Shaders and Mouse Clicking

rayHit doesn't return the object but the intersection point,
to know if it hit an object, the object is passed in argument :

point = rayHit(start, end, object)
if point then
    -- there is a hit with object
end

Mikey shared a additional script function (written in c++) :
http://forum.maratis3d.com/viewtopic.php?id=434

Here is the function code :

int pickObject(void)
{
    MEngine * engine = MEngine::getInstance();
    MScriptContext * script = engine->getScriptContext();
    
    if (script->getArgsNumber() == 3)
    {
        MOCamera * camera = (MOCamera *)script->getPointer(0);
        float x = script->getFloat(1);
        float y = script->getFloat(2);

        MPhysicsContext * physics = engine->getPhysicsContext();
        
        unsigned int width, height;
        engine->getSystemContext()->getScreenSize(&width, &height);

        MVector3 rayO = camera->getTransformedPosition();
        MVector3 rayD = camera->getUnProjectedPoint(MVector3(x * float(width), (1 - y) * float(height), 1));
        rayD = rayO + ((rayD - rayO).getNormalized() * (camera->getClippingFar() - camera->getClippingNear()));

        unsigned int objId;
        if (physics->isRayHit(rayO, rayD, &objId))
        {
            MLevel * level = engine->getLevel();
            MScene * scene = level->getCurrentScene();
            unsigned int entCount = scene->getEntitiesNumber();
            for (unsigned int i = 0; i < entCount; ++i)
            {
                MOEntity * entity = scene->getEntityByIndex(i);
                MPhysicsProperties * phyProps = entity->getPhysicsProperties();
                if (phyProps)
                {
                    if (phyProps->getCollisionObjectId() == objId)
                    {
                        script->pushPointer(entity);
                        return 1;
                    }
                }
            }
        }
    }
    
    return 0;
}

Used like that in lua :

obj = pickObject(Camera, x, y)
if obj then
...
end

This is the way to add the function through a game plugin (to do in StartPlugin) :

MEngine* engine = MEngine::getInstance();
MScriptContext* script = engine->getScriptContext();
if(script)
    script->addFunction("pickObject", pickObject);

yes, we'll add it by default for next version.

If you want doing something with lua only, if your game is 2d you could use a ghost box and detect it's collision with objects.

For 3d it's a bit more complex, it's possible to use rayHit :
- link an object to the camera, it will act as a cursor (it will stick to the cam)
- move the cursor using the mouse position multiplied by a ratio
- you can find the ray using the cursor position and the camera position :
   beginRay = cameraPosition
   endRay = cameraPosition + (cursorPosition - cameraPosition)*factor

trying to test in Jules example project. i've set camera to follow Jules closely. the problem is i cannot detect readable camera rotation.
what axises does getRotation() function returns?
my small code:
           camRot = getRotation(camera)
           camRotX = camRot[1]
           camRotY = camRot[2]
           camRotZ = camRot[3]
           print("camera rotation:", camRotX, camRotY, camRotZ)
it returns this:
camera rotation:    63.430767059326    -8.5377365621753e-07    19.999326705933
camera rotation:    63.430732727051    -8.5377359937411e-06    104.99935150146
camera rotation:    63.430698394775    1.7075473124351e-06    -150.00065612793
camera rotation:    63.430725097656    5.122642050992e-06    -35.000694274902

so i think results are:
camRotX is rotation of camera upward from the direct down (0) to up (180)
camRotY is camera tilt
camRotZ is camera rotation left/right

now to trigonometry...