public static void LegacyProjection(this ICamera camera)
{
if (camera == null) { throw new System.ArgumentNullException("camera"); }
// projection and view matrix.(gluPerspective() and gluLookAt())
mat4 projection = camera.GetProjectionMatrix();
mat4 view = camera.GetViewMatrix();
// Set the projection matrix.(projection and view matrix actually.)
OpenGL.MultMatrixf((projection * view).ToArray());
}
}