Merge pull request #236 from bcvery1/master

Fixing line intersection for lines through origin

CHANGELOG.md

@@ -5,6 +5,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 ## [Unreleased]
 - Gamepad API?
+- Fixed Line intersects failing on lines passing through (0, 0)
 
 ## [v0.10.0-alpha] 2020-05-08
 - Upgrade to GLFW 3.3! :tada:

geometry.go

@@ -406,12 +406,12 @@ func (l Line) IntersectRect(r Rect) Vec {
 			//  - the point is contained by the rectangle
 			//  - the point is not the corner itself
 			corners := r.Vertices()
-			closest := ZV
+			var closest *Vec
 			closestCorner := corners[0]
 			for _, c := range corners {
 				cc := l.Closest(c)
-				if closest == ZV || (closest.Len() > cc.Len() && r.Contains(cc)) {
+				if closest == nil || (closest.Len() > cc.Len() && r.Contains(cc)) {
-					closest = cc
+					closest = &cc
 					closestCorner = c
 				}
 			}

geometry_test.go

@@ -1002,6 +1002,18 @@ func TestLine_Closest(t *testing.T) {
 			args:   args{v: pixel.V(20, 20)},
 			want:   pixel.V(10, 10),
 		},
+		{
+			name:   "Vertical line",
+			fields: fields{A: pixel.V(0, -10), B: pixel.V(0, 10)},
+			args:   args{v: pixel.V(-1, 0)},
+			want:   pixel.V(0, 0),
+		},
+		{
+			name:   "Horizontal line",
+			fields: fields{A: pixel.V(-10, 0), B: pixel.V(10, 0)},
+			args:   args{v: pixel.V(0, -1)},
+			want:   pixel.V(0, 0),
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -1297,6 +1309,12 @@ func TestLine_IntersectRect(t *testing.T) {
 			args:   args{r: pixel.R(20, 20, 21, 21)},
 			want:   pixel.ZV,
 		},
+		{
+			name:   "Line intersects at 0,0",
+			fields: fields{A: pixel.V(0, -10), B: pixel.V(0, 10)},
+			args:   args{r: pixel.R(-1, 0, 2, 2)},
+			want:   pixel.V(-1, 0),
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {