From 98d27ad2b53656da0f2b38761f6720d2a0dc45df Mon Sep 17 00:00:00 2001
From: Andrew Meadows <andrew@highfidelity.io>
Date: Thu, 14 Aug 2014 15:17:03 -0700
Subject: [PATCH] more correct names for ContactPoint API

renamed (and disabled) the useless enforce() to applyFriction()
changed the buildConstraints() method to more correct name: enforce()
will eventually change how ContactPoint actually works, but later
---
 libraries/shared/src/ContactPoint.cpp      | 39 ++++++++++++----------
 libraries/shared/src/ContactPoint.h        |  4 +--
 libraries/shared/src/PhysicsSimulation.cpp | 24 ++++++-------
 libraries/shared/src/PhysicsSimulation.h   |  4 +--
 4 files changed, 37 insertions(+), 34 deletions(-)

diff --git a/libraries/shared/src/ContactPoint.cpp b/libraries/shared/src/ContactPoint.cpp
index 4c1cf7b842..4f1cf87da5 100644
--- a/libraries/shared/src/ContactPoint.cpp
+++ b/libraries/shared/src/ContactPoint.cpp
@@ -88,25 +88,7 @@ ContactPoint::ContactPoint(const CollisionInfo& collision, quint32 frame) :
     }
 }
 
-// virtual 
 float ContactPoint::enforce() {
-    for (int i = 0; i < _numPoints; ++i) {
-        glm::vec3& position = _points[i]->_position;
-        // TODO: use a fast distance approximation
-        float newDistance = glm::distance(_contactPoint, position);
-        float constrainedDistance = _distances[i];
-        // NOTE: these "distance" constraints only push OUT, don't pull IN.
-        if (newDistance > EPSILON && newDistance < constrainedDistance) {
-            glm::vec3 direction = (_contactPoint - position) / newDistance;
-            glm::vec3 center = 0.5f * (_contactPoint + position);
-            _contactPoint = center + (0.5f * constrainedDistance) * direction;
-            position = center - (0.5f * constrainedDistance) * direction;
-        }
-    }
-    return 0.0f;
-}
-
-void ContactPoint::buildConstraints() {
     glm::vec3 pointA = _shapeA->getTranslation() + _offsetA;
     glm::vec3 pointB = _shapeB->getTranslation() + _offsetB;
     glm::vec3 penetration = pointA - pointB;
@@ -153,6 +135,27 @@ void ContactPoint::buildConstraints() {
             _distances[i] = glm::length(glm::length(_offsets[i]));
         }
     }
+    return 0.0f;
+}
+
+// virtual 
+void ContactPoint::applyFriction() {
+    // TODO: Andrew to re-implement this
+    /*
+    for (int i = 0; i < _numPoints; ++i) {
+        glm::vec3& position = _points[i]->_position;
+        // TODO: use a fast distance approximation
+        float newDistance = glm::distance(_contactPoint, position);
+        float constrainedDistance = _distances[i];
+        // NOTE: these "distance" constraints only push OUT, don't pull IN.
+        if (newDistance > EPSILON && newDistance < constrainedDistance) {
+            glm::vec3 direction = (_contactPoint - position) / newDistance;
+            glm::vec3 center = 0.5f * (_contactPoint + position);
+            _contactPoint = center + (0.5f * constrainedDistance) * direction;
+            position = center - (0.5f * constrainedDistance) * direction;
+        }
+    }
+    */
 }
 
 void ContactPoint::updateContact(const CollisionInfo& collision, quint32 frame) {
diff --git a/libraries/shared/src/ContactPoint.h b/libraries/shared/src/ContactPoint.h
index 5257fabee0..d584945970 100644
--- a/libraries/shared/src/ContactPoint.h
+++ b/libraries/shared/src/ContactPoint.h
@@ -26,8 +26,8 @@ public:
     ContactPoint(const CollisionInfo& collision, quint32 frame);
 
     virtual float enforce();
-   
-    void buildConstraints();
+
+    void applyFriction();
     void updateContact(const CollisionInfo& collision, quint32 frame);
     quint32 getLastFrame() const { return _lastFrame; }
 
diff --git a/libraries/shared/src/PhysicsSimulation.cpp b/libraries/shared/src/PhysicsSimulation.cpp
index 84f8282c9d..a62b3816af 100644
--- a/libraries/shared/src/PhysicsSimulation.cpp
+++ b/libraries/shared/src/PhysicsSimulation.cpp
@@ -195,7 +195,7 @@ void PhysicsSimulation::stepForward(float deltaTime, float minError, int maxIter
     quint64 expiry = startTime + maxUsec;
 
     moveRagdolls(deltaTime);
-    buildContactConstraints();
+    enforceContacts();
     int numDolls = _otherRagdolls.size();
     {
         PerformanceTimer perfTimer("enforce");
@@ -219,7 +219,7 @@ void PhysicsSimulation::stepForward(float deltaTime, float minError, int maxIter
                 error = glm::max(error, _otherRagdolls[i]->enforceConstraints());
             }
         }
-        enforceContactConstraints();
+        applyContactFriction();
         ++iterations;
 
         now = usecTimestampNow();
@@ -288,16 +288,7 @@ void PhysicsSimulation::resolveCollisions() {
     }
 }
 
-void PhysicsSimulation::buildContactConstraints() {
-    PerformanceTimer perfTimer("contacts");
-    QMap<quint64, ContactPoint>::iterator itr = _contacts.begin();
-    while (itr != _contacts.end()) {
-        itr.value().buildConstraints();
-        ++itr;
-    }
-}
-
-void PhysicsSimulation::enforceContactConstraints() {
+void PhysicsSimulation::enforceContacts() {
     PerformanceTimer perfTimer("contacts");
     QMap<quint64, ContactPoint>::iterator itr = _contacts.begin();
     while (itr != _contacts.end()) {
@@ -306,6 +297,15 @@ void PhysicsSimulation::enforceContactConstraints() {
     }
 }
 
+void PhysicsSimulation::applyContactFriction() {
+    PerformanceTimer perfTimer("contacts");
+    QMap<quint64, ContactPoint>::iterator itr = _contacts.begin();
+    while (itr != _contacts.end()) {
+        itr.value().applyFriction();
+        ++itr;
+    }
+}
+
 void PhysicsSimulation::updateContacts() {
     PerformanceTimer perfTimer("contacts");
     int numCollisions = _collisions.size();
diff --git a/libraries/shared/src/PhysicsSimulation.h b/libraries/shared/src/PhysicsSimulation.h
index 61ab1bf177..881007208b 100644
--- a/libraries/shared/src/PhysicsSimulation.h
+++ b/libraries/shared/src/PhysicsSimulation.h
@@ -56,8 +56,8 @@ protected:
     void computeCollisions();
     void resolveCollisions();
 
-    void buildContactConstraints();
-    void enforceContactConstraints();
+    void enforceContacts();
+    void applyContactFriction();
     void updateContacts();
     void pruneContacts();