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# Plot a 3D function
catch { load ./gifplot[info sharedlibextension] gifplot}
# Here is the function to plot
proc func { x y } {
return [expr { 5*cos(2*sqrt($x*$x+$y*$y))*exp(-0.3*sqrt($x*$x+$y*$y)) }]
}
# Here are some plotting parameters
set xmin -5.0
set xmax 5.0
set ymin -5.0
set ymax 5.0
set zmin -5.0
set zmax 5.0
# Grid resolution
set nxpoints 60
set nypoints 60
set cmap [new_ColorMap cmap]
set frame [new_FrameBuffer 500 500]
FrameBuffer_clear $frame $BLACK
set p3 [new_Plot3D $frame $xmin $ymin $zmin $xmax $ymax $zmax ]
Plot3D_lookat $p3 [expr {2*($zmax-$zmin)}]
Plot3D_autoperspective $p3 40
Plot3D_rotu $p3 60
Plot3D_rotr $p3 30
Plot3D_rotd $p3 10
proc drawsolid { } {
global xmin ymin zmin xmax ymax zmax nxpoints nypoints p3 BLACK
Plot3D_clear $p3 $BLACK
Plot3D_start $p3
set dx [expr {1.0*($xmax-$xmin)/$nxpoints}]
set dy [expr {1.0*($ymax-$ymin)/$nypoints}]
set cscale [expr {240.0/($zmax-$zmin)}]
set x $xmin
for {set i 0} {$i < $nxpoints} {incr i 1} {
set y $ymin
for {set j 0} {$j < $nypoints} {incr j 1} {
set z1 [func $x $y]
set z2 [func [expr {$x+$dx}] $y]
set z3 [func [expr {$x+$dx}] [expr {$y+$dy}]]
set z4 [func $x [expr {$y+$dy}]]
set c1 [expr {$cscale*($z1-$zmin)}]
set c2 [expr {$cscale*($z2-$zmin)}]
set c3 [expr {$cscale*($z3-$zmin)}]
set c4 [expr {$cscale*($z4-$zmin)}]
set c [expr {int(($c1+$c2+$c3+$c4)/4)}]
if {$c < 0} { set c 0 }
if {$c > 239} { set c 239 }
Plot3D_solidquad $p3 $x $y $z1 [expr {$x+$dx}] $y $z2 [expr {$x+$dx}] [expr {$y+$dy}] $z3 $x [expr {$y+$dy}] $z4 [expr {$c+16}]
set y [expr {$y + $dy}]
}
set x [expr {$x + $dx}]
}
}
puts "Making a nice 3D plot..."
drawsolid
FrameBuffer_writeGIF $frame $cmap "image.gif"
puts "Wrote image.gif"
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