Exploring 3D space with a computer - Part 2: a set of solids
Adrian Oldknow
The Rotation Tool
We have already met the `Translation' tool - which uses a vector to specify the translation. The final tool in the Transformation toolbox is `Rotation'. This is specified by an axis to rotate about and the positions of two points to specify the angle to turn through.
Points A and B lie in the ground plane. The perpendicular to the plane through A is taken, together with B , to define a circle in the plane. The point C is taken anywhere on the circle, and radii AB, AC are drawn. The pyramid WXYZ is transformed by rotating each of its triangular faces in turn around the perpendicular line by the angle defined by points B and C .
Use the working model below, or download the file 
Rotation.cg3. See the effect of moving any of the points A,B,C, or the vertices W,X,Y,Z .
