Fader.cpp

#include "fader.h"
#include "windows.h"	// for MessageBox
#include "OgreMaterialManager.h"
#include "OgreOverlayManager.h"
#include "OgreTechnique.h"
#include "OgreBlendMode.h"

using namespace Ogre;

Fader::Fader(const char *OverlayName, const char *MaterialName, FaderCallback *instance)
{
	try
	{
		_fadeop = FADE_NONE;
		_alpha = 0.0;
		_inst = instance;

		// Get the material by name
		Ogre::ResourcePtr resptr = Ogre::MaterialManager::getSingleton().getByName(MaterialName);
		Ogre::Material * mat = dynamic_cast<Ogre::Material*>(resptr.getPointer());

		Ogre::Technique *tech = mat->getTechnique(0);	// Get the technique
		Ogre::Pass *pass = tech->getPass(0);			// Get the pass
		_tex_unit = pass->getTextureUnitState(0);		// Get the texture_unit state
		//_tex_unit->setColourOperationEx(
		// Get the _overlay
		_overlay = Ogre::OverlayManager::getSingleton().getByName(OverlayName);
		_overlay->hide();

	} catch(Ogre::Exception e) {
		MessageBox(NULL, e.getFullDescription().c_str(), "Fader Exception", MB_OK | MB_ICONERROR | MB_TASKMODAL);
	} catch(...) {
		MessageBox(NULL, "An unknown exception has occured while setting up the fader.  Scene fading will not be supported.", "Fader Exception", MB_OK | MB_ICONERROR | MB_TASKMODAL);
	}
}

Fader::~Fader(void)
{
	_overlay->hide();
	_overlay->clear();
	delete _overlay;
}

void Fader::startFadeIn(double duration )
{
	if( duration < 0 )
		duration = -duration;
	if( duration < 0.000001 )
		duration = 1.0;

	_alpha = 1.0;
	_total_dur = duration;
	_current_dur = duration;
	_fadeop = FADE_IN;
	_overlay->show();
}

void Fader::startFadeOut(double duration )
{
	if( duration < 0 )
		duration = -duration;
	if( duration < 0.000001 )
		duration = 1.0;

	_alpha = 0.0;
	_total_dur = duration;
	_current_dur = 0.0;
	_fadeop = FADE_OUT;
	_overlay->show();
}

void Fader::fade(double timeSinceLastFrame)
{
	if( _fadeop != FADE_NONE && _tex_unit )
	{
		// Set the _alpha value of the _overlay
		_tex_unit->setAlphaOperation(LBX_MODULATE, LBS_MANUAL, LBS_TEXTURE, _alpha);	// Change the _alpha operation

		// If fading in, decrease the _alpha until it reaches 0.0
		if( _fadeop == FADE_IN )
		{
			_current_dur -= timeSinceLastFrame;
			_alpha = _current_dur / _total_dur;
			if( _alpha < 0.0 )
			{
				_overlay->hide();
				_fadeop = FADE_NONE;
				if( _inst )
					_inst->fadeInCallback();
			}
		}

		// If fading out, increase the _alpha until it reaches 1.0
		else if( _fadeop == FADE_OUT )
		{
			_current_dur += timeSinceLastFrame;
			_alpha = _current_dur / _total_dur;
			if( _alpha > 1.0 )
			{
				_fadeop = FADE_NONE;
				if( _inst )
					_inst->fadeOutCallback();
			}
		}
	}
}