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<style>
body,html{margin:0;padding:0;}
#hud { position: absolute; top: 0; left: 0; pointer-events: none; }
canvas { position: absolute; top: 0; left: 0; cursor: crosshair; }
#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="../javascripts/vendor/bower_components/jquery/dist/jquery.min.js"></script>
<script src="../javascripts/vendor/bower_components/lodash/dist/lodash.min.js"></script>
<script src="../javascripts/vendor/canvasutilities.js"></script>
<script src="../javascripts/vendor/jsBezier-0.6.js"></script>
<script src="../javascripts/vendor/tube.js"></script>
<script src="../javascripts/math/util.js"></script>
<script src="../javascripts/math/point.js"></script>
<script src="../javascripts/math/vec2.js"></script>
<script src="../javascripts/util/mouse.js"></script>
<script src="../javascripts/util/keys.js"></script>
<script src="../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 radius = 1
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 drawBrush = drawRoundBrush
keys.on("open_bracket", function(){
radius = max(radius-1, 1)
drawBrush(radius)
})
keys.on("close_bracket", function(){
radius = min(radius+1, 100)
drawBrush(radius)
})
keys.on("forward_slash", function(){
drawBrush = drawBrush == drawRoundBrush ? drawSquareBrush : drawRoundBrush
drawBrush(radius)
})
var extra = 1
function drawLine (u, v) {
var radius = scratch.width/2
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 drawSquareBrush (w, h) {
w = w || 1
h = h || w
scratch.width = w
scratch.height = h
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
d[t] = d[t+1] = d[t+2] = 0
d[t+3] = 255
}
}
scratchCtx.putImageData(imagedata, 0, 0)
}
function drawRoundBrush (diameter) {
var w = scratch.width = diameter
var h = scratch.height = diameter
var radius = diameter/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 + 0.5
p.y = j - radius + 0.5
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] = 255
}
}
}
scratchCtx.putImageData(imagedata, 0, 0)
}
for (var i = 0; i < 11; i++) {
drawSquareBrush(i+1)
drawLine( new point( 100, 100 + 40 * i), new point (400, 100 + 40 * i ))
}
drawSquareBrush(radius = 2)
// 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>
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