source: trunk/examples/opengl/shared/qtlogo.cpp@ 886

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#include <QGLWidget>
#include <QMatrix4x4>
#include <QVector3D>

#include <qmath.h>

#include "qtlogo.h"

static const qreal tee_height = 0.311126;
static const qreal cross_width = 0.25;
static const qreal bar_thickness = 0.113137;
static const qreal inside_diam = 0.20;
static const qreal outside_diam = 0.30;
static const qreal logo_depth = 0.10;
static const int num_divisions = 32;

//! [0]
struct Geometry
{
    QVector<GLushort> faces;
    QVector<QVector3D> vertices;
    QVector<QVector3D> normals;
    void appendSmooth(const QVector3D &a, const QVector3D &n, int from);
    void appendFaceted(const QVector3D &a, const QVector3D &n);
    void finalize();
    void loadArrays() const;
};
//! [0]

//! [1]
class Patch
{
public:
    enum Smoothing { Faceted, Smooth };
    Patch(Geometry *);
    void setSmoothing(Smoothing s) { sm = s; }
    void translate(const QVector3D &t);
    void rotate(qreal deg, QVector3D axis);
    void draw() const;
    void addTri(const QVector3D &a, const QVector3D &b, const QVector3D &c, const QVector3D &n);
    void addQuad(const QVector3D &a, const QVector3D &b,  const QVector3D &c, const QVector3D &d);

    GLushort start;
    GLushort count;
    GLushort initv;

    GLfloat faceColor[4];
    QMatrix4x4 mat;
    Smoothing sm;
    Geometry *geom;
};
//! [1]

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

void Geometry::loadArrays() const
{
    glVertexPointer(3, GL_FLOAT, 0, vertices.constData());
    glNormalPointer(GL_FLOAT, 0, normals.constData());
}

void Geometry::finalize()
{
    // TODO: add vertex buffer uploading here

    // Finish smoothing normals by ensuring accumulated normals are returned
    // to length 1.0.
    for (int i = 0; i < normals.count(); ++i)
        normals[i].normalize();
}

void Geometry::appendSmooth(const QVector3D &a, const QVector3D &n, int from)
{
    // Smooth normals are acheived by averaging the normals for faces meeting
    // at a point.  First find the point in geometry already generated
    // (working backwards, since most often the points shared are between faces
    // recently added).
    int v = vertices.count() - 1;
    for ( ; v >= from; --v)
        if (qFuzzyCompare(vertices[v], a))
            break;
    if (v < from)
    {
        // The vert was not found so add it as a new one, and initialize
        // its corresponding normal
        v = vertices.count();
        vertices.append(a);
        normals.append(n);
    }
    else
    {
        // Vert found, accumulate normals into corresponding normal slot.
        // Must call finalize once finished accumulating normals
        normals[v] += n;
    }
    // In both cases (found or not) reference the vert via its index
    faces.append(v);
}

void Geometry::appendFaceted(const QVector3D &a, const QVector3D &n)
{
    // Faceted normals are achieved by duplicating the vert for every
    // normal, so that faces meeting at a vert get a sharp edge.
    int v = vertices.count();
    vertices.append(a);
    normals.append(n);
    faces.append(v);
}

Patch::Patch(Geometry *g)
   : start(g->faces.count())
   , count(0)
   , initv(g->vertices.count())
   , sm(Patch::Smooth)
   , geom(g)
{
    qSetColor(faceColor, QColor(Qt::darkGray));
}

void Patch::rotate(qreal deg, QVector3D axis)
{
    mat.rotate(deg, axis);
}

void Patch::translate(const QVector3D &t)
{
    mat.translate(t);
}

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);
    }
}

//! [2]
void Patch::draw() const
{
    glPushMatrix();
    qMultMatrix(mat);
    glMaterialfv(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE, faceColor);

    const GLushort *indices = geom->faces.constData();
    glDrawElements(GL_TRIANGLES, count, GL_UNSIGNED_SHORT, indices + start);
    glPopMatrix();
}
//! [2]

void Patch::addTri(const QVector3D &a, const QVector3D &b, const QVector3D &c, const QVector3D &n)
{
    QVector3D norm = n.isNull() ? QVector3D::normal(a, b, c) : n;
    if (sm == Smooth)
    {
        geom->appendSmooth(a, norm, initv);
        geom->appendSmooth(b, norm, initv);
        geom->appendSmooth(c, norm, initv);
    }
    else
    {
        geom->appendFaceted(a, norm);
        geom->appendFaceted(b, norm);
        geom->appendFaceted(c, norm);
    }
    count += 3;
}

void Patch::addQuad(const QVector3D &a, const QVector3D &b,  const QVector3D &c, const QVector3D &d)
{
    QVector3D norm = QVector3D::normal(a, b, c);
    if (sm == Smooth)
    {
        addTri(a, b, c, norm);
        addTri(a, c, d, norm);
    }
    else
    {
        // If faceted share the two common verts
        addTri(a, b, c, norm);
        int k = geom->vertices.count();
        geom->appendSmooth(a, norm, k);
        geom->appendSmooth(c, norm, k);
        geom->appendFaceted(d, norm);
        count += 3;
    }
}

static inline QVector<QVector3D> extrude(const QVector<QVector3D> &verts, qreal depth)
{