webgl: Support colorMask in RenderPass

[felixpalmer]

For visgl/deck.gl#8636

When a WebGLRenderPass is created it immediately does a clear(). deck.gl was previously setting a colorMask using withParametersWebGL, but now with this removed there is no way to set the colorMask before the clear operation. Doing it in Pass.getLayerParameters() is too late, as by then the clear operation has happened

Background

Change List

• Support colorMask in RenderPass

[donmccurdy]

Nit: if we require exactly four channel masks, lets make that explicit —

Suggested change

	colorMask?: boolean[];
	colorMask?: [boolean, boolean, boolean, boolean];

[felixpalmer]

Discussing with @Pessimistress we need to think of a way to make this WebGPU compatible. It may make more sense to pass writeMask instead

[donmccurdy]

Hm, there's also the RenderPipeline parameter, colorMask, which is a bit mask:

luma.gl/modules/core/src/adapter/types/parameters.ts

Lines 159 to 160 in f59d1d4

	/** Bitmask controlling which channels are are written to when drawing to this color target. defaulting to 0xF */
	colorMask?: number;

[felixpalmer]

Oh, I missed that! I still think it's worth moving to RenderPassParameters

[Pessimistress]

Defer to @ibgreen - is the WebGPU name writeMask preferred?

[ibgreen]

FWIW

I believe clear colors in WebGPU are set per target (attachment) not as part of the props.

For now, I don't think I exposed that full API.

Why can't we set it before we call gl.clear?

[Pessimistress]

Why can't we set it before we call gl.clear?

We are trying to avoid using setParametersWebGL.

[felixpalmer]

OK, so it seems this change is OK, but we should change it to be a bitmask to align with the WebGPU API before merging