void UpdateProjectionMatrix(float width, float height)
{
viewportWidth = width;
viewportHeight = height;
double aspect = viewportWidth / viewportHeight;
double nearHeight = camNear * Math.Tan(DMathUtil.DegreesToRadians(camFov / 2));
double nearWidth = nearHeight * aspect;
//float offset = separation / planeDist * near / 2;
frustumWidth = nearWidth;
frustumHeight = nearHeight;
frustumZNear = camNear;
frustumZFar = camFar;
projMatrix = DMatrix.PerspectiveOffCenterRH(-nearWidth / 2, nearWidth / 2, -nearHeight / 2, nearHeight / 2, frustumZNear, frustumZFar);
}
