How do you create an off-center PerspectiveCamera in WPF?

问题

I'm trying to more or less recreate Johnny Lee's Wii head tracking app, but using an augmented reality toolkit for the tracking, and WPF for graphics. To do this, I need to create a perspective camera using the top, bottom, right, and left parameters to create my viewing frustum, instead of field of view and aspect ratio (to those familiar with OpenGL, I want to use the WPF equivalent of glFrustum instead of gluPerspective)

The problem is, those options don't seem to be available on WPF's PerspectiveCamera class. I could probably create the projection matrix manually if I had to and use MatrixCamera, but I'd like to avoid that. Does anyone know of a better way to do this?

回答1:

I never did find a built-in way to do this, so I wrote my own. The math behind it can be found in the OpenGL glFrustum docs. If anyone else ever runs into this problem, this should work for you:

public Matrix3D CreateFrustumMatrix(double left, double right, double bottom, double top, double near, double far)
{
    var a = (right + left) / (right - left);
    var b = (top + bottom) / (top - bottom);
    var c = -(far + near) / (far - near);
    var d = -2 * far * near / (far - near);

    return new Matrix3D(
        2 * near / (right - left), 0,                         0, 0,
        0,                         2 * near / (top - bottom), 0, 0,
        a,                         b,                         c, -1,
        0,                         0,                         d, 0);
}

Just set MatrixCamera.ProjectionMatrix to the return value of that method, and you're all set.

来源：https://stackoverflow.com/questions/1308395/how-do-you-create-an-off-center-perspectivecamera-in-wpf