fix(layers): Fix MVTLayer + pickMultipleObjects

[donmccurdy]

The instancePickingColors attribute has some hard-coded assumptions about size, such as...

deck.gl/modules/core/src/lib/layer.ts

Lines 879 to 882 in 27d2010

	attributeManager.addInstanced({
	instancePickingColors: {
	type: 'uint8',
	size: 4,

... but MVTLayer currently initializes the buffer with 3, not 4, components. This leads to a bug in pickMultipleObjects where disablePickingIndex fails to disable the previously selected object index (or goes out of bounds) and the operation just returns depth duplicate references to the top hit.

While we could try to handle multiple attribute sizes, I think it's probably preferable to just have one way to represent things. Here I've switched MVTLayer to 4-component picking colors, following WebGL's 4-byte alignment best practices.

• Fixes [Bug] PickMultipleObjects Returning the Same Objects Repeated With MVT Layer #9228

Change List

• fix(layers): GeoJSONLayer and MVTLayer use 4-component instance picking colors

[donmccurdy]

Changes in this file can be reverted before submitting the PR — they're not required for the fix — but I wanted to highlight one place where the 3 vs 4 component issue came up. Here colors had one size and externalColorAttribute had another, to the indices didn't map correctly.

If we did prefer to support both 3-component and 4-component instance picking colors, though, this isn't enough, there'd be at least 1-2 more places requiring similar fixes.

[Pessimistress]

I feel regardless of how we address it, the fix should go in the Attribute class:

• getVertexOffset should use the "real size"
• there should be an alignment check when size is overridden by an external binary attribute. We moved to 4-component picking color because WebGPU will not support 3-byte colors.

Since these are not required to patch this bug, they should be made against master and the next minor release?

[donmccurdy]

Ok - for now I've reverted the change to layer.ts, so only the change from 3-component to 4-component picking colors is included in the PR.

[coveralls]

coverage: 91.626%. remained the same
when pulling 2f8004b on donmccurdy/fix-mvtlayer-pick-multiple
into 27d2010 on master.