view.cpp Example File

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 #include "view.h"
 #include "teapot.h"
 #include "cube.h"
 #include <QtCore/qdebug.h>
 #include <QtCore/qtimer.h>
 #include <stdio.h>
 #include "qaccelerometer.h"

 #if defined(QT_OPENGL_ES)
 #define USE_BUFFERS 1
 #endif

 class smoothedaccelerometerfilter : public QObject, public QAccelerometerFilter
 {
     qreal prevX;
     qreal prevY;
     qreal prevZ;
     bool havePrev;

 public:
     smoothedaccelerometerfilter(QObject *parent = 0)
         : QObject(parent)
         , QAccelerometerFilter()
         , prevX(0)
         , prevY(0)
         , prevZ(0)
         , havePrev(false)
     {
     }

     bool filter(QAccelerometerReading *reading)
     {
         // Smooth out the reported values.  Large changes are applied as-is,
         // and small jitters smooth to the rest position.
         if (havePrev) {
             qreal xdiff = reading->x() - prevX;
             qreal ydiff = reading->y() - prevY;
             qreal zdiff = reading->z() - prevZ;
 #define threshold 0.196133f
             if (qAbs(xdiff) < threshold && qAbs(ydiff) < threshold && qAbs(zdiff) < threshold) {
                 reading->setX(prevX + xdiff * 0.1f);
                 reading->setY(prevY + ydiff * 0.1f);
                 reading->setZ(prevZ + zdiff * 0.1f);
             }
         }
         prevX = reading->x();
         prevY = reading->y();
         prevZ = reading->z();
         havePrev = true;
         return true;
     }
 };

 View::View(QWidget *parent)
     : QGLWidget(parent),
       sensitivity(0.1f),
       painter(0),
       showFrameRate(false)
 {
 #if (QT_VERSION >= QT_VERSION_CHECK(4, 7, 2))
     setAttribute(Qt::WA_LockPortraitOrientation);
 #endif

     mainCamera = new Camera(this);

     roomCamera = new Camera(this);
     roomCamera->setAdjustForAspectRatio(false);

     sensor = new QAccelerometer(this);
     connect(sensor, SIGNAL(readingChanged()), this, SLOT(accelerometerTimeout()));
     sensor->addFilter(new smoothedaccelerometerfilter(this));
     sensor->start();

     time.start();

     vertexBuffer = 0;
     indexBuffer = 0;
 }

 View::~View()
 {
     delete painter;
 }

 void View::resizeGL(int width, int height)
 {
     glViewport(0, 0, width, height);
 }

 void View::initializeGL()
 {
 #if defined(QT_OPENGL_ES_2)
     painter = new ShaderPainter();
 #else
     painter = new FixedFunctionPainter();
 #endif

     glEnable(GL_DEPTH_TEST);

     roomMaterialBack = new Material();
     roomMaterialBack->setDiffuseColor(QColor(128, 100, 0));

     roomMaterialLeftRight = new Material();
     roomMaterialLeftRight->setDiffuseColor(Qt::cyan);

     roomMaterialTopBottom = new Material();
     roomMaterialTopBottom->setDiffuseColor(Qt::yellow);

     cubeMaterial = new Material();
     cubeMaterial->setColor(QColor(170, 202, 0));

     teapotMaterial = new Material();
     teapotMaterial->setAmbientColor(QColor(192, 150, 128));
     teapotMaterial->setSpecularColor(QColor(60, 60, 60));
     teapotMaterial->setShininess(128);

     roomModel = new LightModel(this);
     roomModel->setAmbientSceneColor(Qt::white);
     roomModel->setViewerPosition(LightModel::LocalViewer);

     normalModel = new LightModel(this);

     Light *light = new Light(this);
     light->setPosition(QVector3D(0.0f, 0.0f, 3.0f));
     painter->setLight(light);

     texture = bindTexture(QImage(QLatin1String(":/qtlogo.png")));

 #ifdef USE_BUFFERS
     // Upload the teapot data into GL buffers for quicker rendering.
     glGenBuffers(1, &vertexBuffer);
     glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
     glBufferData(GL_ARRAY_BUFFER,
                  teapotVertexCount * teapotVertexStride * sizeof(float),
                  teapotVertexData, GL_STATIC_DRAW);
     glBindBuffer(GL_ARRAY_BUFFER, 0);

     glGenBuffers(1, &indexBuffer);
     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
     glBufferData(GL_ELEMENT_ARRAY_BUFFER,
                  teapotTriangleCount * 3 * sizeof(ushort),
                  teapotTriangleData, GL_STATIC_DRAW);
     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
 #endif
 }

 void View::paintGL()
 {
     if (showFrameRate)
         qWarning("time since last frame: %d ms", time.restart());

     qreal aspectRatio = qreal(width()) / qreal(height());
     QMatrix4x4 mv, mv2;
     QMatrix4x4 proj;

