diff --git a/interface/src/avatar/Avatar.cpp b/interface/src/avatar/Avatar.cpp
index 6c8a177c99..3f585d8da4 100644
--- a/interface/src/avatar/Avatar.cpp
+++ b/interface/src/avatar/Avatar.cpp
@@ -355,6 +355,55 @@ bool Avatar::findSpherePenetration(const glm::vec3& penetratorCenter, float pene
     return false;
 }
 
+bool Avatar::findSphereCollision(const glm::vec3& sphereCenter, float sphereRadius, CollisionInfo& collision) {
+    // TODO: provide an early exit using bounding sphere of entire avatar
+
+    const HandData* handData = getHandData();
+    if (handData) {
+        int jointIndices[2] = { _skeletonModel.getLeftHandJointIndex(), _skeletonModel.getRightHandJointIndex() };
+        for (int i = 0; i < 2; i++) {
+            const PalmData* palm = handData->getPalm(i);
+            if (palm) {
+                // create a disk collision proxy where the hand is
+                glm::vec3 fingerAxis(0.f);
+                for (size_t f = 0; f < palm->getNumFingers(); ++f) {
+                    const FingerData& finger = (palm->getFingers())[f];
+                    if (finger.isActive()) {
+                        // compute finger axis
+                        glm::vec3 fingerTip = finger.getTipPosition();
+                        glm::vec3 fingerRoot = finger.getRootPosition();
+                        fingerAxis = glm::normalize(fingerTip - fingerRoot);
+                        break;
+                    }
+                }
+                glm::vec3 handPosition;
+                if (i == 0) {
+                    _skeletonModel.getLeftHandPosition(handPosition);
+                }
+                else {
+                    _skeletonModel.getRightHandPosition(handPosition);
+                }
+                glm::vec3 diskCenter = handPosition + HAND_PADDLE_OFFSET * fingerAxis;
+                glm::vec3 diskNormal = palm->getNormal();
+
+                // collide against the disk
+                if (findSphereDiskPenetration(sphereCenter, sphereRadius, 
+                            diskCenter, HAND_PADDLE_RADIUS, diskNormal, collision._penetration)) {
+                    collision._addedVelocity = palm->getVelocity();
+                    return true;
+                }
+            }
+        }
+    }
+
+    if (_skeletonModel.findSpherePenetration(sphereCenter, sphereRadius, collision._penetration)) {
+        collision._penetration /= (float)(TREE_SCALE);
+        collision._addedVelocity = getVelocity();
+        return true;
+    }
+    return false;
+}
+
 int Avatar::parseData(unsigned char* sourceBuffer, int numBytes) {
     // change in position implies movement
     glm::vec3 oldPosition = _position;
diff --git a/interface/src/avatar/Avatar.h b/interface/src/avatar/Avatar.h
index 91f5e75ffc..e02931d2ec 100755
--- a/interface/src/avatar/Avatar.h
+++ b/interface/src/avatar/Avatar.h
@@ -167,6 +167,13 @@ public:
     bool findSpherePenetration(const glm::vec3& penetratorCenter, float penetratorRadius,
         glm::vec3& penetration, int skeletonSkipIndex = -1) const;
 
+    /// Checks for collision between the a sphere and the avatar.
+    /// \param collisionCenter the center of the penetration test sphere
+    /// \param collisionRadius the radius of the penetration test sphere
+    /// \param collision[out] the details of the collision point
+    /// \return whether or not the sphere collided
+    virtual bool findSphereCollision(const glm::vec3& sphereCenter, float sphereRadius, CollisionInfo& collision);
+
     virtual int parseData(unsigned char* sourceBuffer, int numBytes);
 
     static void renderJointConnectingCone(glm::vec3 position1, glm::vec3 position2, float radius1, float radius2);
diff --git a/interface/src/avatar/Hand.cpp b/interface/src/avatar/Hand.cpp
index 2784e0a115..b56e2c0c3d 100644
--- a/interface/src/avatar/Hand.cpp
+++ b/interface/src/avatar/Hand.cpp
@@ -616,23 +616,37 @@ void Hand::renderLeapHands(bool isMine) {
         }
     }
 
