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# cube.cpp Example File
opengl/pbuffers/cube.cpp

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     #include "cube.h"
     #include "glwidget.h"

     #include <QtGui/QImage>
     #include <QtCore/QPropertyAnimation>

     static const qreal FACE_SIZE = 0.4;

     static const qreal speeds[] = { 1.8f, 2.4f, 3.6f };
     static const qreal amplitudes[] = { 2.0f, 2.5f, 3.0f };

     static inline void qSetColor(float colorVec[], QColor c)
     {
         colorVec[0] = c.redF();
         colorVec[1] = c.greenF();
         colorVec[2] = c.blueF();
         colorVec[3] = c.alphaF();
     }

     int Geometry::append(const QVector3D &a, const QVector3D &n, const QVector2D &t)
     {
         int v = vertices.count();
         vertices.append(a);
         normals.append(n);
         texCoords.append(t);
         faces.append(v);
         colors.append(QVector4D(0.6f, 0.6f, 0.6f, 1.0f));
         return v;
     }

     void Geometry::addQuad(const QVector3D &a, const QVector3D &b,
                                const QVector3D &c, const QVector3D &d,
                                const QVector<QVector2D> &tex)
     {
         QVector3D norm = QVector3D::normal(a, b, c);
         // append first triangle
         int aref = append(a, norm, tex[0]);
         append(b, norm, tex[1]);
         int cref = append(c, norm, tex[2]);
         // append second triangle
         faces.append(aref);
         faces.append(cref);
         append(d, norm, tex[3]);
     }

     void Geometry::loadArrays() const
     {
         glEnableClientState(GL_VERTEX_ARRAY);
         glEnableClientState(GL_NORMAL_ARRAY);
         glEnableClientState(GL_TEXTURE_COORD_ARRAY);
         glEnableClientState(GL_COLOR_ARRAY);
         glVertexPointer(3, GL_FLOAT, 0, vertices.constData());
         glNormalPointer(GL_FLOAT, 0, normals.constData());
         glTexCoordPointer(2, GL_FLOAT, 0, texCoords.constData());
         glColorPointer(4, GL_FLOAT, 0, colors.constData());
     }

     void Geometry::setColors(int start, GLfloat colorArray[4][4])
     {
         int off = faces[start];
         for (int i = 0; i < 4; ++i)
             colors[i + off] = QVector4D(colorArray[i][0],
                                           colorArray[i][1],
                                           colorArray[i][2],
                                           colorArray[i][3]);
     }

     Tile::Tile(const QVector3D &loc)
         : location(loc)
         , start(0)
         , count(0)
         , useFlatColor(false)
         , geom(0)
     {
         qSetColor(faceColor, QColor(Qt::darkGray));
     }

     void Tile::setColors(GLfloat colorArray[4][4])
     {
         useFlatColor = true;
         geom->setColors(start, colorArray);
     }

     static inline void qMultMatrix(const QMatrix4x4 &mat)
     {
         if (sizeof(qreal) == sizeof(GLfloat))
             glMultMatrixf((GLfloat*)mat.constData());
     #ifndef QT_OPENGL_ES
         else if (sizeof(qreal) == sizeof(GLdouble))
             glMultMatrixd((GLdouble*)mat.constData());
     #endif
         else
         {
             GLfloat fmat[16];
             qreal const *r = mat.constData();
             for (int i = 0; i < 16; ++i)
                 fmat[i] = r[i];
             glMultMatrixf(fmat);
         }
     }

     void Tile::draw() const
     {
         QMatrix4x4 mat;
         mat.translate(location);
         mat.rotate(orientation);
         glMatrixMode(GL_MODELVIEW);
         glPushMatrix();
         qMultMatrix(mat);
         glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, faceColor);
         glDrawElements(GL_TRIANGLES, count, GL_UNSIGNED_SHORT, geom->indices() + start);
         glPopMatrix();
     }

     TileBuilder::TileBuilder(Geometry *g, qreal depth, qreal size)
         : verts(4)
         , tex(4)
         , start(g->count())
         , count(0)
         , geom(g)
     {
         // front face - make a square with bottom-left at origin
         verts[br].setX(size);
         verts[tr].setX(size);
         verts[tr].setY(size);
         verts[tl].setY(size);

         // these vert numbers are good for the tex-coords
         for (int i = 0; i < 4; ++i)
             tex[i] = verts[i].toVector2D();

