/*****************************************************************
 KWin - the KDE window manager
 This file is part of the KDE project.

Copyright (C) 2007 Lubos Lunak <l.lunak@kde.org>

You can Freely distribute this program under the GNU General Public
License. See the file "COPYING" for the exact licensing terms.
******************************************************************/

#include "fallapart.h"

#include <math.h>

#include <deleted.h>
#include <scene_opengl.h>

namespace KWinInternal
{

void FallApartEffect::prePaintScreen( int* mask, QRegion* region, int time )
    {
    if( !windows.isEmpty())
        *mask |= Scene::PAINT_SCREEN_WITH_TRANSFORMED_WINDOWS;
    effects->prePaintScreen(mask, region, time);
    }

void FallApartEffect::prePaintWindow( EffectWindow* w, int* mask, QRegion* paint, QRegion* clip, int time )
    {
    if( windows.contains( w ))
        {
        SceneOpenGL::Window* glwin = dynamic_cast< SceneOpenGL::Window* >( w->sceneWindow());
        if( glwin )
            {
            if( windows[ w ] < 1 )
                {
                windows[ w ] += time / 1000.;
                *mask |= Scene::PAINT_WINDOW_TRANSFORMED;
                glwin->enablePainting( Scene::Window::PAINT_DISABLED_BY_DELETE );
                // Request the window to be divided into cells
                glwin->requestVertexGrid( 40 );
                }
            else
                {
                windows.remove( w );
                static_cast< Deleted* >( w->window())->unrefWindow();
                }
            }
        }
    effects->prePaintWindow( w, mask, paint, clip, time );
    }

void FallApartEffect::paintWindow( EffectWindow* w, int mask, QRegion region, WindowPaintData& data )
    {
    if( windows.contains( w ))
        {
        SceneOpenGL::Window* glwin = dynamic_cast< SceneOpenGL::Window* >( w->sceneWindow() );
        if( glwin )
            {
            QVector< SceneOpenGL::Window::Vertex >& vertices = glwin->vertices();
            assert( vertices.count() % 4 == 0 );
            for( int i = 0;
                 i < vertices.count();
                 i += 4 )
                {
                // make fragments move in various directions, based on where
                // they are (left pieces generally move to the left, etc.)
                QPointF p1( vertices[ i ].pos[ 0 ], vertices[ i ].pos[ 1 ] );
                double xdiff = 0;
                if( p1.x() < w->width() / 2 )
                    xdiff = -( w->width() / 2 - p1.x()) / w->width() * 100;
                if( p1.x() > w->width() / 2 )
                    xdiff = ( p1.x() - w->width() / 2 ) / w->width() * 100;
                double ydiff = 0;
                if( p1.y() < w->height() / 2 )
                    ydiff = -( w->height() / 2 - p1.y()) / w->height() * 100;
                if( p1.y() > w->height() / 2 )
                    ydiff = ( p1.y() - w->height() / 2 ) / w->height() * 100;
                double modif = windows[ w ] * windows[ w ] * 64;
                srandom( i ); // change direction randomly but consistently
                xdiff += ( rand() % 21 - 10 );
                ydiff += ( rand() % 21 - 10 );
                for( int j = 0;
                     j < 4;
                     ++j )
                    {
                    vertices[ i + j ].pos[ 0 ] += xdiff * modif;
                    vertices[ i + j ].pos[ 1 ] += ydiff * modif;
                    }
                // also make the fragments rotate around their center
                QPointF center(( vertices[ i ].pos[ 0 ] + vertices[ i + 1 ].pos[ 0 ]
                    + vertices[ i + 2 ].pos[ 0 ] + vertices[ i + 3 ].pos[ 0 ] ) / 4,
                    ( vertices[ i ].pos[ 1 ] + vertices[ i + 1 ].pos[ 1 ]
                    + vertices[ i + 2 ].pos[ 1 ] + vertices[ i + 3 ].pos[ 1 ] ) / 4 );
                double adiff = ( rand() % 720 - 360 ) / 360. * 2 * M_PI; // spin randomly
                for( int j = 0;
                     j < 4;
                     ++j )
                    {
                    double x = vertices[ i + j ].pos[ 0 ] - center.x();
                    double y = vertices[ i + j ].pos[ 1 ] - center.y();
                    double angle = atan2( y, x );
                    angle += windows[ w ] * adiff;
                    double dist = sqrt( x * x + y * y );
                    x = dist * cos( angle );
                    y = dist * sin( angle );
                    vertices[ i + j ].pos[ 0 ] = center.x() + x;
                    vertices[ i + j ].pos[ 1 ] = center.y() + y;
                    }
                }
            glwin->markVerticesDirty();
            }
        }
    effects->paintWindow( w, mask, region, data );
    }

void FallApartEffect::postPaintScreen()
    {
    if( !windows.isEmpty())
        workspace()->addRepaintFull();
    effects->postPaintScreen();
    }

void FallApartEffect::windowClosed( EffectWindow* c )
    {
    windows[ c ] = 0;
    static_cast< Deleted* >( c->window())->refWindow();
    }

void FallApartEffect::windowDeleted( EffectWindow* c )
    {
    windows.remove( c );
    }

} // namespace