Multiple issues with scene extents computation

[lexaknyazev]

glTF-Sample-Viewer/source/gltf/gltf_utils.js

Lines 55 to 67 in 831cf2b

	const boxMin = vec3.create();
	let min = jsToGl(accessor.min);
	if (accessor.normalized){
	vec3.normalize(min, min);
	}
	vec3.transformMat4(boxMin, min, worldTransform);
	const boxMax = vec3.create();
	let max = jsToGl(accessor.max);
	if (accessor.normalized){
	vec3.normalize(max, max);
	}
	vec3.transformMat4(boxMax, max, worldTransform);

Incorrect accessor normalization

To get effective min/max values of normalized accessors, their components need to be divided by a constant value determined from the accessor's component type (e.g., 65535 for unsigned short).

Incorrect bounding box transformation

To transform a bounding box, the transformation matrix should be applied to all its eight vertices and then all their components should be compared to determine the new bounding box.

[UX3D-kanzler]

Good catch. Most assets that have normalized and quantized accessors use the complete value range of the component type. For this reason, it is difficult to notice.
I have prepared an asset that does not cover the complete range and hence demonstrates the issue:
Avocado-normalized.zip