Matrix.CreateBillboard centre rotation problem
- by Chris88
I'm having an issue with Matrix.CreateBillboard and a textured Quad where the center axis seems to be positioned incorrectly to the quad object which is rotating around a center point:
Using:
BasicEffect quadEffect;
Drawing the quad shape:
Left = Vector3.Cross(Normal, Up);
Vector3 uppercenter = (Up * height / 2) + origin;
LowerLeft = uppercenter + (Left * width / 2);
LowerRight = uppercenter - (Left * width / 2);
UpperLeft = LowerLeft - (Up * height);
UpperRight = LowerRight - (Up * height);
Where height and width are float values passed in (it draws a square)
Draw method:
quadEffect.View = camera.view;
quadEffect.Projection = camera.projection;
quadEffect.World = Matrix.CreateBillboard(Origin, camera.cameraPosition, Vector3.Up, camera.cameraDirection);
GraphicsDevice.BlendState = BlendState.Additive;
foreach (EffectPass pass in quadEffect.CurrentTechnique.Passes)
{
pass.Apply();
GraphicsDevice.DrawUserIndexedPrimitives
<VertexPositionNormalTexture>(
PrimitiveType.TriangleList,
Vertices, 0, 4,
Indexes, 0, 2);
}
GraphicsDevice.BlendState = BlendState.Opaque;
In the screenshots below i draw the image at Vector3(32f, 0f, 32f)
The screenshots below show you the position of the quad in relation to the red cross. The red cross shows where it should be drawn
http://i.imgur.com/YwRYj.jpg
http://i.imgur.com/ZtoHL.jpg
It rotates around the red cross position
