From ef33a17b6a4349786e1825a2b5dc88f918cfa362 Mon Sep 17 00:00:00 2001
From: Fraser Graham <fraser_graham@apple.com>
Date: Wed, 13 Jul 2016 12:16:10 -0600
Subject: [PATCH] Remove special case wall collisions, replace with generated
 objects

---
 obstacle.go | 35 ++++++++++++++++++++++++++---------
 robot.go    | 23 +----------------------
 2 files changed, 27 insertions(+), 31 deletions(-)

diff --git a/obstacle.go b/obstacle.go
index f188ee4..ad6c19a 100644
--- a/obstacle.go
+++ b/obstacle.go
@@ -49,24 +49,41 @@ func (o Obstacle) distance_from_point(p v.Point2d) float64 {
 	return dist
 }
 
+func obstacleFromValues(x, y, w, h float64, hp int) (o Obstacle) {
+	return Obstacle{
+		Bounds: v.AABB2d{
+			A: v.Point2d{X: x, Y: y},
+			B: v.Point2d{X: x + w, Y: y + h},
+		},
+		Hp: hp,
+	}
+}
+
 // GenerateObstacles returns a slice of (count) obstacles within a region
 // bounded by width, height.
 func GenerateObstacles(count int, width, height float64) []Obstacle {
 	out := []Obstacle{}
+
+	// Create obstacles that cover the edges of the world, so we don't need to
+	// special case collision at the edges
+	// left wall
+	out = append(out, obstacleFromValues(0, 5, 5, height-10, 0))
+	// // right wall
+	out = append(out, obstacleFromValues(width-5, 5, 5, height-10, 0))
+	// // top wall
+	out = append(out, obstacleFromValues(0, height-5, width, 5, 0))
+	// bottom wall
+	out = append(out, obstacleFromValues(0, 0, width, 5, 0))
+
+	// Now create N random objects somewhere in the world
 	for i := 0; i < count; i++ {
 		x := rand.Float64() * (width - (width / 10))
 		y := rand.Float64() * (height - (height / 10))
-		w := rand.Float64() * (width / 10)
-		h := rand.Float64() * (height / 10)
+		w := rand.Float64()*(width/10) + 20
+		h := rand.Float64()*(height/10) + 20
 		out = append(
 			out,
-			Obstacle{
-				Bounds: v.AABB2d{
-					A: v.Point2d{X: x, Y: y},
-					B: v.Point2d{X: 20 + x + w, Y: 20 + y + h},
-				},
-				Hp: 10000,
-			})
+			obstacleFromValues(x, y, w, h, 10000))
 	}
 	return out
 }
diff --git a/robot.go b/robot.go
index 2ddfd84..3497b69 100644
--- a/robot.go
+++ b/robot.go
@@ -195,29 +195,8 @@ func (r *Robot) checkCollisions(g *Game, probe v.Vector2d) (bool, *v.Point2d, *R
 	botSize := 5.0
 	botPolygon := v.OrientedSquare(r.Position, r.Heading, botSize)
 
-	bounds := []Obstacle{
-		Obstacle{
-			Bounds: v.AABB2d{A: v.Point2d{0, 0}, B: v.Point2d{0, g.width}},
-			Hp:     0,
-		},
-		Obstacle{
-			Bounds: v.AABB2d{A: v.Point2d{0, 0}, B: v.Point2d{0, g.height}},
-			Hp:     0,
-		},
-		Obstacle{
-			Bounds: v.AABB2d{A: v.Point2d{g.width, g.height}, B: v.Point2d{0, g.height}},
-			Hp:     0,
-		},
-		Obstacle{
-			Bounds: v.AABB2d{A: v.Point2d{g.width, g.height}, B: v.Point2d{g.width, 0}},
-			Hp:     0,
-		},
-	}
-
-	obstacles := append(g.obstacles, bounds...)
-
 	// Check Obstacles
-	for _, obj := range obstacles {
+	for _, obj := range g.obstacles {
 		// collision due to motion:
 		collision, move_collision, translation := v.PolyPolyIntersection(
 			botPolygon, probe, obj.Bounds.ToPolygon())