Improve polygon/convex hull clipping algorithm

[khanghugo]

Works for most cases but the algorithm is pretty messy since it is very original.

Convex hull clipping algorithm is fine. Polygon clipping is not. If anything, convex hull clipping algorithm should be based on that polygon clipping. Right now, they are both different and independent.

[khanghugo]

At the moment, polygon clipping algorithm is copied straight from ChatGPT (with tons of modification of course) but it doesn't quite work

7dd6c56

That is why there is this line

gchimp/src/modules/blender_lightmap_baker_helper.rs

Lines 314 to 316 in 7dd6c56

	// that means chatgpt copy pasted result does not work very good
	// but anyways
	.filter(|polygon| polygon.vertices().len() >= 3)

Convex hull clipping algorithm looks like it works but the current problem is that the new face from result of clipping does not have sorted vertices. In the original algorithm generated by ChatGPT, it does not even account for that face (in another word, the algorithm is bogus along with explanation).