-    // Draw the palms
-    for (size_t i = 0; i < getNumPalms(); ++i) {
-        PalmData& palm = getPalms()[i];
-        if (palm.isActive()) {
-            const float palmThickness = 0.02f;
-            if (palm.getIsCollidingWithPalm()) {
-                glColor4f(1, 0, 0, 0.50);
-            } else {
-                glColor4f(handColor.r, handColor.g, handColor.b, 0.25);
+    // Draw the hand paddles
+    int MAX_NUM_PADDLES = 2; // one for left and one for right
+    glColor4f(handColor.r, handColor.g, handColor.b, 0.3f);
+    for (int i = 0; i < MAX_NUM_PADDLES; i++) {
+        const PalmData* palm = getPalm(i);
+        if (palm) {
+            // compute finger axis
+            glm::vec3 fingerAxis(0.f);
+            for (size_t f = 0; f < palm->getNumFingers(); ++f) {
+                const FingerData& finger = (palm->getFingers())[f];
+                if (finger.isActive()) {
+                    glm::vec3 fingerTip = finger.getTipPosition();
+                    glm::vec3 fingerRoot = finger.getRootPosition();
+                    fingerAxis = glm::normalize(fingerTip - fingerRoot);
+                    break;
+                }
             }
-            glm::vec3 tip = palm.getPosition();
-            glm::vec3 root = palm.getPosition() + palm.getNormal() * palmThickness;
-            const float radiusA = 0.05f;
-            const float radiusB = 0.03f;
-            Avatar::renderJointConnectingCone(root, tip, radiusA, radiusB);
+            // compute paddle position
+            glm::vec3 handPosition;
+            if (i == SIXENSE_CONTROLLER_ID_LEFT_HAND) {
+                _owningAvatar->getSkeletonModel().getLeftHandPosition(handPosition);
+            } else if (i == SIXENSE_CONTROLLER_ID_RIGHT_HAND) {
+                _owningAvatar->getSkeletonModel().getRightHandPosition(handPosition);
+            }
+            glm::vec3 tip = handPosition + HAND_PADDLE_OFFSET * fingerAxis;
+            glm::vec3 root = tip + palm->getNormal() * HAND_PADDLE_THICKNESS;
+            // render a very shallow cone as the paddle
+            Avatar::renderJointConnectingCone(root, tip, HAND_PADDLE_RADIUS, 0.f);
         }
     }
+
     glDepthMask(GL_TRUE);
     glEnable(GL_DEPTH_TEST);
 
diff --git a/interface/src/avatar/Hand.h b/interface/src/avatar/Hand.h
index 8a672fc1d9..bc671d1926 100755
--- a/interface/src/avatar/Hand.h
+++ b/interface/src/avatar/Hand.h
@@ -30,6 +30,10 @@
 class Avatar;
 class ProgramObject;
 
+const float HAND_PADDLE_OFFSET = 0.1f;
+const float HAND_PADDLE_THICKNESS = 0.05f;
+const float HAND_PADDLE_RADIUS = 0.15f;
+
 class Hand : public HandData {
 public:
     Hand(Avatar* owningAvatar);
diff --git a/interface/src/avatar/SkeletonModel.cpp b/interface/src/avatar/SkeletonModel.cpp
index 1cfdfbca88..c8fa1e3f14 100644
--- a/interface/src/avatar/SkeletonModel.cpp
+++ b/interface/src/avatar/SkeletonModel.cpp
@@ -8,6 +8,8 @@
 
 #include <glm/gtx/transform.hpp>
 
+#include <HandData.h>
+
 #include "Application.h"
 #include "Avatar.h"
 #include "Menu.h"
diff --git a/interface/src/avatar/SkeletonModel.h b/interface/src/avatar/SkeletonModel.h
index 776eb29e3b..e5ca5c7623 100644
--- a/interface/src/avatar/SkeletonModel.h
+++ b/interface/src/avatar/SkeletonModel.h
@@ -9,7 +9,6 @@
 #ifndef __interface__SkeletonModel__
 #define __interface__SkeletonModel__
 
