Fixed segmented raycast missing collisions by overlapping ray segments.

Source/Urho3D/AngelScript/PhysicsAPI.cpp

@@ -243,10 +243,10 @@ static PhysicsRaycastResult PhysicsWorldRaycastSingle(const Ray& ray, float maxD
     return result;
 }
 
-static PhysicsRaycastResult PhysicsWorldRaycastSingleSegmented(const Ray& ray, float maxDistance, float segmentDistance, unsigned collisionMask, PhysicsWorld* ptr)
+static PhysicsRaycastResult PhysicsWorldRaycastSingleSegmented(const Ray& ray, float maxDistance, float segmentDistance, unsigned collisionMask, float overlapDistance, PhysicsWorld* ptr)
 {
     PhysicsRaycastResult result;
-    ptr->RaycastSingleSegmented(result, ray, maxDistance, segmentDistance, collisionMask);
+    ptr->RaycastSingleSegmented(result, ray, maxDistance, segmentDistance, collisionMask, overlapDistance);
     return result;
 }
 
@@ -312,7 +312,7 @@ static void RegisterPhysicsWorld(asIScriptEngine* engine)
     engine->RegisterObjectMethod("PhysicsWorld", "void UpdateCollisions()", asMETHOD(PhysicsWorld, UpdateCollisions), asCALL_THISCALL);
     engine->RegisterObjectMethod("PhysicsWorld", "Array<PhysicsRaycastResult>@ Raycast(const Ray&in, float, uint collisionMask = 0xffff)", asFUNCTION(PhysicsWorldRaycast), asCALL_CDECL_OBJLAST);
     engine->RegisterObjectMethod("PhysicsWorld", "PhysicsRaycastResult RaycastSingle(const Ray&in, float, uint collisionMask = 0xffff)", asFUNCTION(PhysicsWorldRaycastSingle), asCALL_CDECL_OBJLAST);
-    engine->RegisterObjectMethod("PhysicsWorld", "PhysicsRaycastResult RaycastSingleSegmented(const Ray&in, float, float, uint collisionMask = 0xffff)", asFUNCTION(PhysicsWorldRaycastSingleSegmented), asCALL_CDECL_OBJLAST);
+    engine->RegisterObjectMethod("PhysicsWorld", "PhysicsRaycastResult RaycastSingleSegmented(const Ray&in, float, float, uint collisionMask = 0xffff, float overlapDistance = 0.1f)", asFUNCTION(PhysicsWorldRaycastSingleSegmented), asCALL_CDECL_OBJLAST);
     engine->RegisterObjectMethod("PhysicsWorld", "PhysicsRaycastResult SphereCast(const Ray&in, float, float, uint collisionMask = 0xffff)", asFUNCTION(PhysicsWorldSphereCast), asCALL_CDECL_OBJLAST);
     // There seems to be a bug in AngelScript resulting in a crash if we use an auto handle with this function.
     // Work around by manually releasing the CollisionShape handle

Source/Urho3D/Physics/PhysicsWorld.cpp

@@ -429,10 +429,12 @@ void PhysicsWorld::RaycastSingle(PhysicsRaycastResult& result, const Ray& ray, f
     }
 }
 
-void PhysicsWorld::RaycastSingleSegmented(PhysicsRaycastResult& result, const Ray& ray, float maxDistance, float segmentDistance, unsigned collisionMask)
+void PhysicsWorld::RaycastSingleSegmented(PhysicsRaycastResult& result, const Ray& ray, float maxDistance, float segmentDistance, unsigned collisionMask, float overlapDistance)
 {
     URHO3D_PROFILE(PhysicsRaycastSingleSegmented);
 
+    assert(overlapDistance < segmentDistance);
+
     if (maxDistance >= M_INFINITY)
         URHO3D_LOGWARNING("Infinite maxDistance in physics raycast is not supported");
 
@@ -440,6 +442,8 @@ void PhysicsWorld::RaycastSingleSegmented(PhysicsRaycastResult& result, const Ra
     const auto count = CeilToInt(maxDistance / segmentDistance);
 
     btVector3 start = ToBtVector3(ray.origin_);
+    // overlap a bit with the previous segment for better precision, to avoid missing hits
+    const btVector3 overlap = direction * overlapDistance;
     float remainingDistance = maxDistance;
 
     for (auto i = 0; i < count; ++i)
@@ -465,7 +469,7 @@ void PhysicsWorld::RaycastSingleSegmented(PhysicsRaycastResult& result, const Ra
         }
 
         // Use the end position as the new start position
-        start = end;
+        start = end - overlap;
         remainingDistance -= segmentDistance;
     }
 

Source/Urho3D/Physics/PhysicsWorld.h

@@ -189,7 +189,8 @@ public:
     /// Perform a physics world raycast and return the closest hit.
     void RaycastSingle(PhysicsRaycastResult& result, const Ray& ray, float maxDistance, unsigned collisionMask = M_MAX_UNSIGNED);
     /// Perform a physics world segmented raycast and return the closest hit. Useful for big scenes with many bodies.
-    void RaycastSingleSegmented(PhysicsRaycastResult& result, const Ray& ray, float maxDistance, float segmentDistance, unsigned collisionMask = M_MAX_UNSIGNED);
+    /// overlapDistance is used to make sure there are no gap between segments, and must be smaller than segmentDistance.
+    void RaycastSingleSegmented(PhysicsRaycastResult& result, const Ray& ray, float maxDistance, float segmentDistance, unsigned collisionMask = M_MAX_UNSIGNED, float overlapDistance = 0.1f);
     /// Perform a physics world swept sphere test and return the closest hit.
     void SphereCast
         (PhysicsRaycastResult& result, const Ray& ray, float radius, float maxDistance, unsigned collisionMask = M_MAX_UNSIGNED);