JoystickCameraAnimator

MickeyKnox · Post by **MickeyKnox** » Sat Mar 14, 2009 1:38 pm

I managed to write an Animator that processes input from a Joystick to move a camera.
It actually supports some low level physics by calculating the movement speed from
some Acceleration / Attenuation values.

Here is the code:

JoystickCameraAnimator.h

Code: Select all

#ifndef __JOYSTICKCAMERAANIMATOR_H__
#define __JOYSTICKCAMERAANIMATOR_H__

#include <irrlicht.h>

class JoystickCameraAnimator : public irr::scene::ISceneNodeAnimator
{
  static const irr::u32 BrakeButton = 6;

  irr::u32 LastAnimationTime;

  irr::core::vector3df rotation;
  irr::f32 Acceleration, Velocity, Brake;
  irr::f32 MaxRoll, MaxPitch, MaxAcceleration, Attenuation, MaxBrake;

public:
  JoystickCameraAnimator(irr::f32 maxRoll, irr::f32 maxPitch, irr::f32 maxAcceleration,
			 irr::f32 attenuation, irr::f32 brake)
  :
    Velocity(0), MaxRoll(maxRoll), MaxPitch(maxPitch), MaxAcceleration(maxAcceleration),
    Attenuation(attenuation), MaxBrake(brake)
  {}

  virtual ~JoystickCameraAnimator() {}

  virtual irr::scene::ISceneNodeAnimator* createClone(irr::scene::ISceneNode*, irr::scene::ISceneManager*)
  {
    return new JoystickCameraAnimator(MaxRoll, MaxPitch, MaxAcceleration, Attenuation, MaxBrake);
  }

  virtual bool isEventReceiverEnabled() const
  {
    return true;
  }

  virtual bool OnEvent(const irr::SEvent&);
  virtual void animateNode(irr::scene::ISceneNode*, irr::u32);
};

#endif /*__JOYSTICKCAMERAANIMATOR_H__*/

JoystickCameraAnimator.cpp

Code: Select all

#include "JoystickCameraAnimator.h"

using namespace irr;

bool JoystickCameraAnimator::OnEvent(const SEvent &event)
{
  if (event.EventType == irr::EET_JOYSTICK_INPUT_EVENT)
    {
      rotation.X = (f32) event.JoystickEvent.Axis[1] / 32768 * MaxPitch * -1;
      rotation.Z = (f32) event.JoystickEvent.Axis[0] / 32768 * MaxRoll * -1;

      Acceleration = (f32) (event.JoystickEvent.Axis[2] - 32768) / 65536 * -1;
      if (Acceleration < 0.0001) Acceleration = 0;
      Acceleration *= MaxAcceleration;

      if (event.JoystickEvent.IsButtonPressed(BrakeButton))
        Brake = MaxBrake;
      else
        Brake = 0;
  
      return true;
    }
  else return false;
}

void JoystickCameraAnimator::animateNode(scene::ISceneNode *node, u32 time)
{
  if (node->getType() != scene::ESNT_CAMERA) return;
  scene::ICameraSceneNode* camera = static_cast< scene::ICameraSceneNode* >(node);

  f32 timeDiff = (f32) ( time - LastAnimationTime );
  LastAnimationTime = time;

  rotation *= timeDiff;

  core::matrix4 m, n;
  m.setRotationDegrees(camera->getRotation());
  n.setRotationDegrees(rotation);
  m *= n;

  camera->setRotation(m.getRotationDegrees());
  
  Velocity += (Acceleration - Velocity * Velocity * Attenuation - Brake) * timeDiff;
  if (Velocity < 0.01) Velocity = 0;

  core::vector3df distance(0.0f, 0.0f, Velocity);
  m.transformVect(distance);
  camera->setPosition(camera->getPosition() + distance);
  
  core::vector3df upvector(0.0f, 1.0f, 0.0f);
  m.transformVect(upvector);
  camera->setUpVector(upvector);

  core::vector3df forward(0.0f, 0.0f, 1.0f);
  m.transformVect(forward);
  camera->setTarget(camera->getPosition() + forward);

  camera->updateAbsolutePosition(); 
}

Use it like this:

Code: Select all

	scene::ICameraSceneNode* camera = smgr->addCameraSceneNode();
	scene::ISceneNodeAnimator* anm = new JoystickCameraAnimator(0.2, 0.1, 0.02, 0.0005, 0.01);

	smgr->setActiveCamera(camera);
	camera->addAnimator(anm);

	anm->drop();

What do you think?

bitplane · Post by **bitplane** » Sat Mar 14, 2009 4:48 pm

Cool, nice to see someone using the camera animators

I guess we should really provide something like this built in to the FPS camera

christianclavet · Post by **christianclavet** » Sat Mar 14, 2009 7:56 pm

Hummm...

Thanks for the code MickeyKnox!

Bitplane that look VERY interesting for me! Refering to this code, I could surely adapt my FPS camera code to an animator. Just need more free time.

EDIT: Can I still put a CollisionResponseAnimator with the FPS animator? If yes, is there a specific order?

If multiple animators can be put and removed; I could change "rigs" at runtime! (Like passing from a walking rig to a vehicule rig, to a ladder etc...)