| <? |
| |
| # Plot a 3D function |
| include("gifplot.php"); |
| |
| # Here is the function to plot |
| function func($x, $y) { |
| return 5*cos(2*sqrt($x*$x+$y*$y))*exp(-0.3*sqrt($x*$x+$y*$y)); |
| } |
| |
| # Here are some plotting parameters |
| $xmin = -5.0; |
| $xmax = 5.0; |
| $ymin = -5.0; |
| $ymax = 5.0; |
| $zmin = -5.0; |
| $zmax = 5.0; |
| |
| # Grid resolution |
| $nxpoints = 60; |
| $nypoints = 60; |
| |
| $cmap = new ColorMap("cmap"); |
| $frame = new FrameBuffer(500,500); |
| $frame->clear(BLACK); |
| |
| |
| $p3 = new Plot3D($frame,$xmin,$ymin,$zmin,$xmax,$ymax,$zmax); |
| $p3->lookat(2*($zmax-$zmin)); |
| $p3->autoperspective(40); |
| $p3->rotu(60); |
| $p3->rotr(30); |
| $p3->rotd(10); |
| |
| function drawsolid() { |
| global $xmax; |
| global $xmin; |
| global $ymax; |
| global $ymin; |
| global $zmin; |
| global $zmax; |
| global $nxpoints; |
| global $nypoints; |
| global $p3; |
| |
| $p3->clear(BLACK); |
| $p3->start(); |
| $dx = 1.0*($xmax-$xmin)/$nxpoints; |
| $dy = 1.0*($ymax-$ymin)/$nypoints; |
| $cscale = 240.0/($zmax-$zmin); |
| $x = $xmin; |
| for ($i = 0; $i < $nxpoints; $i++) { |
| $y = $ymin; |
| for ($j = 0; $j < $nypoints; $j++) { |
| $z1 = func($x,$y); |
| $z2 = func($x+$dx,$y); |
| $z3 = func($x+$dx,$y+$dy); |
| $z4 = func($x,$y+$dy); |
| $c1 = $cscale*($z1-$zmin); |
| $c2 = $cscale*($z2-$zmin); |
| $c3 = $cscale*($z3-$zmin); |
| $c4 = $cscale*($z4-$zmin); |
| $c = ($c1+$c2+$c3+$c4)/4; |
| if ($c < 0) { $c = 0; } |
| if ($c > 239) { $c = 239; } |
| $p3->solidquad($x,$y,$z1,$x+$dx,$y,$z2,$x+$dx,$y+$dy,$z3,$x,$y+$dy,$z4,$c+16); |
| $y = $y + $dy; |
| } |
| $x = $x + $dx; |
| } |
| } |
| |
| print "Making a nice 3D plot...\n"; |
| drawsolid(); |
| |
| $frame->writeGIF($cmap,"image.gif"); |
| print "Wrote image.gif\n"; |
| |
| ?> |