Light Shader Inputs?

[Kolupsy]

It seems that you cant add any new properties to a light shader and light shaders are not exposed in the render graph to pass in textures too. I want to be able to send a texture to a light texture. Also i noticed that MODEL is not defined in a Light shader. Maybe that would be a good idea to be able to get a lights matrix, position, rotation and scale ect.

[pragma37]

It seems that you cant add any new properties to a light shader and light shaders are not exposed in the render graph to pass in textures too.

Sorry, I don't get what this means.

Also i noticed that MODEL is not defined in a Light shader. Maybe that would be a good idea to be able to get a lights matrix, position, rotation and scale etc.

The actual object matrix is not currently sent to Malt, but yep, that would be nice to add.
We may want to tweak the input nodes based on shader type too.

[Kolupsy]

Sorry, I don't get what this means.

Sorry I meant to attach an image...
This one:

We may want to tweak the input nodes based on shader type too.

That would probably be necessary yeah

[pragma37]

This one:

🤔
Could you give me an example use case?

[Kolupsy]

Could you give me an example use case?

I would love to. I generated an image texture in the pipeline and would like to feed it into the light shader to sample.
My concrete example is an animated cloud texture. I generate it using the noise function, write it to a texture, do some kuwahara filtering on it to make it more stylized and then pass it to both the world material pass as well as the sun light shader (to fake clouds shadows using the Gobo approach (https://en.wikipedia.org/wiki/Gobo_(lighting))

[Kolupsy]

But, for now, I think the best solution would be to just wrap it inside a plugin.

That would definitely be enough for me for now.

The thing is custom inputs would be shared for all lights

That already is the case for custom inputs for the Mesh MAIN PASS and PRE PASS too though right? They also all share the custom inputs.

What do I need to do to go ahead with your proposed solution?

[pragma37]

Oops! I forgot to answer this.

So the basic idea is that the plugin adds something like this to your shader library:

uniform sampler2D MY_CLOUD_TEXTURE;

vec4 get_cloud_texture(vec2 uv)
{
    return texture(MY_CLOUD_TEXTURE, uv);
}

And then, on a render node (before the Pre Pass node), you do something like this:

from Malt.Scene import TextureShaderResource
inputs['Scene'].shader_resources["MY_CLOUD_TEXTURE"] = TextureShaderResource('MY_CLOUD_TEXTURE', t_cloud_texture)

Here, t_cloud_texture would be a Malt Texture object. You would have to take the Scene as input AND output (so the node is part of the graph).

A global resource system would be essentially the same with a UI on top.
So you have a render node that adds shader resources to the scene and a shader node that generates the uniform declarations and retrieves them.

[Kolupsy]

couldnt you abstract the node that would have the second code example to have a node that generally saves textures as shader resources and for the first example you could just use the inline code node to get the texture inside the light shader (or any shader I assume)?

[pragma37]

That's more or less what I meant in my last paragraph.
Except you can't simply use an inline node on the shader side since you have to declare the uniform in the global scope.

A global resource system could be useful for other types of variables too, not just textures.

[Kolupsy]

oh right I forgot about that first line in the first code example hehe