bc.htm revision 235f56a92f6eb6accbb243e11b3c45e3798f38f2 
1<!-- bezier clip visualizer -->
2<html>
3<head>
4<div style="height:0">
5
6<div id="clip1">
7(gdb) p smaller
8$2 = {{
9    x = 0.91292418204644155, 
10    y = 0.41931201426549197
11  }, {
12    x = 0.70491388044579517, 
13    y = 0.64754305977710236
14  }, {
15    x = 0, 
16    y = 1
17  }}
18(gdb) p larger
19$3 = {{
20    x = 0.21875, 
21    y = 0.765625
22  }, {
23    x = 0.125, 
24    y = 0.875
25  }, {
26    x = 0, 
27    y = 1
28  }}
29(gdb) p distance2y
30$1 = {{
31    x = 0, 
32    y = 0.080355482722450078
33  }, {
34    x = 0.5, 
35    y = 0.038383741101172597
36  }, {
37    x = 1, 
38    y = 0
39  }}
40</div>
41
42<div id="quad21a">
43bezier_clip q1=(0,0 1,0 0,2) q2=(0.5,0.25 0.5,0.5 0,1) minT=0 maxT=1
44</div>
45<div id="quad21b">
46bezier_clip q1=(0.5,0.25 0.5,0.375 0.375,0.5625) q2=(0,0 1,0 0,2) minT=0.3 maxT=0.78125
47</div>
48<div id="quad21c">
49bezier_clip q1=(0.42,0.18 0.6125,0.46875 0.341796875,1.22070312) q2=(0.5,0.25 0.5,0.375 0.375,0.5625) minT=0 maxT=0.926710098
50</div>
51<div id="quad21d">
52bezier_clip q1=(0.5,0.25 0.5,0.307919381 0.473162762,0.379257381) q2=(0.42,0.18 0.6125,0.46875 0.341796875,1.22070312) minT=0.187231244 maxT=0.729263299
53</div>
54<div id="quad21e">
55bezier_clip q1=(0.475846194,0.304363878 0.53317904,0.507883959 0.454423387,0.847492538) q2=(0.5,0.25 0.5,0.307919381 0.473162762,0.379257381) minT=0 maxT=1
56</div>
57<div id="quad21f">
58bezier_clip q1=(0.493290691,0.311274036 0.486581381,0.343588381 0.473162762,0.379257381) q2=(0.475846194,0.304363878 0.53317904,0.507883959 0.454423387,0.847492538) minT=0.0828748517 maxT=0.150086861
59</div>
60
61<div id="quad21g">
62(gdb) p smaller
63$1 = {{
64    x = 0.48441440743366754, 
65    y = 0.33903196011243797
66  }, {
67    x = 0.48750982503868118, 
68    y = 0.35346899178071778
69  }, {
70    x = 0.48999046908865357, 
71    y = 0.368520797004039
72  }}
73(gdb) p larger
74$2 = {{
75    x = 0.49329069058425024, 
76    y = 0.31127403581536672
77  }, {
78    x = 0.48658138116850047, 
79    y = 0.34358838107698753
80  }, {
81    x = 0.47316276233700094, 
82    y = 0.37925738104648321
83  }}
84</div>
85
86</div>
87
88<script type="text/javascript">
89
90var testDivs = [
91    quad21g,
92    quad21a,
93    quad21b,
94    quad21c,
95    quad21d,
96    quad21e,
97    quad21f,
98    clip1,
99];
100
101var scale, columns, rows, xStart, yStart;
102
103var ticks = 0.1;
104var at_x = 13 + 0.5;
105var at_y = 13 + 0.5;
106var decimal_places = 0; // make this 3 to show more precision
107
108var tests = [];
109var testTitles = [];
110var testIndex = 0;
111var ctx;
112var fat1 = true;
113var fat2 = false;
114
115function parse(test, title) {
116    var curveStrs = test.split("{{");
117    if (curveStrs.length == 1)
118        curveStrs = test.split("=(");
119    var pattern = /[a-z$=]?-?\d+\.*\d*/g;
120    var curves = [];
121    for (var c in curveStrs) {
122        var curveStr = curveStrs[c];
123        var points = curveStr.match(pattern);
124        var pts = [];
125        for (var wd in points) {
126            var num = parseFloat(points[wd]);
127            if (isNaN(num)) continue;
128            pts.push(num);
129        }
130        if (pts.length > 0)
131            curves.push(pts);
132    }
133    if (curves.length >= 2) {
134        tests.push(curves);
135        testTitles.push(title);
136    }
137}
138
139function init(test) {
140    var canvas = document.getElementById('canvas');
141    if (!canvas.getContext) return;
142    canvas.width = window.innerWidth - at_x;
143    canvas.height = window.innerHeight - at_y;
