Merge pull request #6292 from huffman/physics-continuous-collision-detection

Physics continuous collision detection

cmake/externals/bullet/CMakeLists.txt

@@ -18,8 +18,8 @@ if (WIN32)
   ExternalProject_Add(
     ${EXTERNAL_NAME}
     # URL https://bullet.googlecode.com/files/bullet-2.82-r2704.zip
-    URL http://hifi-public.s3.amazonaws.com/dependencies/bullet-2.82-r2704.zip
-    URL_MD5 f5e8914fc9064ad32e0d62d19d33d977
+    URL http://hifi-public.s3.amazonaws.com/dependencies/bullet-2.82-ccd-fix.zip
+    URL_MD5 d95b07eb120de7dd7786361c0b5a8d9f
     CMAKE_ARGS ${PLATFORM_CMAKE_ARGS} -DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR> -DBUILD_EXTRAS=0 -DINSTALL_LIBS=1 -DBUILD_DEMOS=0 -DUSE_GLUT=0 -DUSE_DX11=0
     LOG_DOWNLOAD 1
     LOG_CONFIGURE 1
@@ -30,8 +30,8 @@ else ()
   ExternalProject_Add(
     ${EXTERNAL_NAME}
     #URL http://bullet.googlecode.com/files/bullet-2.82-r2704.tgz
-    URL http://hifi-public.s3.amazonaws.com/dependencies/bullet-2.82-r2704.tgz
-    URL_MD5 70b3c8d202dee91a0854b4cbc88173e8
+    URL http://hifi-public.s3.amazonaws.com/dependencies/bullet-2.82-ccd-fix.tgz
+    URL_MD5 fb140a4983b4109aa1c825a162aa8d64
     CMAKE_ARGS ${PLATFORM_CMAKE_ARGS} -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_INSTALL_PREFIX:PATH=<INSTALL_DIR> -DBUILD_EXTRAS=0 -DINSTALL_LIBS=1 -DBUILD_DEMOS=0 -DUSE_GLUT=0
     LOG_DOWNLOAD 1
     LOG_CONFIGURE 1
@@ -80,4 +80,4 @@ endif ()
 
 if (DEFINED ${EXTERNAL_NAME_UPPER}_DYNAMICS_LIBRARY_RELEASE)
   set(${EXTERNAL_NAME_UPPER}_INCLUDE_DIR ${INSTALL_DIR}/include/bullet CACHE PATH "Path to bullet include directory")
-endif ()
+endif ()

libraries/physics/src/ObjectMotionState.cpp

@@ -123,6 +123,31 @@ void ObjectMotionState::setMotionType(MotionType motionType) {
     _motionType = motionType;
 }
 
+// Update the Continuous Collision Detection (CCD) configuration settings of our RigidBody so that
+// CCD will be enabled automatically when its speed surpasses a certain threshold.
+void ObjectMotionState::updateCCDConfiguration() {
+    if (_body) {
+        if (_shape) {
+            // If this object moves faster than its bounding radius * RADIUS_MOTION_THRESHOLD_MULTIPLIER,
+            // CCD will be enabled for this object.
+            const auto RADIUS_MOTION_THRESHOLD_MULTIPLIER = 0.5f;
+
+            btVector3 center;
+            btScalar radius;
+            _shape->getBoundingSphere(center, radius);
+            _body->setCcdMotionThreshold(radius * RADIUS_MOTION_THRESHOLD_MULTIPLIER);
+
+            // TODO: Ideally the swept sphere radius would be contained by the object. Using the bounding sphere
+            // radius works well for spherical objects, but may cause issues with other shapes. For arbitrary
+            // objects we may want to consider a different approach, such as grouping rigid bodies together.
+            _body->setCcdSweptSphereRadius(radius);
+        } else {
+            // Disable CCD
+            _body->setCcdMotionThreshold(0);
+        }
+    }
+}
+
 void ObjectMotionState::setRigidBody(btRigidBody* body) {
     // give the body a (void*) back-pointer to this ObjectMotionState
     if (_body != body) {
@@ -133,6 +158,7 @@ void ObjectMotionState::setRigidBody(btRigidBody* body) {
         if (_body) {
             _body->setUserPointer(this);
         }
+        updateCCDConfiguration();
     }
 }
 
@@ -232,6 +258,8 @@ bool ObjectMotionState::handleHardAndEasyChanges(uint32_t& flags, PhysicsEngine*
         if (_shape != newShape) {
             _shape = newShape;
             _body->setCollisionShape(_shape);
+
+            updateCCDConfiguration();
         } else {
             // huh... the shape didn't actually change, so we clear the DIRTY_SHAPE flag
             flags &= ~Simulation::DIRTY_SHAPE;

libraries/physics/src/ObjectMotionState.h

@@ -151,6 +151,7 @@ protected:
     virtual bool isReadyToComputeShape() = 0;
     virtual btCollisionShape* computeNewShape() = 0;
     void setMotionType(MotionType motionType);
+    void updateCCDConfiguration();
 
     // clearObjectBackPointer() overrrides should call the base method, then actually clear the object back pointer.
     virtual void clearObjectBackPointer() { _type = MOTIONSTATE_TYPE_INVALID; }