Consider hit normal for item drop test (Fixes #995)

apps/openmw/mwworld/physicssystem.cpp

@@ -492,7 +492,7 @@ namespace MWWorld
         return std::make_pair(true, ray.getPoint(len * test.second));
     }
 
-    std::pair<bool, Ogre::Vector3> PhysicsSystem::castRay(float mouseX, float mouseY)
+    std::pair<bool, Ogre::Vector3> PhysicsSystem::castRay(float mouseX, float mouseY, Ogre::Vector3* normal)
     {
         Ogre::Ray ray = mRender.getCamera()->getCameraToViewportRay(
             mouseX,
@@ -504,7 +504,7 @@ namespace MWWorld
         _from = btVector3(from.x, from.y, from.z);
         _to = btVector3(to.x, to.y, to.z);
 
-        std::pair<std::string, float> result = mEngine->rayTest(_from, _to);
+        std::pair<std::string, float> result = mEngine->rayTest(_from, _to, true, false, normal);
 
         if (result.first == "")
             return std::make_pair(false, Ogre::Vector3());

apps/openmw/mwworld/physicssystem.hpp

@@ -70,8 +70,9 @@ namespace MWWorld
             std::pair<bool, Ogre::Vector3>
             castRay(const Ogre::Vector3 &orig, const Ogre::Vector3 &dir, float len);
 
-            std::pair<bool, Ogre::Vector3> castRay(float mouseX, float mouseY);
+            std::pair<bool, Ogre::Vector3> castRay(float mouseX, float mouseY, Ogre::Vector3* normal = NULL);
-            ///< cast ray from the mouse, return true if it hit something and the first result (in OGRE coordinates)
+            ///< cast ray from the mouse, return true if it hit something and the first result
+            /// @param normal if non-NULL, the hit normal will be written there (if there is a hit)
 
             OEngine::Physic::PhysicEngine* getEngine();
 

apps/openmw/mwworld/worldimp.cpp

@@ -1620,13 +1620,16 @@ namespace MWWorld
 
     bool World::canPlaceObject(float cursorX, float cursorY)
     {
-        std::pair<bool, Ogre::Vector3> result = mPhysics->castRay(cursorX, cursorY);
+        Ogre::Vector3 normal(0,0,0);
-
+        std::pair<bool, Ogre::Vector3> result = mPhysics->castRay(cursorX, cursorY, &normal);
-        /// \todo also check if the wanted position is on a flat surface, and not e.g. against a vertical wall!
 
-        if (!result.first)
+        if (result.first)
+        {
+            // check if the wanted position is on a flat surface, and not e.g. against a vertical wall
+            return (normal.angleBetween(Ogre::Vector3(0.f,0.f,1.f)).valueDegrees() < 30);
+        }
+        else
             return false;
-        return true;
     }
 
 

libs/openengine/bullet/physic.cpp

@@ -677,7 +677,7 @@ namespace Physic
     {
     }
 
-    std::pair<std::string,float> PhysicEngine::rayTest(btVector3& from,btVector3& to,bool raycastingObjectOnly,bool ignoreHeightMap)
+    std::pair<std::string,float> PhysicEngine::rayTest(btVector3& from,btVector3& to,bool raycastingObjectOnly,bool ignoreHeightMap, Ogre::Vector3* normal)
     {
         std::string name = "";
         float d = -1;
@@ -694,7 +694,11 @@ namespace Physic
         if (resultCallback1.hasHit())
         {
             name = static_cast<const RigidBody&>(*resultCallback1.m_collisionObject).mName;
-            d = resultCallback1.m_closestHitFraction;;
+            d = resultCallback1.m_closestHitFraction;
+            if (normal)
+                *normal = Ogre::Vector3(resultCallback1.m_hitNormalWorld.x(),
+                                        resultCallback1.m_hitNormalWorld.y(),
+                                        resultCallback1.m_hitNormalWorld.z());
         }
 
         return std::pair<std::string,float>(name,d);

libs/openengine/bullet/physic.hpp

@@ -308,8 +308,10 @@ namespace Physic
 
         /**
          * Return the closest object hit by a ray. If there are no objects, it will return ("",-1).
+         * If \a normal is non-NULL, the hit normal will be written there (if there is a hit)
          */
-        std::pair<std::string,float> rayTest(btVector3& from,btVector3& to,bool raycastingObjectOnly = true,bool ignoreHeightMap = false);
+        std::pair<std::string,float> rayTest(btVector3& from,btVector3& to,bool raycastingObjectOnly = true,
+                                             bool ignoreHeightMap = false, Ogre::Vector3* normal = NULL);
 
         /**
          * Return all objects hit by a ray.