144    ctx = canvas.getContext('2d');
145    var xmin = Infinity;
146    var xmax = -Infinity;
147    var ymin = Infinity;
148    var ymax = -Infinity;
149    for (var curves in test) {
150        var curve = test[curves];
151        var last = curve.length;
152        for (var idx = 0; idx < last; idx += 2) {
153            xmin = Math.min(xmin, curve[idx]);
154            xmax = Math.max(xmax, curve[idx]);
155            ymin = Math.min(ymin, curve[idx + 1]);
156            ymax = Math.max(ymax, curve[idx + 1]);
157        }
158    }
159    var subscale = 1;
160    if (xmax != xmin && ymax != ymin) {
161        while ((xmax - xmin) * subscale < 0.1 && (ymax - ymin) * subscale < 0.1) {
162            subscale *= 10;
163            if (subscale > 100000) {
164                break;
165            }
166        }
167    }
168    columns = Math.ceil(xmax) - Math.floor(xmin) + 1;
169    rows = Math.ceil(ymax) - Math.floor(ymin) + 1;
170    xStart = Math.floor(xmin);
171    yStart = Math.floor(ymin);
172    var hscale = ctx.canvas.width / columns / ticks;
173    var vscale = ctx.canvas.height / rows / ticks;
174    scale = Math.floor(Math.min(hscale, vscale)) * subscale;
175}
176
177function drawPoint(px, py, xoffset, yoffset, unit) {
178    var label = px.toFixed(decimal_places) + ", " + py.toFixed(decimal_places);
179    var _px = px * unit + xoffset;
180    var _py = py * unit + yoffset;
181    ctx.beginPath();
182    ctx.arc(_px, _py, 3, 0, Math.PI*2, true);
183    ctx.closePath();
184    ctx.fill();
185    ctx.fillText(label, _px + 5, _py);
186}
187
188function draw(test, title, _at_x, _at_y, scale) {
189    ctx.fillStyle = "rgba(0,0,0, 0.1)";
190    ctx.font = "normal 50px Arial";
191    ctx.fillText(title, 50, 50);
192    ctx.font = "normal 10px Arial";
193
194    var unit = scale * ticks;
195    ctx.lineWidth = 1;
196    var i;
197    for (i = 0; i <= rows * ticks; ++i) {
198        ctx.strokeStyle = (i % ticks) != 0 ? "rgb(160,160,160)" : "black";
199        ctx.beginPath();
200        ctx.moveTo(_at_x + 0, _at_y + i * scale);
201        ctx.lineTo(_at_x + unit * columns, _at_y + i * scale);
202        ctx.stroke();
203    }
204    for (i = 0; i <= columns * ticks; ++i) {
205        ctx.strokeStyle = (i % ticks) != 0 ? "rgb(160,160,160)" : "black";
206        ctx.beginPath();
207        ctx.moveTo(_at_x + i * scale, _at_y + 0);
208        ctx.lineTo(_at_x + i * scale, _at_y + unit * rows);
209        ctx.stroke();
210    }
211 
212    var xoffset = xStart * -unit + _at_x;
213    var yoffset = yStart * -unit + _at_y;
214
215    ctx.fillStyle = "rgb(40,80,60)"
216    for (i = 0; i <= columns; i += (1 / ticks))
217    {
218        num = (xoffset - _at_x) / -unit + i; 
219        ctx.fillText(num.toFixed(0), i * unit + _at_y - 5, 10);
220    }
221    for (i = 0; i <= rows; i += (1 / ticks))
222    {
223        num = (yoffset - _at_x) / -unit + i; 
224        ctx.fillText(num.toFixed(0), 0, i * unit + _at_y + 0);
225    }
226
227    // draw curve 1 and 2
228    var curves, pts;
229    for (curves in test) {
230        var curve = test[curves];
231        ctx.beginPath();
232        ctx.moveTo(xoffset + curve[0] * unit, yoffset + curve[1] * unit);
233        switch (curve.length) {
234            case 6:
235                ctx.quadraticCurveTo(
236                    xoffset + curve[2] * unit, yoffset + curve[3] * unit,
237                    xoffset + curve[4] * unit, yoffset + curve[5] * unit);
238                break;
239            case 8:
240                ctx.bezierCurveTo(
241                    xoffset + curve[2] * unit, yoffset + curve[3] * unit,
