Cant get ray collision/picks working

[d4nm4n]

Can anyone help with this? i have turned off things like cameras and have set a cube to "1<<2" and the pick ID to the same but the entity is always returned null.
I have even tried hardcoding a ray that intersects the cube and still no joy. What am i doing wrong?

Code: Select all

   bbEntity* ScreenPick (s32 x,s32 y,s32 id,bool includeDebugObjects)
    {
          scene::ISceneCollisionManager* collMan = irrSmgr->getSceneCollisionManager();
          //bbLine3d ray = collMan->getRayFromScreenCoordinates(irrDevice->getCursorControl()->getPosition());
          core::line3d<f32> ray;
                ray.start = bbVector3d(-100,0,-100);

                ray.end = bbVector3d(0,0,0);
            irrDriver->draw3DLine(ray.start,ray.end);
          bbVector3d intersection;
          bbTriangle hitTriangle;
         scene::ISceneNode * selectedSceneNode =  collMan->getSceneNodeAndCollisionPointFromRay(
                                        ray,
                                        intersection, // This will be the position of the collision
                                        hitTriangle, // This will be the triangle hit in the collision
                                        id, // This ensures that only nodes that we have
                                                        // set up to be pickable are considered
                                        0
                                        ,includeDebugObjects); // Check the entire scene (this is actually the implicit default)

                                        std::cout<<intersection.X;
            return (bbEntity*)selectedSceneNode;
    }


[Memorial76]

I'm quite beginner with that but why don't you try the "getSceneNodeFromScreenCoordinatesBB()" function and make sure you call it each time you move your mouse.

I have this code that works:

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if( event.EventType == EET_MOUSE_INPUT_EVENT )
   {
         switch (event.MouseInput.Event)
         {
            case EMIE_MOUSE_MOVED:
            {
               //Récupere le sceneNode sous le curseur
               scene::ISceneNode* pHoveredSceneNode = m_pSceneMgr->getSceneCollisionManager()->getSceneNodeFromScreenCoordinatesBB(
                  m_pDevice->getCursorControl()->getPosition(),
                  0,
                  true,
                  0);

               break;
            }
                       default:
            break;

         }//switch (event.MouseInput.Event)
   return false;
}


[d4nm4n]

Thanks for the reply, unfortunately I did try that one but it only works on bounding boxes which is not what i need.

[Memorial76]

You are right,

My quesion ight seem stupid but: Are you sure to call your screenPick function each time you move youre mouse?

[d4nm4n]

yes the screenpick is being called.

I have managed to pick up a node using getCollisionPoint instead but the end point of the ray returned from the screenCoords is 0,0,0.

However, when i look at the console out of the following it seems the ray is always from world 0 rather than a relative point XYZ in the distance of direction of view.

Here is the code:

Code: Select all

    bbEntity* ScreenPick (s32 x,s32 y,scene::ITriangleSelector* selector)
    {
          scene::ISceneCollisionManager* collMan = irrSmgr->getSceneCollisionManager();
          bbLine3d ray = collMan->getRayFromScreenCoordinates(bbPosition2d(x,y));
          std::cout << ray.start.X<<" "<<ray.end.X<<" ";
          std::cout << ray.start.Y<<" "<<ray.end.Y<<" ";
          std::cout << ray.start.Z<<" "<<ray.end.Z<<"\n";


         if (!selector) selector = irrGlobalSceneryMetaSelector;
          irr::core::vector3df intersection;
          irr::core::triangle3df hitTriangle;
         const scene::ISceneNode * selectedSceneNode=0;
         collMan->getCollisionPoint(  ray,
                                        selector,
                                        intersection,
                                        hitTriangle,
                                        selectedSceneNode);

            return (bbEntity*)selectedSceneNode;
    }

[blAaarg]

It appears getRayFromScreenCoordinates() returns the camera's position as the ray.start member of the line3d it returns. The ray.end should be a position on the far frustum and those are the values this code is going to print out. Is your camera at the world origin 0?

Then your intersection and hitTriangle appear to be created local to the ScreenPick function and so they "evaporate" when it returns, leaving you with only an ISceneNode cast as a bbEntity pointer to work with. I'm not sure what that little guy's supposed to do but it doesn't appear to store those objects before returning, if that's what you're going for.

[d4nm4n]

bbEntity is a custom scenenode, and eventually i will need the other values, but mostly want node mesh specific picking from a screen position but nothing seems to work as i would expect.

This seems to work kind of but it is not right. The resulting node seems to jump between them, almost as if it is clipping them wrongly.

Code: Select all

         collMan->getCollisionPoint(  ray,
                                        selector,
                                        intersection,
                                        hitTriangle,
                                        selectedSceneNode);
std::cout<<selectedSceneNode<<'\n';


This seems a bit better but still not right, it also seems to be only using bounding boxes.

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            selectedSceneNode = collMan->getSceneNodeFromRayBB(ray,1<<2,true,0);
std::cout<<selectedSceneNode<<'\n';


This one doesnt seem to work at all.

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            selectedSceneNode = collMan->getSceneNodeAndCollisionPointFromRay(
                        ray,
                        intersection,
                        hitTriangle,
                        1<<2,
                        0,
                        true);
            std::cout<<selectedSceneNode<<'\n';


[d4nm4n]

Solved it

The first ones of the above work but it has to be a precision mesh tri selector!. I was using octree!

(not quite sure what the point in the 3rd one is though it seems to do the same as the first.. except actually work )