Problem with sprites

[Boothand]

I've been trying to do this for many hours... I'm quite close, but something really weird is going on.

 

I have a chains.tga I've made myself, and want to use it as a sprite (autosprite2).

 

Here is the shader:

 

textures/Bootland/chains
{
	qer_editorimage textures/Bootland/chains.tga
	deformVertexes autosprite2
	q3map_onlyvertexlighting
	q3map_nolightmap
	{
	map textures/Bootland/chains
	blendFunc GL_SRC_ALPHA GL_ONE_MINUS_SRC_ALPHA
	alphaFunc GT0
	depthWrite
	rgbGen identity
	}
}

Problem: The sprite's texture twists and breaks off in a way, if I'm using a simple patch mesh (in-game).

 

Here are some pictures to show what happens.

 

 

In this picture, you see the chain to the left, a patch mesh. To the right is a sprite on an ordinary square brush. It has nodraw on the other sides but the front. This sprite doesn't follow the camera 360 degrees around, but stops after 180. The patch mesh follows all the way, but remains bugged.

https://dl.dropboxusercontent.com/u/58757568/sprite1.jpg

 

Here is a big match mesh with the same sprite, just in case it makes it clearer.

That's supposed to be straight, and whole.

https://dl.dropboxusercontent.com/u/58757568/sprite2.jpg