a newbie question about GLUT

[tomy]

Hi guys, I've just started learning OpenGL and I just wrote a very simple program that draws a triangle. The problem is that if I use GLUT_DOUBLE instead of GLUT_SINGLE in glutInitDisplayMode(), nothing shows up in the window. I don't know why that is and that's why I'm posting here. I don't quite understand the difference between GLUT_SINGLE and GLUT_DOUBLE.

here's my code:

void draw()
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	glBegin(GL_TRIANGLES);
	glVertex3f(0,1,0);
	glVertex3f(.5,0,0);
	glVertex3f(1,1,0);
	glEnd();
	glFlush();
}

int main(int argc, char** argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA | GLUT_DEPTH);  // <--- if I change the GLUT_SINGLE to GLUT_DOUBLE then nothing shows up
	glutInitWindowSize(400, 400);
    glutInitWindowPosition(100,100);
	glutCreateWindow("Testing");
	glutDisplayFunc(draw);
	
	glutMainLoop();
	return 0;
	
}

Any help would be greatly appreciated, thank you!

[scwizzo]

I think you need glutSwapBuffers(); in your draw function. Put it at the end.