UPBGE: Fix compound ray cast with triangle child shape.

Previously when a compound shape was hit by a ray cast the information about
the children triangles was inaccessible because of a lack from the bullet
API.

To fix this issue we have to keep the triangle index but add a child index
of the compound child shape hit. m_childIndex is dedicated for in LocalRayResult
and its value is set in rayTestSingleInternal, -1 for non compound shapes.

This value is catch from FilterClosestRayResultCallback and used in RayTest
to get the actual collision shape. To still get the shape construction info
of the children, each collision shape created has as user pointer the
shape costruction info. This object is get in RayTest to find the mesh
and polygon.

Tested with:
- mix of convex and concave shape in a compound shape.
- non compound concave and convex shape.

Author: panzergame

extern/bullet/src/BulletCollision/CollisionDispatch/btCollisionWorld.cpp

@@ -340,8 +340,8 @@ void	btCollisionWorld::rayTestSingleInternal(const btTransform& rayFromTrans,con
 						collisionObjectWrap->getCollisionObject(),
 						0,
 						castResult.m_normal,
-						castResult.m_fraction
-						);
+						castResult.m_fraction,
+						-1);
 
 					bool normalInWorldSpace = true;
 					resultCallback.addSingleResult(localRayResult, normalInWorldSpace);
@@ -386,7 +386,8 @@ void	btCollisionWorld::rayTestSingleInternal(const btTransform& rayFromTrans,con
 							(m_collisionObject,
 							&shapeInfo,
 							hitNormalWorld,
-							hitFraction);
+							hitFraction,
+							-1);
 
 						bool	normalInWorldSpace = true;
 						return m_resultCallback->addSingleResult(rayResult,normalInWorldSpace);
@@ -468,7 +469,8 @@ void	btCollisionWorld::rayTestSingleInternal(const btTransform& rayFromTrans,con
 							(m_collisionObject,
 							&shapeInfo,
 							hitNormalWorld,
-							hitFraction);
+							hitFraction,
+							-1);
 
 						bool	normalInWorldSpace = true;
 						return m_resultCallback->addSingleResult(rayResult,normalInWorldSpace);
@@ -509,11 +511,7 @@ void	btCollisionWorld::rayTestSingleInternal(const btTransform& rayFromTrans,con
 
 					virtual btScalar addSingleResult (btCollisionWorld::LocalRayResult &r, bool b)
 					{
-						btCollisionWorld::LocalShapeInfo shapeInfo;
-						shapeInfo.m_shapePart = -1;
-						shapeInfo.m_triangleIndex = m_i;
-						if (r.m_localShapeInfo == NULL)
-							r.m_localShapeInfo = &shapeInfo;
+						r.m_childIndex = m_i;
 
 						const btScalar result = m_userCallback->addSingleResult(r, b);
 						m_closestHitFraction = m_userCallback->m_closestHitFraction;

extern/bullet/src/BulletCollision/CollisionDispatch/btCollisionWorld.h

@@ -188,19 +188,21 @@ class btCollisionWorld
 		LocalRayResult(const btCollisionObject*	collisionObject, 
 			LocalShapeInfo*	localShapeInfo,
 			const btVector3&		hitNormalLocal,
-			btScalar hitFraction)
+			btScalar hitFraction,
+			int childIndex)
 		:m_collisionObject(collisionObject),
 		m_localShapeInfo(localShapeInfo),
 		m_hitNormalLocal(hitNormalLocal),
-		m_hitFraction(hitFraction)
+		m_hitFraction(hitFraction),
+		m_childIndex(childIndex)
 		{
 		}
 
 		const btCollisionObject*		m_collisionObject;
 		LocalShapeInfo*			m_localShapeInfo;
 		btVector3				m_hitNormalLocal;
 		btScalar				m_hitFraction;
-
+		int m_childIndex;
 	};
 
