wolffd@0: #
wolffd@0: # data structures
wolffd@0: #
wolffd@0: length = 300;
wolffd@0: center = ['x' = 200; 'y' = 250;];
wolffd@0: radius = 2 * length / sqrt (12);
wolffd@0: fractalangle = 0;
wolffd@0: maxlevel = 2;
wolffd@0: sizes = [
wolffd@0:     'button' = [ 'x' = 100; 'y' = 40;  ];
wolffd@0:     'canvas' = [ 'x' = 400; 'y' = 500; ];
wolffd@0:     'view'   = [ 'x' = 400; 'y' = 600; ];
wolffd@0: ];
wolffd@0: sq = function (x) {
wolffd@0:     return x * x;
wolffd@0: };
wolffd@0: #
wolffd@0: # create view and other widgets
wolffd@0: #
wolffd@0: init = function () {
wolffd@0:     view = createwidget (-1, [
wolffd@0:         'type' = 'view'; 'name' = 'fractal'; 'size' = sizes.view;
wolffd@0:     ]);
wolffd@0: 
wolffd@0:     array1 = createwidget (view, [
wolffd@0:         'type' = 'array'; 'borderwidth' = 1; 'mode' = 'vertical';
wolffd@0:     ]);
wolffd@0:     widgets[array1].resize = resize;
wolffd@0: 
wolffd@0:     array2 = createwidget (array1, [
wolffd@0:         'type' = 'array'; 'borderwidth' = 1; 'mode' = 'horizontal';
wolffd@0:     ]);
wolffd@0:     widgets[array2].resize = resize;
wolffd@0: 
wolffd@0:     array3 = createwidget (array2, [
wolffd@0:         'type' = 'array'; 'borderwidth' = 1; 'mode' = 'vertical';
wolffd@0:     ]);
wolffd@0:     widgets[array3].resize = resize;
wolffd@0: 
wolffd@0:     morebutton = createwidget (array3, [
wolffd@0:         'type' = 'button'; 'text' = 'more';
wolffd@0:     ]);
wolffd@0:     widgets[morebutton].pressed = pressed;
wolffd@0:     lessbutton = createwidget (array3, [
wolffd@0:         'type' = 'button'; 'text' = 'less';
wolffd@0:     ]);
wolffd@0:     widgets[lessbutton].pressed = pressed;
wolffd@0:     setwidgetattr (morebutton, ['size' = sizes.button;]);
wolffd@0:     setwidgetattr (lessbutton, ['size' = sizes.button;]);
wolffd@0: 
wolffd@0:     atext = createwidget (array2, [
wolffd@0:         'type' = 'text'; 'mode' = 'oneline';
wolffd@0:     ]);
wolffd@0:     widgets[atext].oneline = oneline;
wolffd@0:     setwidgetattr (atext, [
wolffd@0:         'size' = ['x' = sizes.button.x; 'y' = sizes.button.y * 2;];
wolffd@0:     ]);
wolffd@0: 
wolffd@0:     scroll = createwidget (array1, ['type' = 'scroll';]);
wolffd@0:     canvas = createwidget (scroll, ['type' = 'canvas';]);
wolffd@0:     wrect = [0 = ['x' = 0; 'y' = 0;]; 1 = sizes.canvas;];
wolffd@0:     setwidgetattr (canvas, ['window' = wrect; 'viewport' = wrect[1];]);
wolffd@0: };
wolffd@0: #
wolffd@0: # drawing functions
wolffd@0: #
wolffd@0: # draw a Koch curve (a ``snowflake'' fractal)
wolffd@0: #
wolffd@0: # start with a triangle and keep replacing edges
wolffd@0: # with the construct: _/\_
wolffd@0: # until the recursion level reaches 'maxlevel'
wolffd@0: #
wolffd@0: fractal = function (level, length, angle) {
wolffd@0:     local nlength, newpenpos;
wolffd@0: 
wolffd@0:     if (level >= maxlevel) {
wolffd@0:         newpenpos.x = penpos.x + length * cos (angle);
wolffd@0:         newpenpos.y = penpos.y + length * sin (angle);
wolffd@0:         line (canvas, null, penpos, newpenpos, ['color' = 1;]);
wolffd@0:         penpos = newpenpos;
wolffd@0:         return;
wolffd@0:     }
wolffd@0:     nlength = length / 3;
wolffd@0:     fractal (level + 1, nlength, angle);
wolffd@0:     fractal (level + 1, nlength, angle + 60);
wolffd@0:     fractal (level + 1, nlength, angle - 60);
wolffd@0:     fractal (level + 1, nlength, angle);
wolffd@0: };
wolffd@0: redrawfractal = function () {
wolffd@0:     clear (canvas);
wolffd@0:     setpick (canvas, center, wrect);
wolffd@0:     penpos = [
wolffd@0:         'x' = center.x + cos (fractalangle + 210) * radius;
wolffd@0:         'y' = center.y + sin (fractalangle + 210) * radius;
wolffd@0:     ];
wolffd@0:     fractal (0, length, fractalangle +  60);
wolffd@0:     fractal (0, length, fractalangle -  60);
wolffd@0:     fractal (0, length, fractalangle - 180);
wolffd@0:     remove ('penpos');
wolffd@0: };
wolffd@0: #
wolffd@0: # editing functions
wolffd@0: #
wolffd@0: # transform the fractal.
