1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
|
<style>
body,html{margin:0;padding:0;}
#hud { position: absolute; top: 0; left: 0; pointer-events: none; }
canvas { position: absolute; top: 0; left: 0; }
#mask { pointer-events: none; }
#scratch { display: none; }
</style>
<canvas id="canvas"></canvas>
<canvas id="mask"></canvas>
<canvas id="scratch"></canvas>
<div id="hud"></div>
<script src="/assets/javascripts/vendor/bower_components/jquery/dist/jquery.min.js"></script>
<script src="/assets/javascripts/vendor/bower_components/lodash/dist/lodash.min.js"></script>
<script src="/assets/javascripts/vendor/canvasutilities.js"></script>
<script src="/assets/javascripts/vendor/jsBezier-0.6.js"></script>
<script src="/assets/javascripts/vendor/tube.js"></script>
<script src="/assets/javascripts/math/util.js"></script>
<script src="/assets/javascripts/math/point.js"></script>
<script src="/assets/javascripts/math/vec2.js"></script>
<script src="/assets/javascripts/util/mouse.js"></script>
<script src="/assets/javascripts/util/uid.js"></script>
<script>
var ctx = canvas.getContext('2d')
var maskCtx = mask.getContext('2d')
var scratchCtx = scratch.getContext('2d')
var w = mask.width = canvas.width = window.innerWidth
var h = mask.height = canvas.height = window.innerHeight
var drawing = false
var lastPoint = new point (0, 0), newPoint = new point (0, 0)
var mymouse = new mouse({
el: canvas,
down: function(e, cursor){
drawing = true
lastPoint.x = cursor.a.x
lastPoint.y = cursor.a.y
maskCtx.clearRect(0,0,w,h)
extra = 1
drawLine(lastPoint, lastPoint)
// imagedata = ctx.getImageData( 0, 0, canvas.width, canvas.height )
// data = imagedata.data
},
drag: function(e, cursor){
newPoint.x = cursor.b.x
newPoint.y = cursor.b.y
drawLine(lastPoint, newPoint)
lastPoint.x = newPoint.x
lastPoint.y = newPoint.y
},
up: function(e, cursor, new_cursor){
drawing = false
// ctx.globalCompositeOperation = "multiply"
ctx.drawImage(mask, 0, 0)
maskCtx.clearRect(0,0,w,h)
},
})
var extra = 1
function drawLine (u, v) {
var radius = 20
var length = sqrt(dist2(u, v))
var steps = length / (scratch.width/4) + extra
extra = steps % 1
if (steps < 1) return
var x, y, t
for (var i = 0; i < steps; i++) {
t = i/steps
x = lerp(t, u.x, v.x)
y = lerp(t, u.y, v.y)
maskCtx.drawImage(scratch, x - radius, y - radius)
}
}
function drawBrush () {
var radius = 20
var w = scratch.width = radius*2
var h = scratch.height = radius*2
var p = new point (0,0)
var radius2 = radius * radius
var imagedata = ctx.createImageData(w, h)
var d = imagedata.data
var i, j, t, dist
for (i = 0; i < w; i++) {
for (j = 0; j < h; j++) {
t = (j * w + i) * 4
p.x = i - radius
p.y = j - radius
dist = distToSegmentSquared( p, { x: 0, y: 0 }, { x: 0, y: 0 } )
if (dist > radius2) {
d[t] = d[t+1] = d[t+2] = d[t+3] = 0
}
else {
d[t] = d[t+1] = d[t+2] = 0
d[t+3] = round( (1 - bezier( sqrt(dist)/radius, 0, 0, 1, 1)) * 255)
}
}
}
scratchCtx.putImageData(imagedata, 0, 0)
}
drawBrush()
for (var i = 0; i < 11; i++) {
drawLine( new point( 100, 100 + 40 * i), new point (400, 100 + 40 * i ))
}
// drawLine( new point( 100, 100 ), new point( 100, 400 ) )
// drawLine( new point( 100, 100 ), new point( 400, 100 ) )
// drawLine( new point( 100, 100 ), new point( 400, 400 ) )
function bezier(t,a,b,c,d) {
var s = (1-t)
return s*s*s*a + 3*s*s*b + 3*s*t*t*c + t*t*t*d
}
function sqr(x) { return x * x }
function dist2(v, w) { return sqr(v.x - w.x) + sqr(v.y - w.y) }
function distToSegmentSquared (p, v, w) {
var l2 = dist2(v, w)
if (l2 == 0) return dist2(p, v)
var t = ((p.x - v.x) * (w.x - v.x) + (p.y - v.y) * (w.y - v.y)) / l2
if (t < 0) return dist2(p, v)
if (t > 1) return dist2(p, w)
return dist2(p, { x: v.x + t * (w.x - v.x),
y: v.y + t * (w.y - v.y) })
}
</script>
|
