Xcode begginer issues

OpenGL OpenGL: Basic Coding
1

Hi, I am following the popular NeHe tutorials, currently in Lesson 5, where I have a problem, the Objects are not rendering properly, here is my code:

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

GLfloat rtri;
GLfloat rquad;


void init (void) {
	glShadeModel(GL_SMOOTH);
	glClearColor(0.0, 0.0, 0.0, 0.0);
	glClearDepth(1.0);
	glEnable(GL_DEPTH_TEST);
	glDepthFunc(GL_LEQUAL);
	glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
}


void display(void) {
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
	
	/* piramid */
	glTranslatef(-1.5, 0.0, -6.0);
	glRotatef(rtri, 0.0, 1.0, 0.0);
	
	glBegin(GL_TRIANGLES);
	
	glColor3f(1.0, 0.0, 0.0);
	glVertex3f( 0.0,  1.0, 0.0);
	glColor3f(0.0, 1.0, 0.0);
	glVertex3f(-1.0, -1.0, 1.0);
	glColor3f(0.0, 0.0, 1.0);
	glVertex3f( 1.0, -1.0, 1.0);
	
	glColor3f(1.0, 0.0, 0.0);
	glVertex3f( 0.0,  1.0, 0.0);
	glColor3f(0.0, 0.0, 1.0);
	glVertex3f( 1.0, -1.0, 1.0);
	glColor3f(0.0, 1.0, 0.0);
	glVertex3f( 1.0, -1.0, -1.0);
	
	glColor3f(1.0, 0.0, 0.0);
	glVertex3f( 0.0,  1.0, 0.0);
	glColor3f(0.0, 1.0, 0.0);
	glVertex3f( 1.0, -1.0, -1.0);
	glColor3f(0.0, 0.0, 1.0);
	glVertex3f(-1.0, -1.0, -1.0);
	
	glColor3f(1.0, 0.0, 0.0);
	glVertex3f( 0.0,  1.0, 0.0);
	glColor3f(0.0, 0.0, 1.0);
	glVertex3f(-1.0, -1.0, -1.0);
	glColor3f(0.0, 1.0, 0.0);
	glVertex3f(-1.0, -1.0, 1.0);
	
	glEnd();
	
	
	
	glLoadIdentity();
	
	/* box */
	glTranslatef(1.5, 0.0, -6.0);
	glRotatef(rquad, 0.0, 1.0, 0.0);
	
	glBegin(GL_QUADS);
	
	glColor3f(0.0, 1.0, 0.0);
	glVertex3f( 1.0,  1.0, -1.0);
	glVertex3f(-1.0,  1.0, -1.0);
	glVertex3f(-1.0,  1.0,  1.0);
	glVertex3f( 1.0,  1.0,  1.0);
	
	glColor3f(1.0, 0.5, 0.0);
	glVertex3f( 1.0, -1.0,  1.0);
	glVertex3f(-1.0, -1.0,  1.0);
	glVertex3f(-1.0, -1.0, -1.0);
	glVertex3f( 1.0, -1.0, -1.0);
	
	glColor3f(1.0, 0.0, 0.0);
	glVertex3f( 1.0,  1.0,  1.0);
	glVertex3f(-1.0,  1.0,  1.0);
	glVertex3f(-1.0, -1.0,  1.0);
	glVertex3f( 1.0, -1.0,  1.0);
		
	glColor3f(1.0, 1.0, 0.0);
	glVertex3f( 1.0, -1.0, -1.0);
	glVertex3f(-1.0, -1.0, -1.0);
	glVertex3f(-1.0,  1.0, -1.0);
	glVertex3f( 1.0,  1.0, -1.0);
	
	glColor3f(0.0, 0.0, 1.0);
	glVertex3f(-1.0,  1.0,  1.0);
	glVertex3f(-1.0,  1.0, -1.0);
	glVertex3f(-1.0, -1.0, -1.0);
	glVertex3f(-1.0, -1.0,  1.0);
	
	glColor3f(1.0, 0.0, 1.0);
	glVertex3f( 1.0,  1.0, -1.0);
	glVertex3f( 1.0,  1.0,  1.0);
	glVertex3f( 1.0, -1.0,  1.0);
	glVertex3f( 1.0, -1.0, -1.0);
	
	glEnd();
	
	rtri += 0.02;
	rquad -= 0.015;
	
	glutSwapBuffers();
	glutPostRedisplay();
}



void reshape(int w, int h) {
	glViewport(0, 0, (GLsizei)w, (GLsizei)h);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluPerspective(45.0, (GLfloat)w / (GLfloat)h, 0.1, 100.0);
	glMatrixMode(GL_MODELVIEW);
	glLoadIdentity();
}



int main(int argc, char** argv) {
	/* creates a new window and its attributes */
	glutInit(&argc, argv);
	glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
	glutInitWindowSize(450, 350);
	glutInitWindowPosition(400, 300);
	//glutCreateWindow("learning opengl");
	glutCreateWindow(argv[0]);
	
	init ();
	/* drawing */
	glutDisplayFunc(display);
	/* resize */
	glutReshapeFunc(reshape);
	glutMainLoop();
	return 0;
}

for some reason the last vertex points appear always in front making the geometry to look odd, so what I need to do to fix this? also, If I comment the init() function it does not make any difference?

Cheers
rS

2

You enabled depth testing, but that alone is not enough to ensure that the testing works. You also need a depth buffer in which to store depth values. add GLUT_DEPTH to the glutInitDisplayMode argument and then it should work fine.

3

It works!

Now is it the code for the animation the best way to do it or is it a better way?

Thanks
rS

4

Well, this works, so this is fine. There is a glutTimerFunc that calls a function after a certain amount of time, so you can use that to control the framerate if you want. For large [projects, you’ll probably use something other than GLUT, so you’ll do it with that.