a8ec916af0
Please see HfFluidDemo.cpp for examples of how to use the height field fluid along with buoyant collision shapes. The implementation is still lacking in my ways: 1) Need to complete more collision algorithms for buoyant collision shapes 2) Support compound buoyant shapes 3) The buoyancy model isn't that great 4) Fluid volume can be lost over time
117 lines
5.0 KiB
C++
117 lines
5.0 KiB
C++
#include <stdio.h>
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#include "btHfFluidRigidCollisionAlgorithm.h"
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#include "btHfFluidBuoyantConvexShape.h"
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#include "BulletCollision/CollisionDispatch/btCollisionDispatcher.h"
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#include "BulletCollision/CollisionShapes/btSphereShape.h"
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#include "BulletCollision/CollisionShapes/btBoxShape.h"
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#include "BulletCollision/CollisionDispatch/btCollisionObject.h"
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#include "BulletDynamics/Dynamics/btRigidBody.h"
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#include "btHfFluid.h"
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btHfFluidRigidCollisionAlgorithm::~btHfFluidRigidCollisionAlgorithm()
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{
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}
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btHfFluidRigidCollisionAlgorithm::btHfFluidRigidCollisionAlgorithm(const btCollisionAlgorithmConstructionInfo& ci,btCollisionObject* col0,btCollisionObject* col1, bool isSwapped)
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: btCollisionAlgorithm(ci), m_isSwapped(isSwapped),
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m_convexTrianglecallback(ci.m_dispatcher1, col0, col1, !isSwapped) // we flip the isSwapped because we are hf fluid vs. convex and callback expects convex vs. concave
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{
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m_manifoldPtr = m_convexTrianglecallback.m_manifoldPtr;
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if (m_isSwapped)
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{
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m_hfFluid = static_cast<btHfFluid*>(col1);
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m_rigidCollisionObject = static_cast<btCollisionObject*>(col0);
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m_manifoldPtr->setBodies(m_hfFluid,m_rigidCollisionObject);
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} else {
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m_hfFluid = static_cast<btHfFluid*>(col0);
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m_rigidCollisionObject = static_cast<btCollisionObject*>(col1);
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m_manifoldPtr->setBodies(m_rigidCollisionObject,m_hfFluid);
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}
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}
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void btHfFluidRigidCollisionAlgorithm::processGround (const btDispatcherInfo& dispatchInfo,btManifoldResult* resultOut)
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{
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btScalar triangleMargin = m_rigidCollisionObject->getCollisionShape()->getMargin();
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resultOut->setPersistentManifold(m_manifoldPtr);
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// to perform the convex shape vs. ground terrain:
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// we pull the convex shape out of the buoyant shape and replace it temporarily
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btHfFluidBuoyantConvexShape* tmpShape = (btHfFluidBuoyantConvexShape*)m_rigidCollisionObject->getCollisionShape();
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btConvexShape* convexShape = ((btHfFluidBuoyantConvexShape*)tmpShape)->getConvexShape();
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m_rigidCollisionObject->setCollisionShape (convexShape);
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m_convexTrianglecallback.setTimeStepAndCounters (triangleMargin, dispatchInfo, resultOut);
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m_hfFluid->foreachGroundTriangle (&m_convexTrianglecallback, m_convexTrianglecallback.getAabbMin(),m_convexTrianglecallback.getAabbMax());
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resultOut->refreshContactPoints();
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// restore the buoyant shape
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m_rigidCollisionObject->setCollisionShape (tmpShape);
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}
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btScalar btHfFluidRigidCollisionAlgorithm::processFluid (const btDispatcherInfo& dispatchInfo, btScalar density, btScalar floatyness)
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{
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btRigidBody* rb = btRigidBody::upcast(m_rigidCollisionObject);
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btHfFluidColumnRigidBodyCallback columnCallback (rb, dispatchInfo.m_debugDraw, density, floatyness);
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m_hfFluid->foreachFluidColumn (&columnCallback, m_convexTrianglecallback.getAabbMin(), m_convexTrianglecallback.getAabbMax());
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return columnCallback.getVolume ();
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}
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void btHfFluidRigidCollisionAlgorithm::applyFluidFriction (btScalar mu, btScalar submerged_percentage)
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{
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btRigidBody* rb = btRigidBody::upcast(m_rigidCollisionObject);
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btScalar dt = btScalar(1.0f/60.0f);
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//#define OLD_WAY
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#ifdef OLD_WAY
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btScalar radius = btScalar(0.0f);
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{
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btVector3 aabbMin, aabbMax;
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btTransform T;
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T.setIdentity();
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rb->getCollisionShape()->getAabb (T, aabbMin, aabbMax);
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radius = (aabbMax-aabbMin).length()*btScalar(0.5);
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}
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btScalar viscosity = btScalar(0.05);
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btVector3 force = btScalar(6.0f) * SIMD_PI * viscosity * radius * -rb->getLinearVelocity();
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btVector3 impulse = force * dt;
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rb->applyCentralImpulse (impulse);
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if (true)
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{
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btVector3 av = rb->getAngularVelocity();
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av *= btScalar(0.99);
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rb->setAngularVelocity (av);
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}
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#else
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btScalar scaled_mu = mu * submerged_percentage * btScalar(0.4f);
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rb->applyCentralImpulse (dt * scaled_mu * -rb->getLinearVelocity());
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rb->applyTorqueImpulse (dt * scaled_mu * -rb->getAngularVelocity());
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#endif
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}
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void btHfFluidRigidCollisionAlgorithm::processCollision (btCollisionObject* body0,btCollisionObject* body1,const btDispatcherInfo& dispatchInfo,btManifoldResult* resultOut)
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{
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processGround (dispatchInfo, resultOut);
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btHfFluidBuoyantConvexShape* buoyantShape = (btHfFluidBuoyantConvexShape*)m_rigidCollisionObject->getCollisionShape();
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btRigidBody* rb = btRigidBody::upcast(m_rigidCollisionObject);
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if (rb)
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{
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btScalar mass = btScalar(1.0f) / rb->getInvMass ();
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btScalar volume = buoyantShape->getTotalVolume ();
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btScalar density = mass / volume;
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btScalar floatyness = buoyantShape->getFloatyness ();
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btScalar submerged_volume = processFluid (dispatchInfo, density, floatyness);
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if (submerged_volume > btScalar(0.0))
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{
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btScalar submerged_percentage = submerged_volume/buoyantShape->getTotalVolume();
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//printf("%f\n", submerged_percentage);
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btScalar mu = btScalar(6.0f);
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applyFluidFriction (mu, submerged_percentage);
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}
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}
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}
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btScalar btHfFluidRigidCollisionAlgorithm::calculateTimeOfImpact(btCollisionObject* body0,btCollisionObject* body1,const btDispatcherInfo& dispatchInfo,btManifoldResult* resultOut)
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{
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return btScalar(1.0);
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}
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