normalizeViewport
Normalizes the coordinates of a #graphene_point3d_t using the given viewport and clipping planes.
The coordinates of the resulting #graphene_point3d_t will be in the -1, 1 range.
Since
1.4
Parameters
viewport
a #graphene_rect_t representing a viewport
zNear
the coordinate of the near clipping plane, or 0 for the default near clipping plane
zFar
the coordinate of the far clipping plane, or 1 for the default far clipping plane
res
the return location for the normalized #graphene_point3d_t