FunctionNode: Keywords support

[sunag]

Related issue: #23655

Description

const getWGSLTextureSample = new Nodes.FunctionNode( `

	fn getWGSLTextureSample( uv:vec2<f32> ) -> vec4<f32> {

		return textureSample( tex, tex_sampler, uv );

	}

` );

const textureNode = new Nodes.TextureNode( texture );

// set keywords
getWGSLTextureSample.keywords = { tex: textureNode, tex_sampler: sampler( textureNode ) };

This contribution is funded by Google via Igalia.

[LeviPesin]

Couldn't be these keywords be passed just as arguments to the function?
I.e. just something like getWGSLTextureSample.call( { uv: new Nodes.UVNode(), tex: textureNode, tex_sampler: sampler( textureNode ) } ) and getWGSLTextureSample( uv:vec2<f32>, tex: WGSLTextureType, tex_sample: WGSLSamplerType ).

[sunag]

Couldn't be these keywords be passed just as arguments to the function?

Yeah! This was my first approach, but it didn't work, I thought it was a limitation of WGSL, but now I think it is related to NodeMaterial...

[sunag]

Now it worked! 😅

[sunag]

I think that I will keep to support to keywords in NodeMaterial system, while this don't support pointer between function calls... maybe it will be useful for other things too.

[sunag]

Just describing a little more...
This approach below would be the recommended use to call the functions. We also have the option to include the variables via keywords those not passed in arguments is directly replaced in the function code, so that the values can be edited globally since we still don't have inout <-> pointer.

/cc @mrdoob

const getWGSLTextureSample = new Nodes.FunctionNode( `
	fn getWGSLTextureSample( tex: texture_2d<f32>, tex_sampler: sampler, uv:vec2<f32> ) -> vec4<f32> {
		return textureSample( tex, tex_sampler, uv ) * vec4<f32>( 0.0, 1.0, 0.0, 1.0 );
	}
` );

const textureNode = new Nodes.TextureNode( texture );

material = new Nodes.MeshBasicNodeMaterial();
material.colorNode = getWGSLTextureSample.call( { tex: textureNode, tex_sampler: textureNode, uv: new Nodes.UVNode() } );