UV Unwrap freezes exponencially while trying to unwrap a big object

[caioraphael1]

While working on my new PR (#2427 ) for changes to the UV system, I noticed that big objects take longer to Create Texture, or just simply unwrap.

The video below shows 2 identical objects with different sizes, the second one took so long to unwrap that i stopped recording.

2024-07-17.18-49-22.mp4

texture_generator.js / generateFaceTemplate()

The face_group.matrix = getPolygonOccupationMatrix(face_uvs, face_group.width, face_group.height); takes a LOT of time to do, and it's not a big deal to disable it completely in many cases.

blockbench/js/texturing/texture_generator.js

Lines 1174 to 1182 in 813379d

	face_list.forEach(face_group => {
	if (!face_group.mesh) return;
	let face_uvs = face_group.faces.map((face, i) => {
	return face.getSortedVertices().map(vkey => {
	return face_group.vertex_uvs[face_group.keys[i]][vkey];
	})
	});
	face_group.matrix = getPolygonOccupationMatrix(face_uvs, face_group.width, face_group.height);
	})

The real problem tho happens when trying to allocate an empty slot for the faces

blockbench/js/texturing/texture_generator.js

Lines 1241 to 1250 in 813379d

	face_list.forEach(tpl => {
	//Scan for empty spot
	for (var line = 0; line < 2e3; line++) {
	for (var space = 0; space <= line; space++) {
	if (place(tpl, space, line)) return;
	if (space == line) continue;
	if (place(tpl, line, space)) return;
	}
	}
	})

The bigger the area occupied by each face, the more it takes to run through the space.

Disabling Combined Islands also improves a lot the time it takes to unwrap.

Considering all this, I had the idea to do one of the following:

• First, make the projection really small -> Auto UV -> scale to the pixel density.
• Or, improve the code so it can avoid wasting so much time running through so many coordinates.

Tho, I don't know how to make the project small, or how to improve the math so it goes faster for bigger objects.

Model format in which the issue occurs

Generic

Blockbench variant

Program

Blockbench version

4.10.4

Operating System

Win10

Installed Blockbench plugins

No response

[JannisX11]

In 4.11 there will be a progress bar so you can see how long it takes and it doesn't feel like it's stuck. Plus you'll be able to cancel it anytime.