remove display lists and qt3d-ize overpainting/hellogl example

On the way to making opengl examples portable, remove display lists
and go to triangles only. Use QMatrix4x4. While on the job use Qt/3D
stylee to make the QtLogo as an example of 3D programming more Qt-like.

Reviewed-by: Rhys Weatherley

2 files changed, 470 insertions, 0 deletions

diff --git a/examples/opengl/shared/qtlogo.cpp b/examples/opengl/shared/qtlogo.cpp
new file mode 100644
index 0000000..3294da1
--- /dev/null
+++ b/examples/opengl/shared/qtlogo.cpp
@@ -0,0 +1,403 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#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());
+    else if (sizeof(qreal) == sizeof(GLdouble))
+        glMultMatrixd((GLdouble*)mat.constData());
+    else
+    {
+        GLfloat fmat[16];
+        qreal const *r = mat.constData();
+        for (int i = 0; i < 16; ++i)
+            fmat[i] = r[i];
+    }
+}
+
+//! [2]
+void Patch::draw() const
+{
+    glPushMatrix();
+    qMultMatrix(mat);
+    glMaterialfv(GL_FRONT, 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)
+{
+    QVector<QVector3D> extr = verts;
+    for (int v = 0; v < extr.count(); ++v)
+        extr[v].setZ(extr[v].z() - depth);
+    return extr;
+}
+
+class Rectoid
+{
+public:
+    void translate(const QVector3D &t)
+    {
+        for (int i = 0; i < parts.count(); ++i)
+            parts[i]->translate(t);
+    }
+    void rotate(qreal deg, QVector3D axis)
+    {
+        for (int i = 0; i < parts.count(); ++i)
+            parts[i]->rotate(deg, axis);
+    }
+
+    // No special Rectoid destructor - the parts are fetched out of this member
+    // variable, and destroyed by the new owner
+    QList<Patch*> parts;
+};
+
+class RectPrism : public Rectoid
+{
+public:
+    RectPrism(Geometry *g, qreal width, qreal height, qreal depth);
+};
+
+RectPrism::RectPrism(Geometry *g, qreal width, qreal height, qreal depth)
+{
+    enum { bl, br, tr, tl };
+    Patch *fb = new Patch(g);
+    fb->setSmoothing(Patch::Faceted);
+
+    // front face
+    QVector<QVector3D> r(4);
+    r[br].setX(width);
+    r[tr].setX(width);
+    r[tr].setY(height);
+    r[tl].setY(height);
+    QVector3D adjToCenter(-width / 2.0, -height / 2.0, depth / 2.0);
+    for (int i = 0; i < 4; ++i)
+        r[i] += adjToCenter;
+    fb->addQuad(r[bl], r[br], r[tr], r[tl]);
+
+    // back face
+    QVector<QVector3D> s = extrude(r, depth);
+    fb->addQuad(s[tl], s[tr], s[br], s[bl]);
+
+    // side faces
+    Patch *sides = new Patch(g);
+    sides->setSmoothing(Patch::Faceted);
+    sides->addQuad(s[bl], s[br], r[br], r[bl]);
+    sides->addQuad(s[br], s[tr], r[tr], r[br]);
+    sides->addQuad(s[tr], s[tl], r[tl], r[tr]);
+    sides->addQuad(s[tl], s[bl], r[bl], r[tl]);
+
+    parts << fb << sides;
+}
+
+class RectTorus : public Rectoid
+{
+public:
+    RectTorus(Geometry *g, qreal iRad, qreal oRad, qreal depth, int numSectors);
+};
+
+RectTorus::RectTorus(Geometry *g, qreal iRad, qreal oRad, qreal depth, int k)
+{
+    QVector<QVector3D> inside;
+    QVector<QVector3D> outside;
+    for (int i = 0; i < k; ++i) {
+        qreal angle = (i * 2 * M_PI) / k;
+        inside << QVector3D(iRad * qSin(angle), iRad * qCos(angle), depth / 2.0);
+        outside << QVector3D(oRad * qSin(angle), oRad * qCos(angle), depth / 2.0);
