Unproject this point from 2D space to 3D space. The point should have its x and y properties set to 2D screen space, and the z either at 0 (near plane) or 1 (far plane). The provided matrix is assumed to already be combined, i.e. projection * view * model.
After this operation, this vector's (x, y, z) components will represent the unprojected 3D coordinate.
Screen x, y, width and height in pixels.
Combined projection and view matrix.