Troubleshooting OpenGL+GLUT on OSX

[cscott]

I'm having some trouble on OS X following a tutorial that wasn't really meant for this language-OS combination.

I'm using Xcode and the GLUT+OpenGL frameworks to compile the following code. [it's supposed to open a window and display a white square and triangle on a black backdrop.]:

#include <OpenGL/gl.h>		
#include <OpenGL/glu.h>		
#include <GLUT/glut.h>		

#define kWindowWidth	800
#define kWindowHeight	300

GLvoid InitGL(GLvoid);
GLvoid DrawGLScene(GLvoid);
GLvoid ReSizeGLScene(int Width, int Height);

int main(int argc, char** argv)
{
	glutInit(&argc, argv);
	glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
	glutInitWindowSize (kWindowWidth, kWindowHeight);
	glutInitWindowPosition (100, 100);
	glutCreateWindow (argv[0]);

	InitGL();

	glutDisplayFunc(DrawGLScene);
	glutReshapeFunc(ReSizeGLScene);

	glutMainLoop();

	return 0;
}

GLvoid ReSizeGLScene(int width, int height)				// Resize And Initialize The GL Window
{
	if (height==0)								// Prevent A Divide By Zero By
	{
		height=1;							// Making Height Equal One
	}

	glViewport(0, 0, width, height);	
		glMatrixMode(GL_PROJECTION);						// Select The Projection Matrix
	glLoadIdentity();							// Reset The Projection Matrix

	// Calculate The Aspect Ratio Of The Window
	gluPerspective(45.0f,(GLfloat)width/(GLfloat)height,0.1f,100.0f);

	glMatrixMode(GL_MODELVIEW);						// Select The Modelview Matrix
	glLoadIdentity();							// Reset The Modelview Matrix
}

GLvoid InitGL(GLvoid)								// All Setup For OpenGL Goes Here
{
	glShadeModel(GL_SMOOTH);						
	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);		
	glClearDepth(1.0f);							// Depth Buffer Setup
	glEnable(GL_DEPTH_TEST);						// Enables Depth Testing
	glDepthFunc(GL_LEQUAL);	
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);	
 }
 
GLvoid DrawGLScene(GLvoid)								// Here's Where We Do All The Drawing
{
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);		// Clear The Screen And The Depth Buffer
	glLoadIdentity();	
	glTranslatef(-1.5f,0.0f,-6.0f);		
	
	glBegin(GL_TRIANGLES);						// Drawing Using Triangles
		glVertex3f( 0.0f, 1.0f, 0.0f);				// Top
		glVertex3f(-1.0f,-1.0f, 0.0f);				// Bottom Left
		glVertex3f( 1.0f,-1.0f, 0.0f);				// Bottom Right
	glEnd();							// Finished Drawing The Triangle

	glBegin(GL_QUADS);						// Draw A Quad
		glVertex3f(-1.0f, 1.0f, 0.0f);				// Top Left
		glVertex3f( 1.0f, 1.0f, 0.0f);				// Top Right
		glVertex3f( 1.0f,-1.0f, 0.0f);				// Bottom Right
		glVertex3f(-1.0f,-1.0f, 0.0f);				// Bottom Left
	glEnd();							// Done Drawing The Quad
}

...I get a window but it's white with nothing in it. When I resize the window to particular sizes I can see the black background and square only but obviously something is still wrong...

The only code I can find is written in Objective-C and uses some NextStep stuff.

NeHe tutotirlas:
http://nehe.gamedev.net/data/lessons/lesson.asp?lesson=02
http://nehe.gamedev.net/data/lessons/lesson.asp?lesson=Mac_OS_X

 

[Four]

For the DrawGLScene(GLvoid) before the glBegin(...) commands put glColor3f(1.0, 1.0, 1.0). You might want to change the colors if you feel like.

However I didn't find a resonable sollution yet. I didn't find what may be wrong yet too. You can try that and see if it works though.

 

[Four]

Haha I found it. I don't know why I didn't notice. At the end of the redraw function DrawGLScene(GLvoid) add glutSwapBuffers(). and you might also want the glColorf() too. Hope that works. I didn't look at the tutorial yet, I trust you copyed and pasted the code correctly.

 

[cscott]

Thanks a lot, it works now.

I was actually missing a translate command too, so that the square and triangle weren't on top of each other.