-#include <HandData.h>
 
 #include "renderer/Model.h"
 
diff --git a/interface/src/renderer/Model.cpp b/interface/src/renderer/Model.cpp
index 3eb1256f0f..3509357b0c 100644
--- a/interface/src/renderer/Model.cpp
+++ b/interface/src/renderer/Model.cpp
@@ -488,6 +488,22 @@ bool Model::getEyePositions(glm::vec3& firstEyePosition, glm::vec3& secondEyePos
     return getJointPosition(geometry.leftEyeJointIndex, firstEyePosition) &&
         getJointPosition(geometry.rightEyeJointIndex, secondEyePosition);
 }
+    
+bool Model::getLeftHandPosition(glm::vec3& position) const {
+    return getJointPosition(getLeftHandJointIndex(), position);
+}
+
+bool Model::getLeftHandRotation(glm::quat& rotation) const {
+    return getJointRotation(getLeftHandJointIndex(), rotation);
+}
+
+bool Model::getRightHandPosition(glm::vec3& position) const {
+    return getJointPosition(getRightHandJointIndex(), position);
+}
+
+bool Model::getRightHandRotation(glm::quat& rotation) const {
+    return getJointRotation(getRightHandJointIndex(), rotation);
+}
 
 bool Model::setLeftHandPosition(const glm::vec3& position) {
     return setJointPosition(getLeftHandJointIndex(), position);
diff --git a/interface/src/renderer/Model.h b/interface/src/renderer/Model.h
index fc3a0687b8..ae4303caea 100644
--- a/interface/src/renderer/Model.h
+++ b/interface/src/renderer/Model.h
@@ -82,6 +82,22 @@ public:
     /// \return whether or not both eye meshes were found
     bool getEyePositions(glm::vec3& firstEyePosition, glm::vec3& secondEyePosition) const;
     
+    /// Retrieve the position of the left hand
+    /// \return true whether or not the position was found
+    bool getLeftHandPosition(glm::vec3& position) const;
+    
+    /// Retrieve the rotation of the left hand
+    /// \return true whether or not the rotation was found
+    bool getLeftHandRotation(glm::quat& rotation) const;
+    
+    /// Retrieve the position of the right hand
+    /// \return true whether or not the position was found
+    bool getRightHandPosition(glm::vec3& position) const;
+    
+    /// Retrieve the rotation of the right hand
+    /// \return true whether or not the rotation was found
+    bool getRightHandRotation(glm::quat& rotation) const;
+    
     /// Sets the position of the left hand using inverse kinematics.
     /// \return whether or not the left hand joint was found
     bool setLeftHandPosition(const glm::vec3& position);
diff --git a/libraries/avatars/src/AvatarData.h b/libraries/avatars/src/AvatarData.h
index c417bfb534..daf299380b 100755
--- a/libraries/avatars/src/AvatarData.h
+++ b/libraries/avatars/src/AvatarData.h
@@ -20,9 +20,10 @@
 #include <QtCore/QUuid>
 #include <QtCore/QVariantMap>
 
+#include <CollisionInfo.h>
 #include <RegisteredMetaTypes.h>
-
 #include <NodeData.h>
+
 #include "HeadData.h"
 #include "HandData.h"
 
@@ -118,6 +119,10 @@ public:
     /// \return whether or not the sphere penetrated
     virtual bool findSpherePenetration(const glm::vec3& penetratorCenter, float penetratorRadius,
         glm::vec3& penetration, int skeletonSkipIndex = -1) const { return false; }
+
+    virtual bool findSphereCollision(const glm::vec3& sphereCenter, float sphereRadius, CollisionInfo& collision) {
+        return false;
+    }
     
 protected:
     QUuid _uuid;
diff --git a/libraries/avatars/src/HandData.cpp b/libraries/avatars/src/HandData.cpp
index e8b2c97ff0..7b0be95abe 100644
--- a/libraries/avatars/src/HandData.cpp
+++ b/libraries/avatars/src/HandData.cpp
@@ -38,8 +38,17 @@ PalmData& HandData::addNewPalm()  {
     return _palms.back();
 }
 
