5.1.6 Prism

The syntax of the prism object is:

PRISM:
  prism { [PRISM_SPLINE_TYPE] [PRISM_SWEEP_TYPE] 
		HEIGHT0, HEIGHT1, NUM_POINTS, POINT_LIST [open] [PRISM_MODIFIERS] }
  
PRISM_SPLINE_TYPE:
  linear_spline | quadratic_spline | cubic_spline | bezier_spline

PRISM_SWEEP_TYPE:
  linear_sweep | conic_sweep

PRISM_MODIFIERS:
  [sturm [BOOL]] | [OBJECT_MODIFIERS]

See also:

• [pov:6.5.1.8]Prism
• [pov:3.4.3]Prism Object
• www.f-lohmueller.de/.../prism1e.htm

This describes a pyramid whose base is given by NUM_POINTS many 2d-points listed in POINT_LIST and it extends in $y$-direction from height HEIGHT0 to HEIGHT1.

Figure: Prismas

The type PRISM_SPLINE_TYPE determines how the points are connected by splines (see (5.1.7)) and the keyword conic_sweep instead of linear_sweep for the PRISM_SWEEP_TYPE makes a pyramid with base at $Y=1$ and vertex at 0.

Figure: Pyramids