 	///RayResultCallback is used to report new raycast results

extern/bullet/src/BulletSoftBody/btSoftMultiBodyDynamicsWorld.cpp

@@ -317,7 +317,8 @@ void	btSoftMultiBodyDynamicsWorld::rayTestSingle(const btTransform& rayFromTrans
 						(collisionObject,
 						 &shapeInfo,
 						 normal,
-						 softResult.fraction);
+						 softResult.fraction,
+						 -1);
 					bool	normalInWorldSpace = true;
 					resultCallback.addSingleResult(rayResult,normalInWorldSpace);
 				}

extern/bullet/src/BulletSoftBody/btSoftRigidDynamicsWorld.cpp

@@ -317,7 +317,8 @@ void	btSoftRigidDynamicsWorld::rayTestSingle(const btTransform& rayFromTrans,con
 						(collisionObject,
 						 &shapeInfo,
 						 normal,
-						 softResult.fraction);
+						 softResult.fraction,
+						 -1);
 					bool	normalInWorldSpace = true;
 					resultCallback.addSingleResult(rayResult,normalInWorldSpace);
 				}

extern/bullet/src/BulletSoftBody/btSoftRigidDynamicsWorldMt.cpp

@@ -318,7 +318,8 @@ void	btSoftRigidDynamicsWorldMt::rayTestSingle(const btTransform& rayFromTrans,c
 						(collisionObject,
 						 &shapeInfo,
 						 normal,
-						 softResult.fraction);
+						 softResult.fraction,
+						 -1);
 					bool	normalInWorldSpace = true;
 					resultCallback.addSingleResult(rayResult,normalInWorldSpace);
 				}

source/gameengine/Physics/Bullet/CcdPhysicsController.cpp

@@ -2142,6 +2142,11 @@ btCollisionShape *CcdShapeConstructionInfo::CreateBulletShape(btScalar margin, b
 			BLI_assert(false);
 		}
 	}
+
+	if (collisionShape) {
+		collisionShape->setUserPointer(this);
+	}
+
 	return collisionShape;
 }
 

source/gameengine/Physics/Bullet/CcdPhysicsEnvironment.cpp

@@ -1101,13 +1101,13 @@ void CcdPhysicsEnvironment::RemoveConstraintById(int constraintId, bool free)
 
 struct  FilterClosestRayResultCallback : public btCollisionWorld::ClosestRayResultCallback {
 	PHY_IRayCastFilterCallback& m_phyRayFilter;
-	const btCollisionShape *m_hitTriangleShape;
+	int m_hitChildIndex;
 	int m_hitTriangleIndex;
 
 	FilterClosestRayResultCallback(PHY_IRayCastFilterCallback& phyRayFilter, const btVector3& rayFrom, const btVector3& rayTo)
 		:btCollisionWorld::ClosestRayResultCallback(rayFrom, rayTo),
 		m_phyRayFilter(phyRayFilter),
-		m_hitTriangleShape(nullptr),
+		m_hitChildIndex(-1),
 		m_hitTriangleIndex(0)
 	{
 	}
@@ -1134,21 +1134,18 @@ struct  FilterClosestRayResultCallback : public btCollisionWorld::ClosestRayResu
 
 	virtual btScalar addSingleResult(btCollisionWorld::LocalRayResult& rayResult, bool normalInWorldSpace)
 	{
-		//CcdPhysicsController* curHit = static_cast<CcdPhysicsController*>(rayResult.m_collisionObject->getUserPointer());
-		// save shape information as ClosestRayResultCallback::AddSingleResult() does not do it
+		m_hitChildIndex = rayResult.m_childIndex;
 		if (rayResult.m_localShapeInfo) {
-			m_hitTriangleShape = rayResult.m_collisionObject->getCollisionShape();
 			m_hitTriangleIndex = rayResult.m_localShapeInfo->m_triangleIndex;
 		}
 		else {
-			m_hitTriangleShape = nullptr;
 			m_hitTriangleIndex = 0;
 		}
 		return ClosestRayResultCallback::addSingleResult(rayResult, normalInWorldSpace);
 	}
 };
 
-static bool GetHitTriangle(btCollisionShape *shape, CcdShapeConstructionInfo *shapeInfo, int hitTriangleIndex, btVector3 triangle[])
+static bool GetHitTriangle(const btCollisionShape *shape, CcdShapeConstructionInfo *shapeInfo, int hitTriangleIndex, btVector3 triangle[])
 {
 	// this code is copied from Bullet
 	const unsigned char *vertexbase;
@@ -1198,132 +1195,119 @@ PHY_IPhysicsController *CcdPhysicsEnvironment::RayTest(PHY_IRayCastFilterCallbac
 
 	//Either Ray Cast with or without filtering
 
-	//btCollisionWorld::ClosestRayResultCallback rayCallback(rayFrom,rayTo);
 	FilterClosestRayResultCallback rayCallback(filterCallback, rayFrom, rayTo);
-
 	PHY_RayCastResult result;
 
