CODEWITHSUNDEEP
openglrendering
iyl
iyl

Reputation: 13

Edward Angel example OpenGL code: runs fine on Lenovo X60, but does not render windows on my desktop (Intel HD Graphics)

I'm new to OpenGL and trying to run some classic sample code from Edward Angel's famous book Interactive Computer Graphics. However, I've encountered a problem which puzzles me a lot but is probably very obvious to many others. The sample code is "Gasket.c" which can be downloaded from http://www.cs.unm.edu/~angel/BOOK/INTERACTIVE_COMPUTER_GRAPHICS/FIFTH_EDITION/PROGRAMS/CHAPTER02/

I've run this code with VS2010 Express on my Lenovo X60 (windows 7) and it has successfully drawn Sierspinski Gasket. However, it did not draw anything and only showed a blank (white) window when I was trying to run the same code on my desktop (Intel HD Graphics card) with same software systems. The file was complied/built with no problems and there were no errors/warnings.

Gasket.c is as follows

/* Two-Dimensional Sierpinski Gasket          */
/* Generated Using Randomly Selected Vertices */
/* And Bisection                              */

#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif

void myinit()
{

/* attributes */

     glClearColor(1.0, 1.0, 1.0, 1.0); /* white background */
     glColor3f(1.0, 0.0, 0.0); /* draw in red */

/* set up viewing */
/* 500 x 500 window with origin lower left */

     glMatrixMode(GL_PROJECTION);
     glLoadIdentity();
     gluOrtho2D(0.0, 50.0, 0.0, 50.0);
     glMatrixMode(GL_MODELVIEW);
}

void display( void )
{
    GLfloat vertices[3][2]={{0.0,0.0},{25.0,50.0},{50.0,0.0}}; /* A triangle */

    int j, k;
    int rand();       /* standard random number generator */
    GLfloat p[2] ={7.5,5.0};  /* An arbitrary initial point inside traingle */

    glClear(GL_COLOR_BUFFER_BIT);  /*clear the window */


/* compute and plots 5000 new points */

        glBegin(GL_POINTS);

    for( k=0; k<5000; k++)
    {
         j=rand()%3; /* pick a vertex at random */


     /* Compute point halfway between selected vertex and old point */

         p[0] = (p[0]+vertices[j][0])/2.0; 
         p[1] = (p[1]+vertices[j][1])/2.0;

     /* plot new point */

        glVertex2fv(p); 

     }
     glEnd();
     glFlush(); /* clear buffers */
   }

void main(int argc, char** argv)
{

/* Standard GLUT initialization */

    glutInit(&argc,argv);
    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB); /* default, not needed */
    glutInitWindowSize(500,500); /* 500 x 500 pixel window */
    glutInitWindowPosition(0,0); /* place window top left on display */
    glutCreateWindow("Sierpinski Gasket"); /* window title */
    glutDisplayFunc(display); /* display callback invoked when window opened */

    myinit(); /* set attributes */

    glutMainLoop(); /* enter event loop */
}

Upvotes: 1

Views: 842

Answers (1)

genpfault
genpfault

Reputation: 52167

Try switching from single-buffering (GLUT_SINGLE) to double-buffering (GLUT_DOUBLE):

#include <GL/glut.h>

void display( void )
{
    GLfloat vertices[3][2]={{0.0,0.0},{25.0,50.0},{50.0,0.0}}; /* A triangle */

    int j, k;
    int rand();       /* standard random number generator */
    GLfloat p[2] ={7.5,5.0};  /* An arbitrary initial point inside traingle */

    glClearColor(1.0, 1.0, 1.0, 1.0); /* white background */
    glClear(GL_COLOR_BUFFER_BIT);  /*clear the window */

    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();

    gluOrtho2D(0.0, 50.0, 0.0, 50.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    /* compute and plots 5000 new points */
    glColor3f(1.0, 0.0, 0.0); /* draw in red */
    glBegin(GL_POINTS);
    for( k=0; k<5000; k++)
    {
        j=rand()%3; /* pick a vertex at random */

        /* Compute point halfway between selected vertex and old point */
        p[0] = (p[0]+vertices[j][0])/2.0; 
        p[1] = (p[1]+vertices[j][1])/2.0;

        /* plot new point */
        glVertex2fv(p); 

    }
    glEnd();

    glutSwapBuffers();
}

void main(int argc, char** argv)
{
    glutInit(&argc,argv);
    glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB); /* default, not needed */
    glutInitWindowSize(500,500); /* 500 x 500 pixel window */
    glutInitWindowPosition(0,0); /* place window top left on display */
    glutCreateWindow("Sierpinski Gasket"); /* window title */
    glutDisplayFunc(display); /* display callback invoked when window opened */
    glutMainLoop(); /* enter event loop */
}

Upvotes: 1

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