From: Daniel Karbach <daniel.karbach@localhorst.tv>
Date: Wed, 9 May 2012 18:43:46 +0000 (+0000)
Subject: extracted some parts of the collision response for better readability
X-Git-Url: https://git.localhorst.tv/?a=commitdiff_plain;h=dae78ac0fb4ecebb1ab9f2d2d1b04420ccd5d4f7;p=sdl-test8.git

extracted some parts of the collision response for better readability
---

diff --git a/src/game/Entity.cpp b/src/game/Entity.cpp
index 1c3f785..ebc812e 100644
--- a/src/game/Entity.cpp
+++ b/src/game/Entity.cpp
@@ -71,6 +71,8 @@ void Entity::CollisionResponse(Entity &a, const Ray &na, Entity &b) {
 
 	const Scalar e(1);
 
+	const Vector normal(na.Direction());
+
 	const Vector va(a.LinearVelocity());
 	const Vector vb(b.LinearVelocity());
 	const Scalar wa(a.AngularVelocity());
@@ -80,25 +82,33 @@ void Entity::CollisionResponse(Entity &a, const Ray &na, Entity &b) {
 	const Vector vbp(b.VelocityAt(na.Origin()));
 	const Vector vab = vap - vbp;
 
+	const Vector restitutionVAB((-(1 + e)) * vab);
+
 	const Vector rap90((na.Origin() - a.Origin()).Rotate90());
 	const Vector rbp90((na.Origin() - b.Origin()).Rotate90());
 
-	const Scalar ia(a.Mass());
+	const Scalar ia(a.Mass()); // inertia equals mass? probably not
 	const Scalar ib(b.Mass());
 
+	const Scalar aInverseMass(1.0 / a.Mass());
+	const Scalar bInverseMass(1.0 / b.Mass());
+
 	const Scalar rap90dotN(rap90.Dot(na.Direction()));
 	const Scalar rbp90dotN(rbp90.Dot(na.Direction()));
 
+	const Scalar aRotationalPart((rap90dotN * rap90dotN) / ia);
+	const Scalar bRotationalPart((rbp90dotN * rbp90dotN) / ib);
+
 	const Scalar j(
-			(((-(1 + e)) * vab).Dot(na.Direction()))
-			/ (na.Direction().Dot(na.Direction() * ((1.0 / a.Mass()) + (1.0 / b.Mass())))
-					+ ((rap90dotN * rap90dotN) / ia)
-					+ ((rbp90dotN * rbp90dotN) / ib) ));
+			restitutionVAB.Dot(normal)
+			/ (normal.Dot(normal * (aInverseMass + bInverseMass))
+					+ aRotationalPart
+					+ bRotationalPart ));
 
-	const Vector va2(va + ((j / a.Mass()) * na.Direction()));
-	const Vector vb2(vb - ((j / b.Mass()) * na.Direction()));
-	const Scalar wa2(wa + ((rap90.Dot(j * na.Direction())) / ia));
-	const Scalar wb2(wb - ((rbp90.Dot(j * na.Direction())) / ib));
+	const Vector va2(va + (j / a.Mass()) * normal);
+	const Vector vb2(vb - (j / b.Mass()) * normal);
+	const Scalar wa2(wa + rap90.Dot(j * normal) / ia);
+	const Scalar wb2(wb - rbp90.Dot(j * normal) / ib);
 
 	a.linearVelocity = va2;
 	a.angularVelocity = wa2;
@@ -109,6 +119,7 @@ void Entity::CollisionResponse(Entity &a, const Ray &na, Entity &b) {
 void Entity::InfInfCollisionResponse(Entity &a, const Ray &na, Entity &b) {
 	// If both elements are standing still or both are moving, move them away
 	// from each other. Otherwise, move the moving one.
+	// This will keep the paddle from bouncing off the wall at infinite velocity.
 	if ((a.linearVelocity == Vector() && b.linearVelocity == Vector())
 			|| (a.linearVelocity != Vector() && b.linearVelocity != Vector())) {
 		a.Translate(na.Direction());
diff --git a/src/pong/Match.cpp b/src/pong/Match.cpp
index 5754b36..523c2fd 100644
--- a/src/pong/Match.cpp
+++ b/src/pong/Match.cpp
@@ -34,8 +34,8 @@ Match::Match(void)
 , worldWidth(800)
 , worldHeight(480)
 , ball(10)
-, secondBall(7)
-, thirdBall(5)
+, secondBall(8)
+, thirdBall(7)
 , leftPaddle(10, 100)
 , rightPaddle(10, 100)
 , topWall(800, 10)
@@ -51,15 +51,15 @@ Match::Match(void)
 	}
 
 	ball.Translate(Entity::Vector(400, 240));
-	ball.Accelerate(Entity::Vector(180, 180));
+	ball.Accelerate(Entity::Vector(180, 180), 0);
 //	ball.SetMaxVelocity(500.0f);
 
 	secondBall.Translate(Entity::Vector(300, 240));
-	secondBall.Accelerate(Entity::Vector(-50, -50), 1);
+	secondBall.Accelerate(Entity::Vector(-50, -50), -3);
 //	secondBall.SetMaxVelocity(600.0f);
 
 	thirdBall.Translate(Entity::Vector(200, 440));
-	thirdBall.Accelerate(Entity::Vector(60, 40));
+	thirdBall.Accelerate(Entity::Vector(60, 40), 3);
 
 	leftPaddle.Translate(Entity::Vector(5, 200));
 	rightPaddle.Translate(Entity::Vector(795, 280));