procedure sbplnt

This subroutine plots a diffusively-lit, semi-transparent, coloured plane; the use must ensure that all the verticies lie in a flat plane, and that the bounding polygon be convex (so that the angle at any vertex <= 180 degs). All (x,y,z) values are taken to be given in world coordinates. The z-component of the eye-poisition should be positive and that of the vertices should be negative; the viewing-screen is fixed at z=0.

Syntax
sbplnt EYE,NV,VERT,IC1,IC2,LIGHT,ITRANS

Arguments

ARGUMENT    TYPE I/O DIMENSION DESCRIPTION

EYE:   R*4 I 3 (x,y,z) coordinate of eye-position.

NV:   R*4 I - No. of verticies (>=3).

VERT:   R*4 I 3 x NV (x,y,z) coordinate of verticies.

IC1,IC2:   I*4 I - Lowest & highest colour-index to be

   used for the shading.

LIGHT:   R*4 I 3 (x,y,z) direction of flood-light.

ITRANS:   I*4 I - Level of transparency:

   1 = 25%; 2 = 50%; 3 = 75%.

ARGUMENT	TYPE I/O DIMENSION DESCRIPTION
EYE:	R*4 I 3 (x,y,z) coordinate of eye-position.
NV:	R*4 I - No. of verticies (>=3).
VERT:	R*4 I 3 x NV (x,y,z) coordinate of verticies.
IC1,IC2:	I*4 I - Lowest & highest colour-index to be
	used for the shading.
LIGHT:	R*4 I 3 (x,y,z) direction of flood-light.
ITRANS:	I*4 I - Level of transparency:
	1 = 25%; 2 = 50%; 3 = 75%.