Hi, i'm trying to animate a moving arm using opengl.

i'm using update() at the end of my paintGL() function but the animation is currently too quick. is there anyway i can control the speed of the update() function?

in addition, can i know what is the difference between update() and updateGL() as my program crashes when i used updateGL() instead of update()?

Any help will be appreciated. Thanks.

Below is my code
Qt Code: 
  1. #include "mypanelopengl.h"
  2. #include <cmath>
  3.  
  4.  
  5.  
  6. MyPanelOpenGL::MyPanelOpenGL(QWidget *parent) :
  7.     QGLWidget(parent)
  8. {
  9.  
  10.     angle = 0.0;
  11.     flag = true;
  12.  
  13. }
  14.  
  15.  
  16.  
  17.  
  18. void MyPanelOpenGL::initializeGL()
  19. {
  20.     qglClearColor(Qt::white);
  21.     glShadeModel(GL_FLAT);
  22.     glEnable(GL_DEPTH_TEST);
  23.     glEnable(GL_CULL_FACE);
  24.     gluLookAt(-5,0,0,0,0,0,0,1,0);
  25. }
  26.  
  27.  
  28. void MyPanelOpenGL::resizeGL(int width, int height)
  29. {
  30.     glViewport(0, 0, width, height);
  31.     glMatrixMode(GL_PROJECTION);
  32.     glLoadIdentity();
  33.     glFrustum(-5.0, 5.0, -5.0, 5.0, -15.0, 15.0);
  34.     glOrtho(0,10,0,10,-5,5);
  35.     glMatrixMode(GL_MODELVIEW);
  36.  
  37. }
  38.  
  39. void MyPanelOpenGL::drawspine()
  40. {
  41.     glBegin(GL_LINES);
  42.  
  43.     glColor3ub(0,0,0);
  44.  
  45.     //Spine
  46.     glVertex3f(0, -5, 0);
  47.     glVertex3f(0, 5, 0);
  48.  
  49.     glEnd();
  50. }
  51.  
  52. void MyPanelOpenGL::drawshoulder()
  53. {
  54.     glBegin(GL_LINES);
  55.  
  56.     glColor3ub(0,0,0);
  57.  
  58.     //Shoulder
  59.     glVertex3f(-5, 0, 0);
  60.     glVertex3f(5, 0, 0);
  61.  
  62.     glEnd();
  63. }
  64.  
  65. void MyPanelOpenGL::drawarm()
  66. {
  67.     glBegin(GL_LINES);
  68.  
  69.     glColor3ub(0,0,0);
  70.  
  71.     //Arm
  72.     glVertex3f(-5, 0, 0);
  73.     glVertex3f(-5, -5, 0);
  74.  
  75.     glEnd();
  76.  
  77. }
  78.  
  79.  
  80. void MyPanelOpenGL::paintGL()
  81. {
  82.     glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
  83.     glLoadIdentity();
  84.     glTranslated(5.0, 5.0, 0.0);
  85.     glLineWidth(1);
  86.     glColor3f(0, 0.7f, 0.7f);
  87.  
  88.  
  89.     glRotatef(rotationY, 0.0, 1.0, 0.0);
  90.  
  91.  
  92.     drawspine();
  93.     drawshoulder();
  94.     glPushMatrix();
  95.     glRotatef(angle,1,0,0);
  96.     drawarm();
  97.     glPopMatrix();
  98.     if(flag)
  99.     {
  100.         if(angle <90)
  101.             angle++;
  102.         else
  103.             flag = false;
  104.     }
  105.     else
  106.     {
  107.         if(angle > 0)
  108.            angle--;
  109.         else
  110.             flag = true;
  111.     }
  112.  
  113.  
  114.     update();
  115.  
  116. }
  117.  
  118.  
  119.  
  120. void MyPanelOpenGL::mousePressEvent(QMouseEvent *event)
  121. {
  122.     lastPos = event->pos();
  123. }
  124.  
  125. void MyPanelOpenGL::mouseMoveEvent(QMouseEvent *event)
  126. {
  127.     GLfloat dx = GLfloat(event->x() - lastPos.x()) / width();
  128.     GLfloat dy = GLfloat(event->y() - lastPos.y()) / height();
  129.     if (event->buttons() & Qt::LeftButton) {
  130.         rotationX += 180 * dy;
  131.         rotationY += 180 * dx;
  132.         updateGL();
  133.     } else if (event->buttons() & Qt::RightButton) {
  134.         rotationX += 180 * dy;
  135.         rotationZ += 180 * dx;
  136.         updateGL();
  137.     }
  138.     lastPos = event->pos();
  139. }
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