 	// don't collision with sensor object
 	rayCallback.m_collisionFilterMask = CcdConstructionInfo::AllFilter ^ CcdConstructionInfo::SensorFilter;
 	// use faster (less accurate) ray callback, works better with 0 collision margins
 	rayCallback.m_flags |= btTriangleRaycastCallback::kF_UseSubSimplexConvexCastRaytest;
-	//, ,filterCallback.m_faceNormal);
 
 	m_dynamicsWorld->rayTest(rayFrom, rayTo, rayCallback);
 	if (rayCallback.hasHit()) {
+		const btCollisionObject *object = rayCallback.m_collisionObject;
+		const btCollisionShape *shape = object->getCollisionShape();
+
 		CcdPhysicsController *controller = static_cast<CcdPhysicsController *>(rayCallback.m_collisionObject->getUserPointer());
 		result.m_controller = controller;
-		result.m_hitPoint[0] = rayCallback.m_hitPointWorld.getX();
-		result.m_hitPoint[1] = rayCallback.m_hitPointWorld.getY();
-		result.m_hitPoint[2] = rayCallback.m_hitPointWorld.getZ();
-
-		if (rayCallback.m_hitTriangleShape != nullptr) {
-			// identify the mesh polygon
-			CcdShapeConstructionInfo *shapeInfo = controller->m_shapeInfo;
-			if (shapeInfo) {
-				btCollisionShape *shape = controller->GetCollisionObject()->getCollisionShape();
-				if (shape->isCompound()) {
-					btCompoundShape *compoundShape = (btCompoundShape *)shape;
-					CcdShapeConstructionInfo *compoundShapeInfo = shapeInfo;
-					// need to search which sub-shape has been hit
-					for (int i = 0; i < compoundShape->getNumChildShapes(); i++) {
-						shapeInfo = compoundShapeInfo->GetChildShape(i);
-						shape = compoundShape->getChildShape(i);
-						if (shape == rayCallback.m_hitTriangleShape) {
-							break;
+		result.m_hitPoint = ToMt(rayCallback.m_hitPointWorld);
+
+		if (shape) {
+			if (shape->isCompound()) {
+				const btCompoundShape *compoundShape = static_cast<const btCompoundShape *>(shape);
+				shape = compoundShape->getChildShape(rayCallback.m_hitChildIndex);
+			}
+
+			CcdShapeConstructionInfo *shapeInfo = static_cast<CcdShapeConstructionInfo *>(shape->getUserPointer());
+			if (shapeInfo && rayCallback.m_hitTriangleIndex < shapeInfo->m_polygonIndexArray.size()) {
+				// save original collision shape triangle for soft body
+				const int hitTriangleIndex = rayCallback.m_hitTriangleIndex;
+
+				result.m_meshObject = shapeInfo->GetMesh();
+				if (shape->isSoftBody()) {
+					// soft body using different face numbering because of randomization
+					// hopefully we have stored the original face number in m_tag
+					const btSoftBody *softBody = static_cast<const btSoftBody *>(object);
+					if (softBody->m_faces[hitTriangleIndex].m_tag != 0) {
+						rayCallback.m_hitTriangleIndex = (int)((uintptr_t)(softBody->m_faces[hitTriangleIndex].m_tag) - 1);
+					}
+				}
+				// retrieve the original mesh polygon (in case of quad->tri conversion)
+				result.m_polygon = shapeInfo->m_polygonIndexArray[rayCallback.m_hitTriangleIndex];
+				// hit triangle in world coordinate, for face normal and UV coordinate
+				btVector3 triangle[3];
+				bool triangleOK = false;
+				if (filterCallback.m_faceUV && (3 * rayCallback.m_hitTriangleIndex) < shapeInfo->m_triFaceUVcoArray.size()) {
+					// interpolate the UV coordinate of the hit point
+					CcdShapeConstructionInfo::UVco *uvCo = &shapeInfo->m_triFaceUVcoArray[3 * rayCallback.m_hitTriangleIndex];
+					// 1. get the 3 coordinate of the triangle in world space
+					btVector3 v1, v2, v3;
+					if (shape->isSoftBody()) {
+						// soft body give points directly in world coordinate
+						const btSoftBody *softBody = static_cast<const btSoftBody *>(object);
+						v1 = softBody->m_faces[hitTriangleIndex].m_n[0]->m_x;
+						v2 = softBody->m_faces[hitTriangleIndex].m_n[1]->m_x;
+						v3 = softBody->m_faces[hitTriangleIndex].m_n[2]->m_x;
+					}
+					else {
+						// for rigid body we must apply the world transform
+						triangleOK = GetHitTriangle(shape, shapeInfo, hitTriangleIndex, triangle);
+						if (!triangleOK) {
+							// if we cannot get the triangle, no use to continue
+							goto SKIP_UV_NORMAL;
 						}
+						const btTransform& trans = object->getWorldTransform();
+						v1 = trans(triangle[0]);
+						v2 = trans(triangle[1]);
+						v3 = trans(triangle[2]);
 					}
+					// 2. compute barycentric coordinate of the hit point
+					btVector3 v = v2 - v1;
+					btVector3 w = v3 - v1;
+					btVector3 u = v.cross(w);
+					btScalar A = u.length();
+
+					v = v2 - rayCallback.m_hitPointWorld;
+					w = v3 - rayCallback.m_hitPointWorld;
+					u = v.cross(w);
+					btScalar A1 = u.length();
+
+					v = rayCallback.m_hitPointWorld - v1;
+					w = v3 - v1;
+					u = v.cross(w);
+					btScalar A2 = u.length();
+
+					btVector3 baryCo;
+					baryCo.setX(A1 / A);
+					baryCo.setY(A2 / A);
+					baryCo.setZ(1.0f - baryCo.getX() - baryCo.getY());
+					// 3. compute UV coordinate
+					result.m_hitUV[0] = baryCo.getX() * uvCo[0].uv[0] + baryCo.getY() * uvCo[1].uv[0] + baryCo.getZ() * uvCo[2].uv[0];
+					result.m_hitUV[1] = baryCo.getX() * uvCo[0].uv[1] + baryCo.getY() * uvCo[1].uv[1] + baryCo.getZ() * uvCo[2].uv[1];
+					result.m_hitUVOK = 1;
 				}
-				if (shape == rayCallback.m_hitTriangleShape &&
-				    rayCallback.m_hitTriangleIndex < shapeInfo->m_polygonIndexArray.size()) {
-					// save original collision shape triangle for soft body
-					int hitTriangleIndex = rayCallback.m_hitTriangleIndex;
 
