Nodes: Add enableExtension() Method to GLSLNodeBuilder

[cmhhelgeson]

Related issue: #28915

Create a getExtension() function that allows for the conditional application of a GLSL extension when necessary to access a given feature within WebGPURenderer's webgl-fallback.

Example implementation:

enableClipDistances() {

    const extensions = this.renderer.backend.extensions;

    if ( extensions.has( 'WEBGL_clip_cull_distance' ) ) {

        extensions.get( 'WEBGL_clip_cull_distance' );

	this.getExtension( 'GL_ANGLE_clip_cull_distance', 'enable' );

    }

}

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

Filesize dev	Filesize PR	Diff
684 kB (169.4 kB)	684 kB (169.4 kB)	+0 B

🌳 Bundle size after tree-shaking

Minimal build including a renderer, camera, empty scene, and dependencies.

Filesize dev	Filesize PR	Diff
460.9 kB (111.2 kB)	460.9 kB (111.2 kB)	+0 B

[RenaudRohlinger]

This PR breaks the webgpu_mesh_batch example in the WebGL backend.

[cmhhelgeson]

This PR breaks the webgpu_mesh_batch example in the WebGL backend.

Shader stage is being passed in as null for the GL_ANGLE_Multi_Draw extension, which prevents the extension from being written in the vertex stage. I'll push in a fix.