         // now move verts half cube width across so cube is centered on origin
         for (int i = 0; i < 4; ++i)
             verts[i] -= QVector3D(size / 2.0f, size / 2.0f, -depth);

         // add the front face
         g->addQuad(verts[bl], verts[br], verts[tr], verts[tl], tex);

         count = g->count() - start;
     }

     void TileBuilder::initialize(Tile *tile) const
     {
         tile->start = start;
         tile->count = count;
         tile->geom = geom;
         qSetColor(tile->faceColor, color);
     }

     Tile *TileBuilder::newTile(const QVector3D &loc) const
     {
         Tile *tile = new Tile(loc);
         initialize(tile);
         return tile;
     }

     Cube::Cube(const QVector3D &loc)
         : Tile(loc)
         , rot(0.0f)
         , r(0), a(0)
     {
     }

     Cube::~Cube()
     {
     }

     void Cube::setAltitude(qreal a)
     {
         if (location.y() != a)
         {
             location.setY(a);
             emit changed();
         }
     }

     void Cube::setRange(qreal r)
     {
         if (location.x() != r)
         {
             location.setX(r);
             emit changed();
         }
     }

     void Cube::setRotation(qreal r)
     {
         if (r != rot)
         {
             orientation = QQuaternion::fromAxisAndAngle(QVector3D(1.0f, 1.0f, 1.0f), r);
             emit changed();
         }
     }

     void Cube::removeBounce()
     {
         delete a;
         a = 0;
         delete r;
         r = 0;
     }

     void Cube::startAnimation()
     {
         if (r)
         {
             r->start();
             r->setCurrentTime(startx);
         }
         if (a)
             a->start();
         if (rtn)
             rtn->start();
     }

     void Cube::setAnimationPaused(bool paused)
     {
         if (paused)
         {
             if (r)
                 r->pause();
             if (a)
                 a->pause();
             if (rtn)
                 rtn->pause();
         }
         else
         {
             if (r)
                 r->resume();
             if (a)
                 a->resume();
             if (rtn)
                 rtn->resume();
         }
     }

     CubeBuilder::CubeBuilder(Geometry *g, qreal depth, qreal size)
         : TileBuilder(g, depth)
         , ix(0)
     {
         for (int i = 0; i < 4; ++i)
             verts[i].setZ(size / 2.0f);
         // back face - "extrude" verts down
         QVector<QVector3D> back(verts);
         for (int i = 0; i < 4; ++i)
             back[i].setZ(-size / 2.0f);

         // add the back face
         g->addQuad(back[br], back[bl], back[tl], back[tr], tex);

         // add the sides
         g->addQuad(back[bl], back[br], verts[br], verts[bl], tex);
         g->addQuad(back[br], back[tr], verts[tr], verts[br], tex);
         g->addQuad(back[tr], back[tl], verts[tl], verts[tr], tex);
         g->addQuad(back[tl], back[bl], verts[bl], verts[tl], tex);

         count = g->count() - start;
     }

     Cube *CubeBuilder::newCube(const QVector3D &loc) const
     {
         Cube *c = new Cube(loc);
         initialize(c);
         qreal d = 4000.0f;
         qreal d3 = d / 3.0f;
         // Animate movement from left to right
         c->r = new QPropertyAnimation(c, "range");
         c->r->setStartValue(-1.3f);
         c->r->setEndValue(1.3f);
         c->startx = ix * d3 * 3.0f;
         c->r->setDuration(d * 4.0f);
         c->r->setLoopCount(-1);
         c->r->setEasingCurve(QEasingCurve(QEasingCurve::CosineCurve));
         // Animate movement from bottom to top
         c->a = new QPropertyAnimation(c, "altitude");
         c->a->setEndValue(loc.y());
         c->a->setStartValue(loc.y() + amplitudes[ix]);
         c->a->setDuration(d / speeds[ix]);
         c->a->setLoopCount(-1);
         c->a->setEasingCurve(QEasingCurve(QEasingCurve::CosineCurve));
         // Animate rotation
         c->rtn = new QPropertyAnimation(c, "rotation");
         c->rtn->setStartValue(c->rot);
         c->rtn->setEndValue(359.0f);
         c->rtn->setDuration(d * 2.0f);
         c->rtn->setLoopCount(-1);
         c->rtn->setDuration(d / 2);
         ix = (ix + 1) % 3;
         return c;
     }