From c0fe6750cc0462adbc2165ac7f8c9cf1e0aea925 Mon Sep 17 00:00:00 2001
From: Jules Laplace <jules@okfoc.us>
Date: Thu, 30 Oct 2014 17:59:44 -0400
Subject: intersection test

---
 public/assets/test/intersect.html | 132 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 132 insertions(+)
 create mode 100644 public/assets/test/intersect.html

(limited to 'public/assets/test/intersect.html')

diff --git a/public/assets/test/intersect.html b/public/assets/test/intersect.html
new file mode 100644
index 0000000..3f6d110
--- /dev/null
+++ b/public/assets/test/intersect.html
@@ -0,0 +1,132 @@
+<canvas id="canvas"></canvas>
+
+<script src="/assets/javascripts/util.js"></script>
+<script src="/assets/javascripts/vendor/tube.js"></script>
+<script src="/assets/javascripts/rectangles/util/constants.js"></script>
+<script src="/assets/javascripts/rectangles/util/mouse.js"></script>
+<script src="/assets/javascripts/rectangles/models/vec2.js"></script>
+<script src="/assets/javascripts/rectangles/models/rect.js"></script>
+<script src="/assets/javascripts/vendor/canvasutilities.js"></script>
+<script>
+
+var ctx = canvas.getContext('2d')
+
+var w = canvas.width = 600
+var h = canvas.height = 400
+
+var vec_a = new Rect( 100, 120, 50, 100 )
+var vec_b = new Rect( 20, 200, 120, 120 )
+var vecs = [ vec_a, vec_b ]
+var points = [ vec_a.x, vec_a.y, vec_b.x, vec_b.y ]
+var r = 4
+
+var vec_c = new Rect()
+vec_c.x = vec_a.x
+vec_c.y = vec_b.x
+
+var intersect = new vec2 ()
+
+var dragging = false, dragging_a, dragging_b
+var delta = new vec2( 0, 0 )
+
+var mymouse = new mouse({
+  el: canvas,
+  down: function(e, cursor){
+    points.some(function(p){
+      if (-cursor.x.a > p.a - r && -cursor.x.a < p.a + r &&
+           cursor.y.a > p.b - r &&  cursor.y.a < p.b + r) {
+        dragging_a = p.a
+        dragging_b = p.b
+        dragging = p
+        return true
+      }
+    })
+  },
+  drag: function(e, cursor){
+    if (! dragging) return
+    delta = cursor.delta()
+    delta.a = - delta.a
+    dragging.a = dragging_a + delta.a
+    dragging.b = dragging_b + delta.b
+  },
+  up: function(e, cursor, new_cursor){
+    delta.zero()
+    dragging.dragging = false
+    dragging = false
+  },
+})
+
+function draw () {
+  ctx.fillStyle = "#fff"
+  ctx.fillRect(0,0,w,h)
+  
+  ctx.fillStyle = "#bbb"
+  points.forEach(drawPoint)
+  
+  drawLine(vec_a.x, vec_a.y, "#f00")
+  drawLine(vec_b.x, vec_b.y, "#00f")
+  drawLine(vec_a.x, vec_b.x, "#080")
+
+  var t = perp(vec_c, vec_b) / ( perp(vec_a, vec_b) || 0.0000001 )
+  intersect.a = vec_a.x.a + ( vec_a.y.a - vec_a.x.a ) * t
+  intersect.b = vec_a.x.b + ( vec_a.y.b - vec_a.x.b ) * t
+  
+  var collinear = is_collinear( intersect.b, vec_b )
+  var long_enough_to_intersect = 0 <= t && t <= 1
+  
+  if (long_enough_to_intersect && collinear) {
+    ctx.fillStyle = "#f00"
+  }
+  else if (is_on_line) {
+    ctx.fillStyle = "#0f0"
+  }
+  else {
+    ctx.fillStyle = "#000"
+  }
+  
+  drawPoint(intersect)
+}
+function drawLine (pa, pb, color) {
+  ctx.fillStyle = color
+  ctx.strokeStyle = color
+  var x1 = pa.a
+  var y1 = pa.b
+  var x2 = pb.a
+  var y2 = pb.b
+  drawArrow(ctx, x1, y1, x2, y2)
+}
+function drawPoint (p) {
+  var x = p.a - r
+  var y = p.b - r
+  ctx.fillRect(x, y, r*2, r*2)
+}
+function perp (va, vb) {
+	return (va.y.a - va.x.a) * (vb.y.b - vb.x.b) - (va.y.b - va.x.b) * (vb.y.a - vb.x.a)
+}
+function is_collinear (n, vec) {
+  var on_x, on_y
+  
+  if (vec.x.a < vec.y.a) {
+    on_x = vec.x.a <= n && n <= vec.y.a
+  }
+  else {
+    on_x = vec.x.a >= n && n >= vec.y.a
+  }
+  
+  if (vec.x.b < vec.y.b) {
+    on_y = vec.x.b <= n && n <= vec.y.b
+  }
+  else {
+    on_y = vec.x.b >= n && n >= vec.y.b
+  }
+  
+  return !! (on_x && on_y)
+}
+
+function animate(){
+  requestAnimationFrame(animate)
+  draw()
+}
+animate()
+
+</script>
-- 
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