| # Plot a 3D function |
| require 'gifplot' |
| include Gifplot |
| include Math |
| |
| # Here is the function to plot |
| def func(x,y) |
| return 5*cos(2*sqrt(x*x+y*y))*exp(-0.3*sqrt(x*x+y*y)) |
| end |
| |
| # 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) |
| FrameBuffer_clear(frame,BLACK) |
| |
| P3 = new_Plot3D(frame,XMIN,YMIN,ZMIN,XMAX,YMAX,ZMAX) |
| Plot3D_lookat(P3,2*[XMAX-XMIN,YMAX-YMIN,ZMAX-ZMIN].max) |
| Plot3D_autoperspective(P3,40) |
| Plot3D_rotu(P3,60) |
| Plot3D_rotr(P3,30) |
| Plot3D_rotd(P3,10) |
| |
| def drawsolid() |
| Plot3D_clear(P3,BLACK) |
| Plot3D_start(P3) |
| dx = 1.0*(XMAX-XMIN)/NXPOINTS |
| dy = 1.0*(YMAX-YMIN)/NYPOINTS |
| cscale = 240.0/(ZMAX-ZMIN) |
| x = XMIN |
| for i in 0...NXPOINTS |
| y = YMIN |
| for j in 0...NYPOINTS |
| 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 |
| c = 0 if (c < 0) |
| c = 239 if c > 239 |
| Plot3D_solidquad(P3,x,y,z1,x+dx,y,z2,x+dx,y+dy,z3,x,y+dy,z4,c+16) |
| y = y + dy |
| end |
| x = x + dx |
| end |
| end |
| |
| puts "Making a nice 3D plot..." |
| drawsolid() |
| |
| FrameBuffer_writeGIF(frame,cmap,"image.gif") |
| puts "Wrote image.gif" |