-					result.m_meshObject = shapeInfo->GetMesh();
+				// Bullet returns the normal from "outside".
+				// If the user requests the real normal, compute it now
+				if (filterCallback.m_faceNormal) {
 					if (shape->isSoftBody()) {
-						// soft body using different face numbering because of randomization
-						// hopefully we have stored the original face number in m_tag
+						// we can get the real normal directly from the body
 						const btSoftBody *softBody = static_cast<const btSoftBody *>(rayCallback.m_collisionObject);
-						if (softBody->m_faces[hitTriangleIndex].m_tag != 0) {
-							rayCallback.m_hitTriangleIndex = (int)((uintptr_t)(softBody->m_faces[hitTriangleIndex].m_tag) - 1);
-						}
+						rayCallback.m_hitNormalWorld = softBody->m_faces[hitTriangleIndex].m_normal;
 					}
-					// retrieve the original mesh polygon (in case of quad->tri conversion)
-					result.m_polygon = shapeInfo->m_polygonIndexArray[rayCallback.m_hitTriangleIndex];
-					// hit triangle in world coordinate, for face normal and UV coordinate
-					btVector3 triangle[3];
-					bool triangleOK = false;
-					if (filterCallback.m_faceUV && (3 * rayCallback.m_hitTriangleIndex) < shapeInfo->m_triFaceUVcoArray.size()) {
-						// interpolate the UV coordinate of the hit point
-						CcdShapeConstructionInfo::UVco *uvCo = &shapeInfo->m_triFaceUVcoArray[3 * rayCallback.m_hitTriangleIndex];
-						// 1. get the 3 coordinate of the triangle in world space
-						btVector3 v1, v2, v3;
-						if (shape->isSoftBody()) {
-							// soft body give points directly in world coordinate
-							const btSoftBody *softBody = static_cast<const btSoftBody *>(rayCallback.m_collisionObject);
-							v1 = softBody->m_faces[hitTriangleIndex].m_n[0]->m_x;
-							v2 = softBody->m_faces[hitTriangleIndex].m_n[1]->m_x;
-							v3 = softBody->m_faces[hitTriangleIndex].m_n[2]->m_x;
-						}
-						else {
-							// for rigid body we must apply the world transform
+					else {
+						if (!triangleOK) {
 							triangleOK = GetHitTriangle(shape, shapeInfo, hitTriangleIndex, triangle);
-							if (!triangleOK) {
-								// if we cannot get the triangle, no use to continue
-								goto SKIP_UV_NORMAL;
-							}
-							v1 = rayCallback.m_collisionObject->getWorldTransform()(triangle[0]);
-							v2 = rayCallback.m_collisionObject->getWorldTransform()(triangle[1]);
-							v3 = rayCallback.m_collisionObject->getWorldTransform()(triangle[2]);
 						}
-						// 2. compute barycentric coordinate of the hit point
-						btVector3 v = v2 - v1;
-						btVector3 w = v3 - v1;
-						btVector3 u = v.cross(w);
-						btScalar A = u.length();
-
-						v = v2 - rayCallback.m_hitPointWorld;
-						w = v3 - rayCallback.m_hitPointWorld;
-						u = v.cross(w);
-						btScalar A1 = u.length();