+    }
+    inside << QVector3D(0.0, iRad, 0.0);
+    outside << QVector3D(0.0, oRad, 0.0);
+    QVector<QVector3D> in_back = extrude(inside, depth);
+    QVector<QVector3D> out_back = extrude(outside, depth);
+
+    // Create front, back and sides as seperate patches so that smooth normals
+    // are generated for the curving sides, but a faceted edge is created between
+    // sides and front/back
+    Patch *front = new Patch(g);
+    for (int i = 0; i < k; ++i)
+        front->addQuad(outside[i], inside[i],
+                       inside[(i + 1) % k], outside[(i + 1) % k]);
+    Patch *back = new Patch(g);
+    for (int i = 0; i < k; ++i)
+        back->addQuad(in_back[i], out_back[i],
+                      out_back[(i + 1) % k], in_back[(i + 1) % k]);
+    Patch *is = new Patch(g);
+    for (int i = 0; i < k; ++i)
+        is->addQuad(in_back[i], in_back[(i + 1) % k],
+                    inside[(i + 1) % k], inside[i]);
+    Patch *os = new Patch(g);
+    for (int i = 0; i < k; ++i)
+        os->addQuad(out_back[(i + 1) % k], out_back[i],
+                    outside[i], outside[(i + 1) % k]);
+    parts << front << back << is << os;
+}
+
+QtLogo::QtLogo(QObject *parent, int divisions, qreal scale)
+    : QObject(parent)
+    , geom(new Geometry())
+{
+    buildGeometry(divisions, scale);
+}
+
+QtLogo::~QtLogo()
+{
+    qDeleteAll(parts);
+    delete geom;
+}
+
+void QtLogo::setColor(QColor c)
+{
+    for (int i = 0; i < parts.count(); ++i)
+        qSetColor(parts[i]->faceColor, c);
+}
+
+//! [3]
+void QtLogo::buildGeometry(int divisions, qreal scale)
+{
+    qreal cw = cross_width * scale;
+    qreal bt = bar_thickness * scale;
+    qreal ld = logo_depth * scale;
+    qreal th = tee_height *scale;
+
+    RectPrism cross(geom, cw, bt, ld);
+    RectPrism stem(geom, bt, th, ld);
+
+    QVector3D z(0.0, 0.0, 1.0);
+    cross.rotate(45.0, z);
+    stem.rotate(45.0, z);
+
+    qreal stem_downshift = (th + bt) / 2.0;
+    stem.translate(QVector3D(0.0, -stem_downshift, 0.0));
+
+    RectTorus body(geom, 0.20, 0.30, 0.1, divisions);
+
+    parts << stem.parts << cross.parts << body.parts;
+
+    geom->finalize();
+}
+//! [3]
+
+//! [4]
+void QtLogo::draw() const
+{
+    geom->loadArrays();
+
+    glEnableClientState(GL_VERTEX_ARRAY);
+    glEnableClientState(GL_NORMAL_ARRAY);
+
+    for (int i = 0; i < parts.count(); ++i)
+        parts[i]->draw();
+
+    glDisableClientState(GL_VERTEX_ARRAY);
+    glDisableClientState(GL_NORMAL_ARRAY);
+}
+//! [4]
diff --git a/examples/opengl/shared/qtlogo.h b/examples/opengl/shared/qtlogo.h
new file mode 100644
index 0000000..26508e1
--- /dev/null
+++ b/examples/opengl/shared/qtlogo.h
@@ -0,0 +1,67 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the examples of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights.  These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QTLOGO_H
+#define QTLOGO_H
+
+#include <QObject>
+#include <QtOpenGL>
+
+class Patch;
+class Geometry;
+
+//! [0]
+class QtLogo : public QObject
+{
+public:
+    QtLogo(QObject *parent, int d = 64, qreal s = 1.0);
+    ~QtLogo();
+    void setColor(QColor c);
+    void draw() const;
+private:
+    void buildGeometry(int d, qreal s);
+
+    QList<Patch *> parts;
+    Geometry *geom;
+};
+//! [0]
+
+#endif // QTLOGO_H