BGE: ray casting works on soft body, the hit polygon is also returned. The modifications to Bullet have been reported to Bullet forum. Note: welding is completely disabled on soft body as it breaks the relationship between the soft body collision shape and the graphics mesh without bringing any additional stability (the reverse actually).

2 files changed, 12 insertions, 2 deletions

diff --git a/source/gameengine/Converter/BL_BlenderDataConversion.cpp b/source/gameengine/Converter/BL_BlenderDataConversion.cpp
index d837b2c4466..31616fdec15 100644
--- a/source/gameengine/Converter/BL_BlenderDataConversion.cpp
+++ b/source/gameengine/Converter/BL_BlenderDataConversion.cpp
@@ -1458,7 +1458,9 @@ void BL_CreatePhysicsObjectNew(KX_GameObject* gameobj,
 			objprop.m_soft_kAHR= blenderobject->bsoft->kAHR;			/* Anchors hardness [0,1] */
 			objprop.m_soft_collisionflags= blenderobject->bsoft->collisionflags;	/* Vertex/Face or Signed Distance Field(SDF) or Clusters, Soft versus Soft or Rigid */
 			objprop.m_soft_numclusteriterations= blenderobject->bsoft->numclusteriterations;	/* number of iterations to refine collision clusters*/
-			objprop.m_soft_welding = blenderobject->bsoft->welding;		/* welding */
+			//objprop.m_soft_welding = blenderobject->bsoft->welding;		/* welding */
+			/* disable welding: it doesn't bring any additional stability and it breaks the relation between soft body collision shape and graphic mesh */
+			objprop.m_soft_welding = 0.f;		
 			objprop.m_margin = blenderobject->bsoft->margin;
 			objprop.m_contactProcessingThreshold = 0.f;
 		} else
diff --git a/source/gameengine/Physics/Bullet/CcdPhysicsEnvironment.cpp b/source/gameengine/Physics/Bullet/CcdPhysicsEnvironment.cpp
index 5cd20a3ec12..3d1fa6fc180 100644
--- a/source/gameengine/Physics/Bullet/CcdPhysicsEnvironment.cpp
+++ b/source/gameengine/Physics/Bullet/CcdPhysicsEnvironment.cpp
@@ -1070,6 +1070,8 @@ PHY_IPhysicsController* CcdPhysicsEnvironment::rayTest(PHY_IRayCastFilterCallbac
 					rayCallback.m_hitTriangleIndex < shapeInfo->m_polygonIndexArray.size())
 				{
 					result.m_meshObject = shapeInfo->GetMesh();
+					// note for softbody: this assumes that the softbody shape uses the same triangle numbering 
+					// than the triangle mesh shape that was used to build it
 					result.m_polygon = shapeInfo->m_polygonIndexArray.at(rayCallback.m_hitTriangleIndex);
 
 					// Bullet returns the normal from "outside".
@@ -1078,7 +1080,13 @@ PHY_IPhysicsController* CcdPhysicsEnvironment::rayTest(PHY_IRayCastFilterCallbac
 					{
 						// mesh shapes are shared and stored in the shapeInfo
 						btTriangleMeshShape* triangleShape = shapeInfo->GetMeshShape();
-						if (triangleShape)
+
+						if (shape->isSoftBody()) 
+						{
+							// we can get the real normal directly from the body
+							btSoftBody* softBody = static_cast<btSoftBody*>(rayCallback.m_collisionObject);
+							rayCallback.m_hitNormalWorld = softBody->m_faces[rayCallback.m_hitTriangleIndex].m_normal;
+						} else if (triangleShape)
 						{
 							// this code is copied from Bullet 
 							btVector3 triangle[3];