-const int SIXENSE_CONTROLLER_ID_LEFT_HAND = 0;
-const int SIXENSE_CONTROLLER_ID_RIGHT_HAND = 1;
+const PalmData* HandData::getPalm(int sixSenseID) const {
+    // the palms are not necessarily added in left-right order, 
+    // so we have to search for the right SixSenseID
+    for (int i = 0; i < _palms.size(); i++) {
+        const PalmData* palm = &(_palms[i]);
+        if (palm->getSixenseID() == sixSenseID) {
+            return palm->isActive() ? palm : NULL;
+        }
+    }
+    return NULL;
+}
 
 void HandData::getLeftRightPalmIndices(int& leftPalmIndex, int& rightPalmIndex) const {
     leftPalmIndex = -1;
diff --git a/libraries/avatars/src/HandData.h b/libraries/avatars/src/HandData.h
index a0c8fed980..1aa60da927 100755
--- a/libraries/avatars/src/HandData.h
+++ b/libraries/avatars/src/HandData.h
@@ -35,6 +35,9 @@ const int BUTTON_FWD = 128;
 
 const float LEAP_UNIT_SCALE = 0.001f; ///< convert mm to meters
 
+const int SIXENSE_CONTROLLER_ID_LEFT_HAND = 0;
+const int SIXENSE_CONTROLLER_ID_RIGHT_HAND = 1;
+
 class HandData {
 public:
     HandData(AvatarData* owningAvatar);
@@ -55,6 +58,7 @@ public:
 
     std::vector<PalmData>& getPalms() { return _palms; }
     const std::vector<PalmData>& getPalms() const { return _palms; }
+    const PalmData* getPalm(int sixSenseID) const;
     size_t getNumPalms() const { return _palms.size(); }
     PalmData& addNewPalm();
 
diff --git a/libraries/particles/src/ParticleCollisionSystem.cpp b/libraries/particles/src/ParticleCollisionSystem.cpp
index 0bf5db90f0..78b1402461 100644
--- a/libraries/particles/src/ParticleCollisionSystem.cpp
+++ b/libraries/particles/src/ParticleCollisionSystem.cpp
@@ -10,6 +10,7 @@
 #include <AbstractAudioInterface.h>
 #include <VoxelTree.h>
 #include <AvatarData.h>
+#include <CollisionInfo.h>
 #include <HeadData.h>
 #include <HandData.h>
 
@@ -136,15 +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;
@@ -153,77 +153,40 @@ void ParticleCollisionSystem::updateCollisionWithAvatars(Particle* particle) {
     // first check the selfAvatar if set...
     if (_selfAvatar) {
         AvatarData* avatar = (AvatarData*)_selfAvatar;
-        //printf("updateCollisionWithAvatars()..._selfAvatar=%p\n", avatar);
-
-        // check hands...
-        const HandData* handData = avatar->getHandData();
-
-        // TODO: combine hand and collision check into one.  Note: would need to supply
-        // CollisionInfo class rather than just vec3 (penetration) so we can get back
-        // added velocity.
-
-        if (handData->findSpherePenetration(center, radius, penetration, collidingPalm)) {
-            // TODO: dot collidingPalm and hand velocities and skip collision when they are moving apart.
-            // 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)) {
-            // apply hard collision when particle collides with avatar
-            penetration /= (float)(TREE_SCALE);
-            updateCollisionSound(particle, penetration, COLLISION_FREQUENCY);
-            glm::vec3 addedVelocity = avatar->getVelocity();
-            applyHardCollision(particle, penetration, ELASTICITY, DAMPING, addedVelocity);
         }
     }
 
     // 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) {
     //
diff --git a/libraries/particles/src/ParticleCollisionSystem.h b/libraries/particles/src/ParticleCollisionSystem.h
index 920b89c053..13766a0264 100644
--- a/libraries/particles/src/ParticleCollisionSystem.h
+++ b/libraries/particles/src/ParticleCollisionSystem.h
@@ -61,4 +61,4 @@ private:
     AvatarData* _selfAvatar;
 };
 
