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suriogl
12-10-2008, 05:27 AM
I have this program which draws cube on the boundary of the defined ortho. I see that the line on the left and top are missing. What could be the problem? The code snippet is pasted below:

#include <GL/glut.h>

void init(void)
{
glClearColor (0.0, 0.0, 0.0, 0.0);
glShadeModel (GL_FLAT);

}

void display(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glLoadIdentity (); /* clear the matrix */

glBegin( GL_LINE_LOOP );
glColor4f (1.0, 0.0, 0.0,1.0);
glVertex2f( -1.0f, -1.0f);
glVertex2f( -1.0f, 1.0f);
glVertex2f( 1.0f,1.0f);
glVertex2f( 1.0f, -1.0f);
glEnd( );
glFlush ();
}

void reshape (int w, int h)
{
glViewport (0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode (GL_PROJECTION);
glLoadIdentity ();
glOrtho (-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);

glMatrixMode (GL_MODELVIEW);
glLoadIdentity ();
}


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

glutInit(&argc, argv);
glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
glutInitWindowSize (500, 500);
glutInitWindowPosition (100, 100);
glutCreateWindow (argv[0]);
init ();
glutDisplayFunc(display);
glutReshapeFunc(reshape);

glutMainLoop();
return 0;
}

_NK47
12-10-2008, 06:49 AM
you draw a rectangle not a cube. LINE_LOOP should connect to first vertex on glEnd() so looks ok. try drawing it in the center and make sure its displayed correct as it might be clipped.