Jump only on floor not int the air.

Hi all,

I would like to jump a NxOgre body into my app but only if this one is on floor. You can't jump if you are always in the air

Today when i press space key i add "y" force to my body:

bool GameFrameListener::keyPressed(const OIS::KeyEvent &e) {
if(e.key == OIS::KC_SPACE) {
mForceVector.y = mForceApply; // int value : 20
}
return true;
}

Into Framestarted i had:

bool GameFrameListener::frameStarted(const FrameEvent& evt) {

mTimeController->advance(evt.timeSinceLastFrame);

if(mKeyboard)
mKeyboard->capture();

// Apply for on body
mBody->addForce(mForceVector);

return (true);
}

1 - How can perform a test which be able to say me: If body in the air then no force is applied. A raycast from body to plane will be able to do that? By getting the distance of the ray?

Thanks for your support,

Thomas

Yes, raycast is exactly what you need to determine, whether your body is in the air or not.
Just use Scene::raycastClosestShape() pointing it straight down. And don't forget to correct its origin, that it doesn't hit your body, which position you are testing

that it doesn't hit your body

I believe you can cast within side a shape and that shape won't get reported, I think I did it with the Fake Camera Actor in Cake.

Makes things easier when working out ray origin positions.

I am trying for that:

bool GameFrameListener::keyPressed(const OIS::KeyEvent &e) {
if(e.key == OIS::KC_SPACE) {

NxOgre::Vec3 bodyPos = NxOgre::Vec3(mBody->getGlobalPosition());

mBodyRayHit = mScene->raycastClosestShape( NxOgre::Ray(bodyPos, NxOgre::Vec3(bodyPos.x, -10, bodyPos.z)),
NxOgre::Enums::ShapesType_Static);

if(mBodyRayHit.mDistance == 0) {
mForceVector.y = mForceApply;
LogManager::getSingletonPtr()->logMessage("IF zone");
} else {
LogManager::getSingletonPtr()->logMessage("ELSE zone");
}

}
}

I declared into my members the following variable:

NxOgre::RaycastHit mBodyRayHit;

Problem: i cannot jump the body. My "Ogre.log" file always write "ELSE zone" regarding to my log message on the first block of code i posted.
LogManager::getSingletonPtr()->logMessage("ELSE zone");

The body jump from a plane declared like this:

// Create floor plane (BloodyMess)
mScene->createSceneGeometry(new NxOgre::PlaneGeometry(0, NxOgre::Vec3(0, 1, 0)), Matrix44_Identity);

// Create floor plane (Ogre)
MovablePlane *plane = new MovablePlane("Plane");
plane->d = 0;
plane->normal = Vector3::UNIT_Y;
Ogre::MeshManager::getSingleton().createPlane("PlaneMesh",
ResourceGroupManager::DEFAULT_RESOURCE_GROUP_NAME,
*plane, 120, 120, 1, 1, true, 1, 3, 3, Vector3::UNIT_Z);
Entity *planeEnt = mSceneManager->createEntity("PlaneEntity", "PlaneMesh");
planeEnt->setMaterialName("Examples/NxFloor");

planeEnt->setCastShadows(false);

Ogre::SceneNode* mPlaneNode = mSceneManager->getRootSceneNode()->createChildSceneNode();
mPlaneNode->attachObject(planeEnt);

1 - What's going wrong?

I believe you can cast within side a shape and that shape won't get reported

2 - i'am quite interested about this feature. How does it works? Which function i have to use?

Thanks for the support you bring to me,

Thomas (from france).

Your object probably not at 0 distance from the ground. It may stay at 0.0001 for example, close enough, but not at zero. It's not a good idea to test float vars for equality to smth. Try to replace your condition for example with:
mBodyRayHit.mDistance < 0.1

To betajaen:
I have an expirience with raycasts, when my object start flying away exactly because it get reported as a query result. I had to change Shape type to NxOgre::Enums::ShapesType_Static to avoid false reports.

