Mouse drag: orbit the camera.
Shift + mouse drag: pan the camera.
Ctrl + mouse drag: dolly the camera.
Notice that polygons near the contour (oriented at nearly a glancing angle) are sometimes incorrectly rendered as either frontfaces or backfaces. This happens for two reasons. First, the mesh is made of quadrilaterals that are *not* planar, which causes some error in the computation to determine which faces are front- or back-facing. Second, the computation to determine which faces are front- or back-facing assumes that a perspective projection is used. If the perspective projection is turned off, this increases the number of misclassified polygons close to the contour.
Equation for sea shell: http://xahlee.info/SpecialPlaneCurves_dir/Seashell_dir/