fix(modeling): fix line2.closestPoint

packages/modeling/src/maths/line2/closestPoint.js

@@ -12,20 +12,14 @@ const origin = require('./origin')
  * @alias module:modeling/maths/line2.closestPoint
  */
 const closestPoint = (line, point) => {
-  // linear function of AB
-  const a = origin(line)
-  const b = direction(line)
-  const m1 = (b[1] - a[1]) / (b[0] - a[0])
-  const t1 = a[1] - m1 * a[0]
-  // linear function of PC
-  const m2 = -1 / m1 // perpendicular
-  const t2 = point[1] - m2 * point[0]
-  // c.x * m1 + t1 === c.x * m2 + t2
-  const x = (t2 - t1) / (m1 - m2)
-  const y = m1 * x + t1
+  const orig = origin(line)
+  const dir = direction(line)
 
-  const closest = vec2.fromValues(x, y)
-  return closest
+  const v = vec2.subtract(vec2.create(), point, orig)
+  const dist = vec2.dot(v, dir)
+  vec2.scale(v, dir, dist)
+  vec2.add(v, v, orig)
+  return v
 }
 
 module.exports = closestPoint

packages/modeling/src/maths/line2/closestPoint.test.js

@@ -14,29 +14,35 @@ test('line2: closestPoint() should return proper values', (t) => {
 
   const line2 = fromPoints(create(), [-5, 5], [5, -5])
   const x4 = closestPoint(line2, [0, 0])
-  t.true(compareVectors(x4, [0.000000000000, 0.000000000000]))
+  t.true(compareVectors(x4, [0, 0]))
   const x5 = closestPoint(line2, [1, 0])
-  t.true(compareVectors(x5, [0.500000000000, -0.500000000000]))
+  t.true(compareVectors(x5, [0.5, -0.5]))
   const x6 = closestPoint(line2, [2, 0])
-  t.true(compareVectors(x6, [1.000000000000, -1.000000000000]))
+  t.true(compareVectors(x6, [1, -1]))
   const x7 = closestPoint(line2, [3, 0])
-  t.true(compareVectors(x7, [1.500000000000, -1.500000000000]))
+  t.true(compareVectors(x7, [1.5, -1.5]))
   const x8 = closestPoint(line2, [4, 0])
-  t.true(compareVectors(x8, [2.000000000000, -2.000000000000]))
+  t.true(compareVectors(x8, [2, -2]))
   const x9 = closestPoint(line2, [5, 0])
-  t.true(compareVectors(x9, [2.500000000000, -2.500000000000]))
+  t.true(compareVectors(x9, [2.5, -2.5]))
   const x10 = closestPoint(line2, [50, 0])
-  t.true(compareVectors(x10, [25.000000000000, -25.000000000000]))
+  t.true(compareVectors(x10, [25, -25]))
 
   const ya = closestPoint(line2, [-5, 5])
-  t.true(compareVectors(ya, [-5.000000000000, 5.000000000000]))
+  t.true(compareVectors(ya, [-5, 5]))
   const yb = closestPoint(line2, [5, -5])
-  t.true(compareVectors(yb, [5.000000000000, -5.000000000000]))
+  t.true(compareVectors(yb, [5, -5]))
 
   const za = closestPoint(line2, [4, -6])
-  t.true(compareVectors(za, [5.000000000000, -5.000000000000]))
+  t.true(compareVectors(za, [5, -5]))
   const zb = closestPoint(line2, [3, -7])
-  t.true(compareVectors(zb, [5.000000000000, -5.000000000000]))
+  t.true(compareVectors(zb, [5, -5]))
 
   t.true(true)
 })
+
+test('line2: closestPoint() should return proper values (issue #1225)', (t) => {
+  const line = fromPoints(create(), [10, 0], [0, 10])
+  const closest = closestPoint(line, [0, 0])
+  t.true(compareVectors(closest, [5, 5]))
+})

packages/modeling/src/maths/line2/direction.test.js

@@ -24,4 +24,8 @@ test('line2: direction() should return proper direction', (t) => {
   const line5 = fromPoints(create(), [-5, 5], [5, -5])
   const dir5 = direction(line5)
   t.true(compareVectors(dir5, [0.7071067811865475, -0.7071067811865475]))
+
+  const line6 = fromPoints(create(), [10, 0], [0, 10])
+  const dir6 = direction(line6)
+  t.true(compareVectors(dir6, [-0.7071067811865475, 0.7071067811865475]))
 })

packages/modeling/src/maths/line2/origin.js

@@ -2,6 +2,7 @@ const vec2 = require('../vec2')
 
 /**
  * Return the origin of the given line.
+ * The origin is the point on the line which is closest to the origin [0, 0].
  *
  * @param {line2} line - line of reference
  * @return {vec2} the origin of the line

packages/modeling/src/maths/line2/origin.test.js

@@ -23,4 +23,8 @@ test('line2: origin() should return proper origins', (t) => {
   const line5 = fromPoints(create(), [-5, 5], [5, -5])
   const org5 = origin(line5)
   t.true(compareVectors(org5, [0, 0]))
+
+  const line6 = fromPoints(create(), [10, 0], [0, 10])
+  const org6 = origin(line6)
+  t.true(compareVectors(org6, [5, 5]))
 })