Projects a Cartesian point to screen coordinates, applying an offset to the point's projected depth value. The
resultant screen point is in OpenGL screen coordinates, with the origin in the bottom-left corner and axes that
extend up and to the right from the origin.
This stores the projected point in the result argument, and returns a boolean value indicating whether or not the
projection is successful. This returns false if the Cartesian point is clipped by the near clipping plane or the
far clipping plane.
The depth offset may be any real number and is typically used to move the screenPoint slightly closer to the
user's eye in order to give it visual priority over nearby objects or terrain. An offset of zero has no effect.
An offset less than zero brings the screenPoint closer to the eye, while an offset greater than zero pushes the
projected screen point away from the eye.
Applying a non-zero depth offset has no effect on whether the model point is clipped by this method or by WebGL.
Clipping is performed on the original model point, ignoring the depth offset. The final depth value after
applying the offset is clamped to the range [0,1].