genblinds - generate a RADIANCE description of venetian blinds
genblinds mat name depth width height nslats angle [ -r|+r rcurv ]
Genblinds produces a RADIANCE scene description of a set of venetian blinds. The depth of the blinds (X dimension) is given first, followed by the width (Y dimension), followed by the height (Z dimension). The number of slats to place evenly within this height is given as nslats. The angle of the blind, where zero is perfectly horizontal and a positive angle tilts the positive X edge upwards, is given in degrees. The blinds are initially situated so that the corner of the bottom blind is height/nslats/2 above the XY plane, and all coordinates are positive. Each new slat is placed height/nslats above the previous one, until the top slat is at height - height/nslats/2 . The blinds may of course be moved from this starting point with the xform(1) command.
If curved blinds are desired, a radius of curvature may be given with the +/-r option. If given as +r, the curvature is upward, which is the usual configuration. If the option is given as -r, then the curvature is downward. The radius indicates how far from each slat its effective cylindrical center resides. Each slat will be broken into as many polygons as is necessary to keep the delta changes in angle less than 3 degrees. (Note that this may result in a rather large number of polygons.)
To produce a curved set of blinds with 25 slats at 15 degrees:
genblinds white blind 1 46 88 25 15 -r 1 > blinds.rad
Jean-Louis Scartezzini and Greg Ward
genbox(1), genrev(1), gensurf(1), genworm(1), rpict(1), rvu(1), xform(1)