Here’s the coded formula to obtain pixel perfect sprites by moving the camera in the Z axis just before rendering:

// camera is the current Camera3D object with a PerspectiveLens
// h has to be the height of your current viewport
var h:Number = /*current viewport*/stage3DProxy.viewPort.height;
var fovy:Number = (camera.lens as PerspectiveLens).fieldOfView*Math.PI/180;
camera.z = -(h/2) / Math.tan(fovy/2);

…just a snippet, hope you find it useful

More on this topic:
- http://knol.google.com/k/perspective-transformation
- http://en.wikipedia.org/wiki/3D_projection

I highly suggest to take a look to those interviews, just to be aware of what’s going on

here’s the links:

• http://dailypv3d.wordpress.com/2008/05/22/interview-with-ralph-hauwert/
• http://www.dreaminginflash.com/2008/05/21/interview-with-rob-bateman-away3d/

..and here’s the little summary:

1. Features such as native 3D APIs won’t affect both engines because they’re based on drawing triangles (skewing)
2. Otherwise, new drawing APIs will strongly improve both engines performances, vectors of drawTriangle instruction will replace arrays of very long drawing instructions
3. PixelBender will enhace shaders’ performances, Ralph talks about 10 times faster… Both are quite sure this technology will be used on shaders.
4. Both are assuming it would be great (but not a priority) to implement vector render (as Five3D already does)

stay tuned,

byez