From 09bce076cc950e836ad79f6120ad2b95c069749a Mon Sep 17 00:00:00 2001
From: Andrew Meadows <andrew@highfidelity.io>
Date: Wed, 15 Jan 2014 14:06:31 -0800
Subject: [PATCH] All avatars now have disk collision proxies at their hands.

---
 .../particles/src/ParticleCollisionSystem.cpp | 47 ++++++-------------
 1 file changed, 14 insertions(+), 33 deletions(-)

diff --git a/libraries/particles/src/ParticleCollisionSystem.cpp b/libraries/particles/src/ParticleCollisionSystem.cpp
index 7d199d3c38..417c1e0667 100644
--- a/libraries/particles/src/ParticleCollisionSystem.cpp
+++ b/libraries/particles/src/ParticleCollisionSystem.cpp
@@ -137,15 +137,14 @@ void ParticleCollisionSystem::updateCollisionWithParticles(Particle* particleA)
 
 void ParticleCollisionSystem::updateCollisionWithAvatars(Particle* particle) {
 
-    // particles that are in hand, don't collide with other avatar parts
+    // particles that are in hand, don't collide with avatars
     if (particle->getInHand()) {
         return;
     }
 
-    //printf("updateCollisionWithAvatars()...\n");
     glm::vec3 center = particle->getPosition() * (float)(TREE_SCALE);
     float radius = particle->getRadius() * (float)(TREE_SCALE);
-    const float ELASTICITY = 0.4f;
+    const float ELASTICITY = 0.95f;
     const float DAMPING = 0.0f;
     const float COLLISION_FREQUENCY = 0.5f;
     glm::vec3 penetration;
@@ -157,55 +156,37 @@ void ParticleCollisionSystem::updateCollisionWithAvatars(Particle* particle) {
         CollisionInfo collision;
         if (avatar->findSphereCollision(center, radius, collision)) {
             if (glm::dot(particle->getVelocity(), collision._addedVelocity) < 0.f) {
+                // only collide when particle and collision point are moving toward each other
                 collision._penetration /= (float)(TREE_SCALE);
                 collision._addedVelocity /= (float)(TREE_SCALE);
-                glm::vec3 pv = particle->getVelocity();
                 updateCollisionSound(particle, collision._penetration, COLLISION_FREQUENCY);
                 applyHardCollision(particle, collision._penetration, ELASTICITY, DAMPING, collision._addedVelocity);    
             }
         }
     }
 
-    // TODO: convert other avatars to collide like _selfAvatar
-
     // loop through all the other avatars for potential interactions...
-    
     foreach (const SharedNodePointer& node, NodeList::getInstance()->getNodeHash()) {
         //qDebug() << "updateCollisionWithAvatars()... node:" << *node << "\n";
         if (node->getLinkedData() && node->getType() == NODE_TYPE_AGENT) {
-            // TODO: dot collidingPalm and hand velocities and skip collision when they are moving apart.
             AvatarData* avatar = static_cast<AvatarData*>(node->getLinkedData());
-            //printf("updateCollisionWithAvatars()...avatar=%p\n", avatar);
-            
-            // check hands...
-            const HandData* handData = avatar->getHandData();
-            
-            if (handData->findSpherePenetration(center, radius, penetration, collidingPalm)) {
-                // apply a hard collision when ball collides with hand
-                penetration /= (float)(TREE_SCALE);
-                updateCollisionSound(particle, penetration, COLLISION_FREQUENCY);
-                
-                // determine if the palm that collided was moving, if so, then we add that palm velocity as well...
-                glm::vec3 addedVelocity = NO_ADDED_VELOCITY;
-                if (collidingPalm) {
-                    glm::vec3 palmVelocity = collidingPalm->getVelocity() / (float)(TREE_SCALE);
-                    //printf("collidingPalm Velocity=%f,%f,%f\n", palmVelocity.x, palmVelocity.y, palmVelocity.z);
-                    addedVelocity = palmVelocity;
+
+            CollisionInfo collision;
+            if (avatar->findSphereCollision(center, radius, collision)) {
+                if (glm::dot(particle->getVelocity(), collision._addedVelocity) < 0.f) {
+                    // only collide when particle and collision point are moving toward each other
+                    collision._penetration /= (float)(TREE_SCALE);
+                    collision._addedVelocity /= (float)(TREE_SCALE);
+                    updateCollisionSound(particle, collision._penetration, COLLISION_FREQUENCY);
+                    applyHardCollision(particle, collision._penetration, ELASTICITY, DAMPING, collision._addedVelocity);    
                 }
-                
-                applyHardCollision(particle, penetration, ELASTICITY, DAMPING, addedVelocity);
-                
-            } else if (avatar->findSpherePenetration(center, radius, penetration)) {
-                penetration /= (float)(TREE_SCALE);
-                updateCollisionSound(particle, penetration, COLLISION_FREQUENCY);
-                glm::vec3 addedVelocity = avatar->getVelocity();
-                applyHardCollision(particle, penetration, ELASTICITY, DAMPING, addedVelocity);
             }
         }
     }
 }
 
 
+// TODO: convert applyHardCollision() to take a CollisionInfo& instead of penetration + addedVelocity
 void ParticleCollisionSystem::applyHardCollision(Particle* particle, const glm::vec3& penetration,
                                                  float elasticity, float damping, const glm::vec3& addedVelocity) {
     //
@@ -221,7 +202,7 @@ void ParticleCollisionSystem::applyHardCollision(Particle* particle, const glm::
     const float EPSILON = 0.0f;
     float velocityDotPenetration = glm::dot(velocity, penetration);
     if (velocityDotPenetration > EPSILON) {
-        position -= penetration;
+        //position -= penetration;
         static float HALTING_VELOCITY = 0.2f / (float)(TREE_SCALE);
         // cancel out the velocity component in the direction of penetration