I think the problem is in this line

if(mBodyRayHit.mDistance == 0)
because it may never reach to zero

I suggest you to print the mDistance value and check whether what is the it when the body is on the floor. Following is my code
void PlayerCharacter::jumpPlayer()
{
// ray casting
NxOgre::RaycastHit hit;
hit = gameEngData->mScene->raycastClosestShape(NxOgre::Ray(NxOgre::Vec3(characterNode->getPosition().x,characterNode->getPosition().y,characterNode->getPosition().z),NxOgre::Vec3(0,-1,0)),NxOgre::Enums::ShapesType_Static,1,40);

if(hit.mDistance < MINIMUM_FLOUR_TOUCH_LIMIT)
this->playerBody->addForce(NxOgre::Vec3(0,fpForceJumpPower,0), NxOgre::Enums::ForceMode_Force);
}

EDIT: Oh druha almost posted the code

Your object probably not at 0 distance from the ground. It may stay at 0.0001 for example, close enough, but not at zero. It's not a good idea to test float vars for equality to smth. Try to replace your condition for example with:
mBodyRayHit.mDistance < 0.1


Unfortunately it's not working with

mBodyRayHit.mDistance < 0.1

The definition of my ray is really correct? I use Vec3(mBody.x, -10, mBody.z) for the second vector of my ray:

mBodyRayHit = mScene->raycastClosestShape( NxOgre::Ray(bodyPos, NxOgre::Vec3(bodyPos.x, -10, bodyPos.z)),
NxOgre::Enums::ShapesType_Static);

Thanks for the support,

Thomas

Unfortunately it's not working with

mBodyRayHit.mDistance < 0.1



It Works with more greater value: 1 instead of 0.1
mBodyRayHit.mDistance < 1

1 - There is a way to debug raycast? To view on screen my ray? Which plane or actor, body does he hit?

Thanks all!

Thomas

The definition of my ray is really correct? I use Vec3(mBody.x, -10, mBody.z) for the second vector of my ray:
mBodyRayHit = mScene->raycastClosestShape( NxOgre::Ray(bodyPos, NxOgre::Vec3(bodyPos.x, -10, bodyPos.z)),
NxOgre::Enums::ShapesType_Static);

The second vector in Ray constructor is a direction vector. In your case there should be NxOgre::Vec3(0,-1,0)
The one you are using now after normalisation may point in almost any direction, but not down

The definition of my ray is really correct? I use Vec3(mBody.x, -10, mBody.z) for the second vector of my ray:
mBodyRayHit = mScene->raycastClosestShape( NxOgre::Ray(bodyPos, NxOgre::Vec3(bodyPos.x, -10, bodyPos.z)),
NxOgre::Enums::ShapesType_Static);

The second vector in Ray constructor is a direction vector. In your case there should be NxOgre::Vec3(0,-1,0)
The one you are using now after normalisation may point in almost any direction, but not down

Ok i understand and i correct. Thanks.

I ask again about the debug:

1 - There's a way to view Ray on the scene to debug?

2 - There is a to make a "surface ray" which describe a volume? This volume could intersec with other bodies, actor or static shape...

Thanks for support,

Thomas

1. No not really. Rays are preformed instantaneously, so they are to quick to be drawn. You can use an Ogre::ManualObject though to draw a line though.

2. Yep. You can use sweep testing if you like, it should be accessible via Scene.


However, I am really surprised how much difficulty you have had with this. Honestly it isn't hard to do.

I'll assume your player is 2 metres high, has a default skin width of 0.025:

float minFloorHeight = (2 * 0.5) + 0.025 + 0.05) // Half the height + skin width + 0.05 safety.

if (mScene->raycastAnyShape(NxOgre::Ray(bodyPos, NxOgre::Vec3(0,-1,0)), NxOgre::Enums::ShapesType_Static, INT_MAX, minFloorHeight)
; // On Floor
else
; // In air

Thanks for the support.