graphene:triangle-points (triangle a b c)

triangle -- a graphene:triangle-t instance
a -- a graphene:point3d-t instance for the first vertex
b -- a graphene:point3d-t instance for the second vertex
c -- a graphene:point3d-t instance for the third vertex

The value list of graphene:point3d-t instances with the coordinates of the vertices.

Retrieves the three vertices of the given triangle and returns their coordinates as graphene:point3d-t instances.