-
-						v = rayCallback.m_hitPointWorld - v1;
-						w = v3 - v1;
-						u = v.cross(w);
-						btScalar A2 = u.length();
-
-						btVector3 baryCo;
-						baryCo.setX(A1 / A);
-						baryCo.setY(A2 / A);
-						baryCo.setZ(1.0f - baryCo.getX() - baryCo.getY());
-						// 3. compute UV coordinate
-						result.m_hitUV[0] = baryCo.getX() * uvCo[0].uv[0] + baryCo.getY() * uvCo[1].uv[0] + baryCo.getZ() * uvCo[2].uv[0];
-						result.m_hitUV[1] = baryCo.getX() * uvCo[0].uv[1] + baryCo.getY() * uvCo[1].uv[1] + baryCo.getZ() * uvCo[2].uv[1];
-						result.m_hitUVOK = 1;
-					}
-
-					// Bullet returns the normal from "outside".
-					// If the user requests the real normal, compute it now
-					if (filterCallback.m_faceNormal) {
-						if (shape->isSoftBody()) {
-							// we can get the real normal directly from the body
-							const btSoftBody *softBody = static_cast<const btSoftBody *>(rayCallback.m_collisionObject);
-							rayCallback.m_hitNormalWorld = softBody->m_faces[hitTriangleIndex].m_normal;
-						}
-						else {
-							if (!triangleOK) {
-								triangleOK = GetHitTriangle(shape, shapeInfo, hitTriangleIndex, triangle);
-							}
-							if (triangleOK) {
-								btVector3 triangleNormal;
-								triangleNormal = (triangle[1] - triangle[0]).cross(triangle[2] - triangle[0]);
-								rayCallback.m_hitNormalWorld = rayCallback.m_collisionObject->getWorldTransform().getBasis() * triangleNormal;
-							}
+						if (triangleOK) {
+							btVector3 triangleNormal;
+							triangleNormal = (triangle[1] - triangle[0]).cross(triangle[2] - triangle[0]);
+							rayCallback.m_hitNormalWorld = rayCallback.m_collisionObject->getWorldTransform().getBasis() * triangleNormal;
 						}
 					}
-SKIP_UV_NORMAL:
-					;
 				}
+SKIP_UV_NORMAL:
+				;
 			}
 		}
 		if (rayCallback.m_hitNormalWorld.length2() > (SIMD_EPSILON * SIMD_EPSILON)) {
@@ -1332,9 +1316,8 @@ PHY_IPhysicsController *CcdPhysicsEnvironment::RayTest(PHY_IRayCastFilterCallbac
 		else {
 			rayCallback.m_hitNormalWorld.setValue(1.0f, 0.0f, 0.0f);
 		}
-		result.m_hitNormal[0] = rayCallback.m_hitNormalWorld.getX();
-		result.m_hitNormal[1] = rayCallback.m_hitNormalWorld.getY();
-		result.m_hitNormal[2] = rayCallback.m_hitNormalWorld.getZ();
+
+		result.m_hitNormal = ToMt(rayCallback.m_hitNormalWorld);
 		filterCallback.reportHit(&result);
 	}
 
@@ -3004,6 +2987,7 @@ void CcdPhysicsEnvironment::ConvertObject(BL_SceneConverter& converter, KX_GameO
 		// create the compound shape manually as we already have the child shape
 		btCompoundShape *compoundShape = new btCompoundShape();
 		compoundShape->addChildShape(shapeInfo->m_childTrans, bm);
+		compoundShape->setUserPointer(compoundShapeInfo);
 		// now replace the shape
 		bm = compoundShape;
 		shapeInfo->Release();