-#endif /* defined(__hifi__ParticleCollisionSystem__) */
\ No newline at end of file
+#endif /* defined(__hifi__ParticleCollisionSystem__) */
diff --git a/libraries/shared/src/CollisionInfo.h b/libraries/shared/src/CollisionInfo.h
new file mode 100644
index 0000000000..4f46a6bfd3
--- /dev/null
+++ b/libraries/shared/src/CollisionInfo.h
@@ -0,0 +1,26 @@
+//
+//  CollisionInfo.h
+//  hifi
+//
+//  Created by Andrew Meadows on 2014.01.13
+//  Copyright (c) 2014 High Fidelity, Inc. All rights reserved.
+//
+
+#ifndef __hifi__CollisionInfo__
+#define __hifi__CollisionInfo__
+
+#include <glm/glm.hpp>
+
+class CollisionInfo {
+public:
+    CollisionInfo() : _penetration(0.f), _addedVelocity(0.f) { }
+    ~CollisionInfo() {}
+
+    //glm::vec3 _point;
+    //glm::vec3 _normal;
+    glm::vec3 _penetration;
+    glm::vec3 _addedVelocity;
+};
+
+
+#endif /* defined(__hifi__CollisionInfo__) */
diff --git a/libraries/shared/src/GeometryUtil.cpp b/libraries/shared/src/GeometryUtil.cpp
index 5d6e216ad5..2627a9035a 100644
--- a/libraries/shared/src/GeometryUtil.cpp
+++ b/libraries/shared/src/GeometryUtil.cpp
@@ -114,6 +114,30 @@ bool findSpherePlanePenetration(const glm::vec3& sphereCenter, float sphereRadiu
     return false;
 }
 
+bool findSphereDiskPenetration(const glm::vec3& sphereCenter, float sphereRadius, 
+                               const glm::vec3& diskCenter, float diskRadius, const glm::vec3& diskNormal, 
+                               glm::vec3& penetration) {
+    glm::vec3 localCenter = sphereCenter - diskCenter;
+    float verticalDistance = glm::dot(localCenter, diskNormal);
+
+
+    if (abs(verticalDistance) < sphereRadius) {
+        // sphere hit the plane, but does it hit the disk?
+        // Note: this algorithm ignores edge hits.
+        glm::vec3 verticalOffset = verticalDistance * diskNormal;
+        if (glm::length(localCenter - verticalOffset) < diskRadius) {
+            // yes, hit the disk
+            penetration = (sphereRadius - abs(verticalDistance)) * diskNormal;
+            if (verticalDistance < 0.f) {
+                // hit the backside of the disk, so negate penetration vector
+                penetration *= -1.f;
+            }
+            return true;
+        }
+    }
+    return false;
+}
+
 bool findCapsuleSpherePenetration(const glm::vec3& capsuleStart, const glm::vec3& capsuleEnd, float capsuleRadius,
                                   const glm::vec3& sphereCenter, float sphereRadius, glm::vec3& penetration) {
     if (findSphereCapsulePenetration(sphereCenter, sphereRadius,
diff --git a/libraries/shared/src/GeometryUtil.h b/libraries/shared/src/GeometryUtil.h
index 2b782b43ae..59ad055445 100644
--- a/libraries/shared/src/GeometryUtil.h
+++ b/libraries/shared/src/GeometryUtil.h
@@ -47,6 +47,17 @@ bool findSphereCapsuleConePenetration(const glm::vec3& sphereCenter, float spher
 bool findSpherePlanePenetration(const glm::vec3& sphereCenter, float sphereRadius, 
                                 const glm::vec4& plane, glm::vec3& penetration);
                                   
+/// Computes the penetration between a sphere and a disk.
+/// \param sphereCenter center of sphere
+/// \param sphereRadius radius of sphere
+/// \param diskCenter center of disk
+/// \param diskRadius radius of disk
+/// \param diskNormal normal of disk plan
+/// \return true if sphere touches disk (does not handle collisions with disk edge)
+bool findSphereDiskPenetration(const glm::vec3& sphereCenter, float sphereRadius, 
+                               const glm::vec3& diskCenter, float diskRadius, const glm::vec3& diskNormal, 
+                               glm::vec3& penetration);
+
 bool findCapsuleSpherePenetration(const glm::vec3& capsuleStart, const glm::vec3& capsuleEnd, float capsuleRadius,
                                   const glm::vec3& sphereCenter, float sphereRadius, glm::vec3& penetration);