;;; Plot a 3D function ;; Use the wrapped GIFPlot library (use-modules (gifplot)) ;; Here is the function to plot (define (func x y) (* 5 (cos (* 2 (sqrt (+ (* x x) (* y y))))) (exp (* -0.3 (sqrt (+ (* x x) (* y y))))))) ;; Here are some plotting parameters (define xmin -5.0) (define xmax 5.0) (define ymin -5.0) (define ymax 5.0) (define zmin -5.0) (define zmax 5.0) ;; Grid resolution (define nxpoints 60) (define nypoints 60) (define cmap (new-ColorMap "cmap")) (define frame (new-FrameBuffer 500 500)) (FrameBuffer-clear frame (BLACK)) (define p3 (new-Plot3D frame xmin ymin zmin xmax ymax zmax)) (Plot3D-lookat p3 (* 2 (- zmax zmin))) (Plot3D-autoperspective p3 40) (Plot3D-rotu p3 60) (Plot3D-rotr p3 30) (Plot3D-rotd p3 10) (define (drawsolid) (Plot3D-clear p3 (BLACK)) (Plot3D-start p3) (let ((dx (/ (- xmax xmin) nxpoints)) (dy (/ (- ymax ymin) nypoints)) (cscale (/ 240 (- zmax zmin)))) (let x-loop ((x xmin) (i 0)) (cond ((< i nxpoints) (let y-loop ((y ymin) (j 0)) (cond ((< j nypoints) (let* ((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))) (cc (/ (+ c1 c2 c3 c4) 4)) (c (round (max (min cc 239) 0)))) (Plot3D-solidquad p3 x y z1 (+ x dx) y z2 (+ x dx) (+ y dy) z3 x (+ y dy) z4 (+ c 16))) (y-loop (+ y dy) (+ j 1))))) (x-loop (+ x dx) (+ i 1))))))) (display "Making a nice 3D plot...\n") (drawsolid) (FrameBuffer-writeGIF frame cmap "image.gif") (display "Wrote image.gif\n")