Shaders: Initialize geometryClearcoatNormal to suppress OpenGL warning.

[c-smile]

Fix of 0(1578) : 'warning C7050: "geometryClearcoatNormal" might be used before being initialized'

Fixed #26994

Description

This warning appears while running ThreeJS on top of WebGL implementation that uses system OpenGL directly.
In particular in Sciter Engine on Windows with OpenGL 4.6 / NVIDIA drivers.

This warning manifests on any attempt to use "physical" materials like:

const material = new THREE.MeshStandardMaterial( { color: 0xFFFFFF } );

Note, no such warning in non-physical materials like MeshNormalMaterial

[github-actions]

📦 Bundle size

Full ESM build, minified and gzipped.

Filesize dev	Filesize PR	Diff
652.2 kB (161.6 kB)	652.3 kB (161.6 kB)	+14 B

🌳 Bundle size after tree-shaking

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

Filesize dev	Filesize PR	Diff
444.9 kB (107.6 kB)	444.9 kB (107.6 kB)	+14 B

[WestLangley]

Initializing a normal to zero raises a red flag: normals are of unit length.

Looking into this, vec3 geometryClearcoatNormal should be declared and initialized inside #ifdef USE_CLEARCOAT.

But you can't do that because of the refactoring in done in #26805.

three.js/src/renderers/shaders/ShaderChunk/lights_fragment_begin.glsl.js

Line 74 in 7bf83b8

RE_Direct( directLight, geometryPosition, geometryNormal, geometryViewDir, geometryClearcoatNormal, material, reflectedLight );

//

Also, CSMShader appears to have the same issue.

[Mugen87]

This initialization is purely technical. As long as the code doesn't use the normal, I see no issue, tbh.

[mrdoob]

@WestLangley Would it be better to initialize it as vec3( 0.0, 0.0, 1.0 )?

[WestLangley]

@mrdoob The real problem is it shouldn't be instantiated at all if it is not going to be used.

[mrdoob]

Ah, so we could do this instead?

#ifdef USE_CLEARCOAT
	vec3 geometryClearcoatNormal = clearcoatNormal;
#endif

[Mugen87]

This does not work which is explained here: #27002 (comment)

[Mugen87]

I have the feeling we overthink this issue a bit. As long as geometryClearcoatNormal isn't used, it's value really does not matter.