procedure sbball

This subroutine plots a shiny or matt coloured ball. 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 ball-centre should be negative (< -radius); the viewing-screen is fixed at z=0.

Syntax
sbball EYE,CENTRE,RADIUS,IC1,IC2,LIGHT,LSHINE,X0,Y0,R0

Arguments

ARGUMENT    TYPE I/O DIMENSION DESCRIPTION

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

CENTRE:   R*4 I 3 (x,y,z) coordinate of ball-centre.

RADIUS:   R*4 I - Radius of ball.

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

   used for shading.

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

LSHINE:   L*1 I - Shiny ball if .TRUE., else diffuse.

X0,Y0:   R*4 O - Centre of projected ball.

R0:   R*4 O - Average radius of projected ball.

ARGUMENT	TYPE I/O DIMENSION DESCRIPTION
EYE:	R*4 I 3 (x,y,z) coordinate of eye-position.
CENTRE:	R*4 I 3 (x,y,z) coordinate of ball-centre.
RADIUS:	R*4 I - Radius of ball.
IC1,IC2:	I*4 I - Lowest & highest colour-index to be
	used for shading.
LIGHT:	R*4 I 3 (x,y,z) direction of flood-light.
LSHINE:	L*1 I - Shiny ball if .TRUE., else diffuse.
X0,Y0:	R*4 O - Centre of projected ball.
R0:	R*4 O - Average radius of projected ball.