gerard@CGL.UCSF.EDU (09/21/88)
> {allegra,philabs,cmcl2,rutgers}!phri!roy -or- phri!roy@uunet.uu.net > I still maintain that NeWS is different enough from PostScript to > make in inadvisable to use the former as a tool for learning the latter. Roy, Curt.McDowell (cm26+@andrew.cmu.edu) has recently posted (in comp.graphics) an interesting 3-D pyramid fractal, written in PostScript. You can adjust the viewing angle by modifying alpha and beta parameters. Unfortunately, sending the program to a laser printer is not very fast. You can also view it with psview, but it is also slow. However, by modifying SLIGHTLY Curt's program, to run it under NeWS, You get a much faster response time, and you can learn some PostScript tips (I did !). Nota bene, The program below has been written by Curt McDowell, I just made some small modifications to run it with NeWS. (More than 3/4 is `pure' PostScript less than 1/4 is NeWS !). ___________________________________________________________________________ #! /usr/NeWS/bin/psh % | Z % alpha -> Rotation around the Z axis | % (front corner moving left) |_________ X % beta -> Rotation around the Y / % (top corner moving away) / % / Y /alpha -11 def /beta -10 def /shadeleft 1 def /shaderight 0.1 def /pagew 300 def /pageh 400 def /StartSize 1.6 def /MinSize 0.2 def /sina alpha sin def /sinb beta sin def /cosa alpha cos def /cosb beta cos def % Transformation from 3-D coordinates to 2-D /xform % alpha,beta,x,y,z ==> x',y' { /zz exch def /yy exch def /xx exch def /Beta exch def /Alpha exch def yy Alpha cos mul xx Alpha sin mul sub pagew 2 div mul % Compute X and pagew 2 div add % leave on stack xx Beta sin mul Alpha cos mul yy Alpha sin mul Beta sin mul add zz Beta cos mul add pageh 2 div mul % Compute Y and pageh 2 div add % leave on stack } def % Constants /sqr3o4 3 sqrt 4 div def /sqr3o2 3 sqrt 2 div def /sqr3o6 3 sqrt 6 div def /sqr6o3 6 sqrt 3 div def /sqr3o12 3 sqrt 12 div def /sqr6o6 6 sqrt 6 div def /pyramid % alpha,beta,x,y,z,size ==> -- { gsave /size exch def /z exch def /y exch def /x exch def /beta exch def /alpha exch def % (ax, ay) = Left bottom point alpha beta x y z xform /ay exch def /ax exch def % (bx, by) = bottom front point alpha beta sqr3o2 size mul x add size 2 div y add z xform /by exch def /bx exch def % (cx, cy) = Right bottom point alpha beta x size y add z xform /cy exch def /cx exch def % (dx, dy) = top point alpha beta sqr3o6 size mul x add size 2 div y add sqr6o3 size mul z add xform /dy exch def /dx exch def % Fill the 2 visible faces with different shades ax ay moveto bx by lineto dx dy lineto closepath shadeleft setgray fill cx cy moveto bx by lineto dx dy lineto closepath shaderight setgray fill % Draw the 5 visible segments 0 setgray 0.1 72 div setlinewidth ax ay moveto bx by lineto cx cy lineto dx dy lineto closepath dx dy moveto bx by lineto stroke grestore } def % Recursive routine to build a pyramid out of subpyramids /buildsave { alpha beta x y z size } def /buildrest { /size exch def /z exch def /y exch def /x exch def /beta exch def /alpha exch def } def /build { % alpha,beta,x,y,z,size ==> -- /size exch def /z exch def /y exch def /x exch def /beta exch def /alpha exch def size MinSize lt { buildsave alpha beta x y z size pyramid buildrest } { buildsave alpha beta x y z size 2 div build buildrest buildsave alpha beta x size 2 div y add z size 2 div build buildrest buildsave alpha beta sqr3o12 size mul x add size 4 div y add sqr6o6 size mul z add size 2 div build buildrest alpha beta sqr3o4 size mul x add size 4 div y add z size 2 div build } ifelse } def /go { Zrot Yrot 0 StartSize -2 div StartSize sqr6o6 mul -2 div StartSize build } def /main { /Zrot 1 def /Yrot 1 def /Zrotchoice [(-180)(-120)(-90)(-20)(-10)(0)(10)(20)(30)] [{ /Zrot currentkey cvi store /paint win send}] /new DefaultMenu send def /Yrotchoice [(-180)(-120)(-100)(-80)(-60)(-50) (-30)(-20)(-10)(0)(10)(20)(30)] [{ /Yrot currentkey cvi store /paint win send}] /new DefaultMenu send def /setstartsize [(0.5)(1.0)(1.5)(2)(2.5)(3.0)] [{ /StartSize currentkey cvr store /paint win send}] /new DefaultMenu send def /setminsize [(0.2)(0.5)(1.0)(1.5)] [{ /MinSize currentkey cvr store /paint win send}] /new DefaultMenu send def /win framebuffer /new DefaultWindow send def { /PaintClient { gsave alpha go grestore } def /FrameLabel (Receptor) def /PaintIcon {} def /ClientMenu [ (Z Rotation =>) Zrotchoice (Y Rotation =>) Yrotchoice (StartSize =>) setstartsize (MinSize =>) setminsize ] /new DefaultMenu send def } win send 500 600 400 600 /reshape win send /map win send } def main