wolffd@0: #
wolffd@0: # map point 'prevpoint' to point 'currpoint'
wolffd@0: # with respect to the center of the fractal.
wolffd@0: #
wolffd@0: transformfractal = function (prevpoint, currpoint) {
wolffd@0:     local prevtan, currtan, prevradius, currradius;
wolffd@0: 
wolffd@0:     prevtan = atan (prevpoint.y - center.y, prevpoint.x - center.x);
wolffd@0:     currtan = atan (currpoint.y - center.y, currpoint.x - center.x);
wolffd@0:     fractalangle = fractalangle + (currtan - prevtan);
wolffd@0:     prevradius = sqrt (
wolffd@0:         sq (prevpoint.y - center.y) + sq (prevpoint.x - center.x)
wolffd@0:     );
wolffd@0:     currradius = sqrt (
wolffd@0:         sq (currpoint.y - center.y) + sq (currpoint.x - center.x)
wolffd@0:     );
wolffd@0:     radius = radius / prevradius * currradius;
wolffd@0:     length = radius / 2 * sqrt (12);
wolffd@0: };
wolffd@0: #
wolffd@0: # main actions
wolffd@0: #
wolffd@0: redraw = function (data) {
wolffd@0:     redrawfractal ();
wolffd@0: };
wolffd@0: changemaxlevel = function (dn) {
wolffd@0:     maxlevel = maxlevel + dn;
wolffd@0:     if (maxlevel < 0)
wolffd@0:         maxlevel = 0;
wolffd@0:     redrawfractal ();
wolffd@0: };
wolffd@0: resize = function (data) {
wolffd@0:     local ret;
wolffd@0:     if (data.widget == array1) {
wolffd@0:         ret = [
wolffd@0:             array2 = [
wolffd@0:                 'x' = data.size.x;
wolffd@0:                 'y' = sizes.button.y * 2;
wolffd@0:             ];
wolffd@0:             scroll = [
wolffd@0:                 'x' = data.size.x;
wolffd@0:                 'y' = data.size.y - sizes.button.y * 2;
wolffd@0:             ];
wolffd@0:         ];
wolffd@0:     } else if (data.widget == array2) {
wolffd@0:         ret = [
wolffd@0:             array3 = [
wolffd@0:                 'x' = sizes.button.x;
wolffd@0:                 'y' = 2 * sizes.button.y;
wolffd@0:             ];
wolffd@0:             atext = [
wolffd@0:                 'x' = data.size.x - sizes.button.x;
wolffd@0:                 'y' = 2 * sizes.button.y;
wolffd@0:             ];
wolffd@0:         ];
wolffd@0:     } else if (data.widget == array3) {
wolffd@0:         ret = [
wolffd@0:             morebutton = sizes.button;
wolffd@0:             lessbutton = sizes.button;
wolffd@0:         ];
wolffd@0:     }
wolffd@0:     return ret;
wolffd@0: };
wolffd@0: #
wolffd@0: # user interface functions
wolffd@0: #
wolffd@0: # bind changes to the fractal to user actions
wolffd@0: #
wolffd@0: leftup = function (data) {
wolffd@0:     transformfractal (data.ppos, data.pos);
wolffd@0:     redrawfractal ();
wolffd@0: };
wolffd@0: menu = [
wolffd@0:     0 = 'more';
wolffd@0:     1 = 'less';
wolffd@0: ];
wolffd@0: domenu = function (i) {
wolffd@0:     local s;
wolffd@0:     s = menu[i];
wolffd@0:     if (s == 'more')
wolffd@0:         changemaxlevel (1);
wolffd@0:     else if (s == 'less')
wolffd@0:         changemaxlevel (-1);
wolffd@0: };
wolffd@0: rightdown = function (data) {
wolffd@0:     domenu (displaymenu (canvas, menu));
wolffd@0: };
wolffd@0: pressed = function (data) {
wolffd@0:     if (data.widget == morebutton)
wolffd@0:         changemaxlevel (1);
wolffd@0:     else if (data.widget == lessbutton)
wolffd@0:         changemaxlevel (-1);
wolffd@0: };
wolffd@0: oneline = function (data) {
wolffd@0:     local dn;
wolffd@0:     dn = ston (data.text);
wolffd@0:     if (dn > 0 | dn < 0)
wolffd@0:         changemaxlevel (dn - maxlevel);
wolffd@0: };
wolffd@0: #
wolffd@0: # postscript generation
wolffd@0: #
wolffd@0: dops = function () {
wolffd@0:     local r;
wolffd@0: 
wolffd@0:     r = [0 = ['x' = 0; 'y' = 0;]; 1 = ['x' = 8 * 300; 'y' = 10.5 * 300;];];
wolffd@0:     canvas = opencanvas ('pscanvas', '', r);
wolffd@0:     setwidgetattr (canvas, ['window' = wrect;]);
wolffd@0:     redraw ();
wolffd@0:     closecanvas (canvas);
wolffd@0:     canvas=defcanvas;
wolffd@0: };
wolffd@0: init ();
wolffd@0: #txtview ('off');