     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

     mv = roomCamera->modelViewMatrix();
     proj = roomCamera->projectionMatrix(aspectRatio);
     painter->setLightModel(roomModel);
     painter->setMatrices(mv, proj);

     painter->selectMaterial(roomMaterialBack);
     painter->drawQuad(QVector3D(-3.0f, -3.0f, -15.0f),
                       QVector3D( 3.0f, -3.0f, -15.0f),
                       QVector3D( 3.0f,  3.0f, -15.0f),
                       QVector3D(-3.0f,  3.0f, -15.0f),
                       QVector3D(0.0f, 0.0f, 1.0f));

     painter->selectMaterial(roomMaterialLeftRight);
     painter->drawQuad(QVector3D(-3.0f, -3.0f, -15.0f),
                       QVector3D(-3.0f,  3.0f, -15.0f),
                       QVector3D(-3.0f,  3.0f, 0.0f),
                       QVector3D(-3.0f, -3.0f, 0.0f),
                       QVector3D(1.0f, 0.0f, 0.0f));
     painter->drawQuad(QVector3D(3.0f,  3.0f, -15.0f),
                       QVector3D(3.0f, -3.0f, -15.0f),
                       QVector3D(3.0f, -3.0f, 0.0f),
                       QVector3D(3.0f,  3.0f, 0.0f),
                       QVector3D(-1.0f, 0.0f, 0.0f));

     painter->selectMaterial(roomMaterialTopBottom);
     painter->drawQuad(QVector3D(-3.0f,  3.0f, -15.0f),
                       QVector3D( 3.0f,  3.0f, -15.0f),
                       QVector3D( 3.0f,  3.0f, 0.0f),
                       QVector3D(-3.0f,  3.0f, 0.0f),
                       QVector3D(0.0f, -1.0f, 0.0f));
     painter->drawQuad(QVector3D(-3.0f, -3.0f, -15.0f),
                       QVector3D(-3.0f, -3.0f, 0.0f),
                       QVector3D( 3.0f, -3.0f, 0.0f),
                       QVector3D( 3.0f, -3.0f, -15.0f),
                       QVector3D(0.0f, 1.0f, 0.0f));

     mv = mv2 = mainCamera->modelViewMatrix();
     proj = mainCamera->projectionMatrix(aspectRatio);
     mv.translate(1.0f, -0.5f, 0.0f);
     mv.rotate(45.0f, 1.0f, 1.0f, 1.0f);
     painter->setMatrices(mv, proj);
     painter->setLightModel(normalModel);
     painter->selectTexturedMaterial(cubeMaterial);
     painter->setVertices(cubeVertices, 8);
     painter->setNormals(cubeVertices + 3, 8);
     painter->setTexCoords(cubeVertices + 6, 8);
     glDrawArrays(GL_TRIANGLES, 0, 36);

     mv2.translate(-0.8f, -1.5f, -3.0f);
     painter->setMatrices(mv2, proj);
     painter->selectMaterial(teapotMaterial);
 #ifdef USE_BUFFERS
     glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer);
     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
     painter->setVertices(0, 8);
     painter->setNormals(reinterpret_cast<float *>(3 * sizeof(float)), 8);
     painter->setTexCoords(reinterpret_cast<float *>(6 * sizeof(float)), 8);
     glDrawElements(GL_TRIANGLES, teapotTriangleCount * 3,
                    GL_UNSIGNED_SHORT, 0);
     glBindBuffer(GL_ARRAY_BUFFER, 0);
     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
 #else
     painter->setVertices(teapotVertexData, 8);
     painter->setNormals(teapotVertexData + 3, 8);
     painter->setTexCoords(teapotVertexData + 6, 8);
     glDrawElements(GL_TRIANGLES, teapotTriangleCount * 3,
                    GL_UNSIGNED_SHORT, teapotTriangleData);
 #endif
 }

 void View::accelerometerTimeout()
 {
     QVector3D g = gravity();
     mainCamera->setMotionAdjustment(g);
     roomCamera->setMotionAdjustment(g);
     update();
 }

 #define ACCEL_TO_G(v) (v / 9.80665)

 QVector3D View::gravity() const
 {
     qreal x = ACCEL_TO_G(sensor->reading()->x()) * sensitivity;
     qreal y = ACCEL_TO_G(sensor->reading()->y()) * sensitivity;
     qreal z = ACCEL_TO_G(sensor->reading()->z());

     return QVector3D(x, y, z);
 }