simplified version, but why couldn’t you just vary the grayscale values of each different metal, within the metalness map…like so:

Perhaps it is metalnessPS? I’m inferring that from the references below which are a bit over my head.

and here: