Ok sorry i was thinking you could invert the forward to fix that well.
Does it mean it’s normal that the result show the back of the quad?
Normally id say no in fact im not sure why the function is negating the forward direction honestly i would do this myself with create world. Either way it’s sort of trivial for a billboard since you want the quads rotation locked to the cameras backwards then again the CreateLookAt swaps the forward as well.
I wouldn’t worry too much about the texture being off though just flip the u or v or both.
Just keep a seperate quad for this specifically.
I build a quad just for billboarding and then adjust the uv’s (u,v) as needed.
If you want to flip a texure horizontally or vertically…
just flip the whole columns x or y from 0 to 1 or 1 to 0.
for example. To flip this around so its upside down.
change this (u,v)
quadVertices[0].TextureCoordinate = new Vector2(0, 1);
quadVertices[1].TextureCoordinate = new Vector2(0, 0);
quadVertices[2].TextureCoordinate = new Vector2(1, 1);
quadVertices[3].TextureCoordinate = new Vector2(1, 0);
to this
quadVertices[0].TextureCoordinate = new Vector2(0, 0);
quadVertices[1].TextureCoordinate = new Vector2(0, 1);
quadVertices[2].TextureCoordinate = new Vector2(1, 0);
quadVertices[3].TextureCoordinate = new Vector2(1, 1);
if you had instead wanted to flip it so its left was its right.
change this (u,v)
quadVertices[0].TextureCoordinate = new Vector2(0, 1);
quadVertices[1].TextureCoordinate = new Vector2(0, 0);
quadVertices[2].TextureCoordinate = new Vector2(1, 1);
quadVertices[3].TextureCoordinate = new Vector2(1, 0);
to this.
quadVertices[0].TextureCoordinate = new Vector2(1, 1);
quadVertices[1].TextureCoordinate = new Vector2(1, 0);
quadVertices[2].TextureCoordinate = new Vector2(0, 1);
quadVertices[3].TextureCoordinate = new Vector2(0, 0);
The Matrix.CreateBillboard is like CreateWorld in that it gives you a world matrix but like CreateLookAt.
When the camera rotates or moves around in your world, you need to update these billboards.
It just takes a bit of practice.