qt/sphere-quadstrips/myglwidget.cpp

   1 #include <iostream>
   2 #include <QKeyEvent>
   3 #include <QtOpenGL>
   4
   5 #include <cmath>
   6 #include "myglwidget.h"
   7
   8 MyGLWidget::MyGLWidget(QWidget *parent)
   9     : QGLWidget(parent)
  10 {
  11     std::cout << "GLWidget() constructor\n";
  12
  13     numVertices = 10;
  14
  15     xRot = 0.0f;
  16     yRot = 0.0f;
  17     zRot = 0.0f;
  18
  19     this->setMinimumWidth(300);
  20     this->setMinimumHeight(300);
  21 }
  22
  23 MyGLWidget::~MyGLWidget()
  24 {
  25     std::cout << "~GLWidget() deconstructor\n";
  26 }
  27
  28 void MyGLWidget::setNumOfVertices(int dir)
  29 {
  30     std::cout << "myglWidget::setNumOfVertices()" << std::endl;
  31
  32     numVertices += dir;
  33     if (numVertices > 2) {
  34         makeCurrent();
  35         glClear(GL_COLOR_BUFFER_BIT);
  36         drawSphere(10, 10, 0.5f);
  37         updateGL();
  38     }
  39     else
  40         numVertices = 2;
  41 }
  42
  43 void MyGLWidget::rotateX(GLfloat angle)
  44 {
  45     std::cout << "MyGLWidget::rotateX()\n";
  46
  47     xRot += angle;
  48     updateGL();
  49 }
  50
  51 void MyGLWidget::rotateY(GLfloat angle)
  52 {
  53     std::cout << "MyGLWidget::rotateY()\n";
  54
  55     yRot += angle;
  56     updateGL();
  57 }
  58
  59 void MyGLWidget::rotateZ(GLfloat angle)
  60 {
  61     std::cout << "MyGLWidget::rotateZ()\n";
  62
  63     zRot += angle;
  64     updateGL();
  65 }
  66
  67 void MyGLWidget::initializeGL()
  68 {
  69     std::cout << "MyGLWidget::initializeGL()\n";
  70
  71     // Enable backface culling
  72     glEnable(GL_CULL_FACE);
  73
  74     // Clear color is set to black
  75     glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
  76     glShadeModel(GL_SMOOTH);
  77
  78     // Reset modelview matrix
  79     glMatrixMode(GL_MODELVIEW);
  80     glLoadIdentity();
  81
  82     // We don't need to call drawSphere() here,
  83     // since the resizeGL() will be called upon
  84     // the initial creation of the window.
  85 }
  86
  87 void MyGLWidget::paintGL()
  88 {
  89     std::cout << "paintGL()\n";
  90
  91     // Clear scene
  92     glClear(GL_COLOR_BUFFER_BIT);
  93
  94     // Reset modelview matrix
  95     glMatrixMode(GL_MODELVIEW);
  96     glLoadIdentity();
  97
  98     // Rotate appropriately
  99     glRotatef(xRot, 1.0f, 0.0f, 0.0f);
 100     glRotatef(yRot, 0.0f, 1.0f, 0.0f);
 101     glRotatef(zRot, 0.0f, 0.0f, 1.0f);
 102
 103     // Draw x, y, z axis
 104     drawAxis();
 105
 106     // Draw sphere
 107     drawSphere(10, 10, 0.5f);
 108
 109     glFlush();
 110 }
 111
 112 void MyGLWidget::resizeGL(int width, int height)
 113 {
 114     std::cout << "MyGLWidget::resizeGL()\n";
 115     std::cout << "New width = " << width
 116               << "\nNew height = " << height << "\n";
 117
 118     // Update viewport to cover the whole screen
 119     glViewport(0, 0, width, height);
 120
 121     // Reset projection matrix
 122     glMatrixMode(GL_PROJECTION);
 123     glLoadIdentity();
 124     //gluPerspective(45.0, (GLfloat)width/(GLfloat)height, 0.1f, 100.0f);
 125
 126     // Reset modelview matrix
 127     glMatrixMode(GL_MODELVIEW);
 128     glLoadIdentity();
 129 }
 130
 131 void MyGLWidget::drawAxis(void)
 132 {
 133     // Draw axis
 134     glLineWidth(3);
 135     glEnable(GL_LINE_SMOOTH);
 136     glColor3f(0.0f, 1.0f, 0.0f);
 137
 138     glBegin(GL_LINES);
 139         glVertex3f(0.0f, 0.0f, 0.0f);    // x axis
 140         glVertex3f(1.0f, 0.0f, 0.0f);
 141
 142         glVertex3f(0.0f, 0.0f, 0.0f);    // y axis
 143         glVertex3f(0.0f, 1.0f, 0.0f);
 144
 145         glVertex3f(0.0f, 0.0f, 0.0f);    // z axis
 146         glVertex3f(0.0f, 0.0f, 1.0f);
 147     glEnd();
 148
 149     // Restore color and line width
 150     glColor3f(1.0f, 1.0f, 1.0f);
 151     glDisable(GL_LINE_SMOOTH);
 152     glLineWidth(1);
 153 }
 154
 155 void MyGLWidget::drawSphere(GLuint nStacks, GLuint nSlices, GLfloat r)
 156 {
 157     GLfloat theta, phi, x, y, z, stepTheta, stepPhi;
 158
 159     stepTheta = M_PI / nStacks;
 160     stepPhi = 2 * M_PI / nSlices;
 161
 162     for (theta = 0; theta <= M_PI; theta += stepTheta) {
 163         glBegin(GL_QUAD_STRIP);
 164         for (phi = 0; phi <= 2.0 * M_PI; phi += stepPhi) {
 165             x = r * sin(theta) * cos(phi);
 166             y = r * sin(theta) * sin(phi);
 167             z = r * cos(theta);
 168             glVertex3f(x, y, z);
 169
 170             x = r * sin(theta + stepTheta) * cos(phi);
 171             y = r * sin(theta + stepTheta) * sin(phi);
 172             z = r * cos(theta + stepTheta);
 173             glVertex3f(x, y, z);
 174         }
 175         glEnd();
 176     }
 177
 178     // The boundary edges of the polygon are drawn as line segments.
 179     glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
 180 }