TUD Organische ChemieImmelGraphicsPovray 3.5macro4View or Print this frame onlyView or Print (this frame only)

Example Graphics

(low quality jpg-image only)

Example file (macro4.pov):

// Persistence Of Vision Ray Tracer POV-Ray 3.5 sample Scene
// by Chris Young
// MACRO4.POV demonstrates basic use of a macro as a type
// of procedure that "returns" a value via a parameter but
// only when a lone identifier is passed. If a constant
// or expression is passed, the value cannot be returned.
#include "colors.inc"

light_source { <100,1000,-1000>, White}

camera { location <0,-1,-16> direction 2*z look_at <0,-1,0>}

plane{-z,-10 pigment{checker Cyan,Yellow}}

// Define the macro. Parameters are:
// V: The value to be incremented. New value
// is returned via this parameter so it must be
// a lone identifier. It cannot be a constant or
// an expression.
#macro Inc(V)
#local V=V+1;

#declare Value=5;

text{ttf "timrom.ttf" "#macro Inc(V)",0.1,0 translate 2*y}
text{ttf "timrom.ttf" " #local V=V+1;",0.1,0 translate y}
text{ttf "timrom.ttf" "#end",0.1,0 }

text{ttf "timrom.ttf" concat("#declare Value=",str(Value,0,0),";"),0.1,0 translate -y}

Inc(Value+0) // Expression won't work

text{ttf "timrom.ttf" concat("Inc(Value+0)=",str(Value,0,0)),0.1,0 translate -2*y}

Inc(+Value) // This too is an expression so it won't work

text{ttf "timrom.ttf" concat("Inc(+Value)=",str(Value,0,0)),0.1,0 translate -3*y}

Inc(Value) // Lone identifier works. It accepts return value.

text{ttf "timrom.ttf" concat("Inc(Value)=",str(Value,0,0)),0.1,0 translate -4*y}

translate -3.75*x

© Copyright PD Dr. S. Immel