Simplify breaks due to assertion failed

[wayne-wu]

Simplify breaks due to assertion failed

[donmccurdy]

Ah, well that's a footgun! Should be fixed with:

• #1382

[donmccurdy]

Thanks @wayne-wu! Index count vs. vertex count sounds like a good guess on the cause. Perhaps happening when the source vertex attributes have many vertices, but the indices only use a smaller subset of those. The relevant code is here:

glTF-Transform/packages/functions/src/simplify.ts

Lines 162 to 170 in 3901a3e

	const targetCount = Math.floor((options.ratio * srcVertexCount) / 3) * 3;
	const [dstIndicesArray, error] = simplifier.simplify(
	indicesArray as Uint32Array,
	positionArray as Float32Array,
	3,
	targetCount,
	options.error,
	options.lockBorder ? ['LockBorder'] : [],
	);

I'll look into reproducing the issue without the model, but if you'd like to try making the change and then testing on the model yourself, it would look something like:

yarn install
yarn dist
node packages/cli/bin/cli.js simplify in.glb out.glb

Or yarn watch will continuously watch and rebuild the code as you're making changes.

[donmccurdy]

Fixed and published to 4.0.0-alpha.6. If you'd like to test that fix, you can use the @next tag, like npm install @gltf-transform/cli@next.

[harrycollin]

I encountered this using @gltf-transform/[email protected] package in node.js.

[donmccurdy]

@harrycollin possible to share a reproduction? The tests I have are passing. Meshoptimizer may have assertions for any number of things.

[harrycollin]

My mistake! It looks like I was passing undefined values to the ratio, error and lockBorder options.