# OpenGL OpenGL and Xcode

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Hi, I'm trying to get OpenGL code I wrote at university to compile and run at home, on my Mac. I'm using Xcode, and followed a tutorial (this one: http://www.onesadcookie.com/Tutorials/) to try and set up Xcode so I would be able to do this. I used the example code given in that tutorial, and when i run it, it draws a black screen, even when i have added the code that comes later on in that tutorial (that should draw a white square). I added the Cocoa.framework, GLUT.framework, and OpenGL.framework to my project (as described in the tutorial), and i'm really stuck as to why it doesnt draw anything when the window opens.. If anyone's got any ideas i'd realy love to hear them, as i'm stuck..! Thanks for reading, ask me if i've missed out any information that you might need to know! Cheers! Jon

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- are matrices properly set up?
- use glGetError
- put a glutSolidCube into display - maybe this helps you to find the quad ;-)
- post your code

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As the poster above suggested, you'll probably need to provide some more info. onesadcookie knows his stuff with respect to OS X though, so I doubt the problem lies with his tutorial.

You could also post this over at idevgames.com, which onesadcookie frequents.

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Hi there, thanks for your replies!

I tried putting a solid cube in, but it didnt fix it. And i'm not sure how to use glGetError? But here is my code:

#include <stdlib.h>

#include <GLUT/glut.h>

void display(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glBegin(GL_QUADS);
glColor3f (1.0, 1.0, 1.0);
glVertex2f(-0.75f, -0.75f);
glVertex2f( 0.75f, -0.75f);
glVertex2f( 0.75f, 0.75f);
glVertex2f(-0.75f, 0.75f);
glEnd();

glutSwapBuffers();
}

void reshape(int width, int height)
{
glViewport(0, 0, width, height);
}

void idle(void)
{
glutPostRedisplay();
}

int main(int argc, char** argv)
{
glutInit(&argc, argv);

glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH);
glutInitWindowSize(640, 480);

glutCreateWindow("GLUT Program");

glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutIdleFunc(idle);

glutMainLoop();
return EXIT_SUCCESS;
}

Its the code thats shown on the tutorial by onesadcookie. I'll go onto the site that he frequents if all else fails!

I'm sure his tutorial works, it worked for someone i know, i guess i must have just missed something.. but its pretty hard to know what, i went through it again a few times and had no joy.

Any help is greatly appreciated! :)

thanks!
jon

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Try setting up an orthographic projection in your reshape function, like so:

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();

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Hi again,

I popped that in the reshape function, but it didnt chnage anything.. It's really bizarre, especially given the code is code from that tutorial and i'm sure is faultless. A window does open saying 'GLUT window' and its completely black.
Any other ideas? Thanks a lot for your help :)

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Did you associate opengl, glut, and cocoa frameworks? You shouldn't need anything else.

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Email OSC or goto idevgames where OSC hangs out at. He is more than willing to answer your questions.

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