Merge pull request #8 from ThalesGroup/master

Update distanceTo method for GSegment

Author: jecisc

src/.properties

@@ -1,3 +1,4 @@
 {
-	#format : #tonel
-}
+	#format : #tonel,
+	#version : #'1.0'
+}

src/Geometry-Tests/GSegmentTest.class.st

@@ -44,7 +44,10 @@ GSegmentTest >> testDistanceTo [
 	self assert: ((GSegment with: -2 , 4 with: 2 , 4) distanceTo: -2 , 4) equals: 0.
 	self assert: ((GSegment with: -2 , 4 with: 2 , 4) distanceTo: 2 , 4) equals: 0.
 	self assert: ((GSegment with: 477 / 11 , (149 / 2) with: -56.73661227723915 , 143.3189209406019) distanceTo: 36819 / 1022 , (82249 / 1022)) =~ 0.7697676365059569.
-	self assert: ((GSegment with: 838 / 41 , (4811 / 82) with: 57583 / 914 , (56095 / 914)) distanceTo: 57.998905906959145 , 61.11074842728413) =~ (2 * 0.02757564283371476)
+	self assert: ((GSegment with: 838 / 41 , (4811 / 82) with: 57583 / 914 , (56095 / 914)) distanceTo: 57.998905906959145 , 61.11074842728413) =~ (2 * 0.02757564283371476).
+	
+	self assert: ((GSegment with: -2 , 4 with: 2 , 4) distanceTo: 3 , 4) equals: 1.
+	self assert: ((GSegment with: -2 , 4 with: 2 , 4) distanceTo: -2 , 5) equals: 1.
 ]
 
 { #category : #tests }

src/Geometry/GSegment.class.st

@@ -68,10 +68,31 @@ GSegment >> asGLine [
 
 { #category : #properties }
 GSegment >> distanceTo: aGPoint [
-	self flag: #todo.	"«The distance between segments and rays may not be the same as the distance between their extended lines. » http://geomalgorithms.com/a07-_distance.html
+
+	| vectSegment vectPoint t distance closestPoint|
+
+	"See:https://paulbourke.net/geometry/pointlineplane/
+	and: https://gist.github.com/mattdesl/47412d930dcd8cd765c871a65532ffac"
+
+	distance := SmallInteger maxVal.
+	
+	"Vector from v1 to v2"
+	vectSegment := (v2 asPoint) - (v1 asPoint).
+	vectSegment isZero ifTrue:[ ^distance ].
+	"Vector from v1 to P"
+	vectPoint := (aGPoint asPoint) - (v1 asPoint).
+	t := (vectSegment dotProduct: vectPoint) / (vectSegment dotProduct: vectSegment).
+	"Clamp t to [0, 1] to restrict to the segment"
+	t := (t max: 0) min: 1.
+	
+	"Closest point on segment to P"
+	closestPoint := (v1 asPoint) + (vectSegment * t).
+	distance := (aGPoint asPoint) distanceTo: closestPoint.
+	
+	^distance
+	
+	
 
-	So apparently this implementation is wrong."
-	^ self asGLine distanceTo: aGPoint
 ]
 
 { #category : #comparing }