242                    xoffset + curve[4] * unit, yoffset + curve[5] * unit,
243                    xoffset + curve[6] * unit, yoffset + curve[7] * unit);
244                break;
245        }
246        if (curves == 2) ctx.strokeStyle = curves ? "red" : "blue";
247        ctx.stroke();
248        ctx.strokeStyle = "rgba(0,0,0, 0.3)";
249        ctx.beginPath();
250        ctx.moveTo(xoffset + curve[0] * unit, yoffset + curve[1] * unit);
251        ctx.lineTo(xoffset + curve[2] * unit, yoffset + curve[3] * unit);
252        ctx.lineTo(xoffset + curve[4] * unit, yoffset + curve[5] * unit);
253        if (curve.length == 8)
254            ctx.lineTo(xoffset + curve[6] * unit, yoffset + curve[7] * unit);
255        ctx.stroke();
256    }
257    // optionally draw fat lines for curve 
258    if (fat1)
259        drawFat(test[0], xoffset, yoffset, unit);
260    if (fat2)
261        drawFat(test[1], xoffset, yoffset, unit);
262}
263
264function drawFat(curve, xoffset, yoffset, unit) {
265    var last = curve.length - 2;
266    ctx.strokeStyle = "rgba(0,0,0, 0.5)";
267    ctx.beginPath();
268    ctx.moveTo(xoffset + curve[0] * unit, yoffset + curve[1] * unit);
269    ctx.lineTo(xoffset + curve[last] * unit, yoffset + curve[last + 1] * unit);
270    ctx.stroke();
271    // draw line parallel to end points through control points
272    var dx = curve[last] - curve[0];
273    var dy = curve[last + 1] - curve[1];
274    drawParallelLine(curve[2], curve[3], dx, dy, xoffset, yoffset, unit);
275    if (curve.length == 8)
276        drawParallelLine(curve[4], curve[5], dx, dy, xoffset, yoffset, unit);
277}
278
279function drawParallelLine(x, y, dx, dy, xoffset, yoffset, unit) {
280    var x1 = x - dx;
281    var y1 = y - dy;
282    var x2 = x + dx;
283    var y2 = y + dy;
284    ctx.beginPath();
285    ctx.moveTo(xoffset + x1 * unit, yoffset + y1 * unit);
286    ctx.lineTo(xoffset + x2 * unit, yoffset + y2 * unit);
287    ctx.stroke();
288}
289
290function drawTop() {
291    init(tests[testIndex]);
292    redraw();
293}
294
295function redraw() {
296    ctx.beginPath();
297    ctx.rect(0, 0, ctx.canvas.width, ctx.canvas.height);
298    ctx.fillStyle="white";
299    ctx.fill();
300    draw(tests[testIndex], testTitles[testIndex], at_x, at_y, scale);
301}
302
303function doKeyPress(evt) {
304    var char = String.fromCharCode(evt.charCode);
305    switch (char) {
306    case 'f':
307        fat2 ^= true;
308        if (fat2 == false)
309            fat1 ^= true;
310        drawTop();
311        break;
312    case 'N':
313        testIndex += 9;
314    case 'n':
315        if (++testIndex >= tests.length)
316            testIndex = 0;
317        mouseX = Infinity;
318        drawTop();
319        break;
320    case 'P':
321        testIndex -= 9;
322    case 'p':
323        if (--testIndex < 0)
324            testIndex = tests.length - 1;
325        mouseX = Infinity;
326        drawTop();
327        break;
328    }
329}
330
331function handleMouseClick() {
332}
333
334function handleMouseOver() {
335}
336
337function start() {
338    for (i = 0; i < testDivs.length; ++i) {
339        var title = testDivs[i].id.toString();
340        var str = testDivs[i].firstChild.data;
341        parse(str, title);
342    }
343    drawTop();
344    window.addEventListener('keypress', doKeyPress, true);
345    window.onresize = function() {
346        drawTop();
347    }
348}
349
350</script>
351</head>
352
353<body onLoad="start();">
354<canvas id="canvas" width="750" height="500"
355    onmousemove="handleMouseOver()"
356    onclick="handleMouseClick()"
357    ></canvas >
358</body>
359</html>
360