OpenGL code Works in Windows but not Mac - c++

Question

My school uses windows computers but I only have a mac at home.
The code runs fine in windows but for some reason I get errors running it in xCode.
I wasn't sure which frameworks to include so I added GLKit, Cocoa, GLUT, and OpenGL.
Am I missing something??
I would like to get Xcode setup so I can work on homework with the same code that will work on windows.
Here is the code
#include <stdio.h>
#include <stdarg.h>
#include <math.h>
#define GL_GLEXT_PROTOTYPES
#ifdef __APPLE__
#include <GLUT/glut.h>
#else
#include <GL/glut.h>
#endif
#define GLUT_KEY_ESCAPE 27
const GLsizei windowWidth = 500;
const GLsizei windowHeight = 500;
GLfloat cubeRotateX = 45.0f;
GLfloat cubeRotateY = 45.0f;
bool keys[255];
GLvoid establishProjectionMatrix(GLsizei width, GLsizei height)
{
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(45.0f, (GLfloat)width / (GLfloat)height, 0.1f, 200.0f);
}
GLvoid initGL(GLsizei width, GLsizei height)
{
establishProjectionMatrix(width, height);
glShadeModel(GL_SMOOTH);
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
glEnable(GL_PERSPECTIVE_CORRECTION_HINT);
}
GLvoid displayFPS(GLvoid)
{
static long lastTime = glutGet(GLUT_ELAPSED_TIME);
static int loops = 0;
static GLfloat fps = 0.0f;
int newTime = glutGet(GLUT_ELAPSED_TIME);
if (newTime - lastTime > 100)
{
float newFPS = (float)loops / float(newTime - lastTime) * 1000.0f;
fps = (fps + newFPS) / 2.0f;
char title[80];
sprintf_s(title, "OpenGL Demo - %.2f", fps);
glutSetWindowTitle(title);
lastTime = newTime;
loops = 0;
}
loops++;
}
GLvoid drawScene(GLvoid)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glTranslatef(0, 0, -5.0f);
glRotatef(cubeRotateX, 1.0, 0.0, 0.0);
glRotatef(cubeRotateY, 0.0, 1.0, 0.0);
glBegin(GL_QUADS);
glColor3f(0.0f, 1.0f, 1.0f);
glVertex3f( 1.0f, 1.0f, -1.0f);
glVertex3f(-1.0f, 1.0f, -1.0f);
glVertex3f(-1.0f, 1.0f, 1.0f);
glVertex3f( 1.0f, 1.0f, 1.0f);
glColor3f(0.0f, 1.0f, 0.0f);
glVertex3f( 1.0f, -1.0f, -1.0f);
glVertex3f(-1.0f, -1.0f, -1.0f);
glVertex3f(-1.0f, -1.0f, 1.0f);
glVertex3f( 1.0f, -1.0f, 1.0f);
glColor3f(1.0f, 0.0f, 0.0f);
glVertex3f( 1.0f, 1.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 1.0f);
glVertex3f(-1.0f, -1.0f, 1.0f);
glVertex3f( 1.0f, -1.0f, 1.0f);
glColor3f(1.0f, 1.0f, 0.0f);
glVertex3f( 1.0f, 1.0f, -1.0f);
glVertex3f(-1.0f, 1.0f, -1.0f);
glVertex3f(-1.0f, -1.0f, -1.0f);
glVertex3f( 1.0f, -1.0f, -1.0f);
glColor3f(0.0f, 0.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, 1.0f);
glVertex3f(-1.0f, 1.0f, -1.0f);
glVertex3f(-1.0f, -1.0f, -1.0f);
glVertex3f(-1.0f, -1.0f, 1.0f);
glColor3f(1.0f, 0.0f, 1.0f);
glVertex3f( 1.0f, 1.0f, 1.0f);
glVertex3f( 1.0f, 1.0f, -1.0f);
glVertex3f( 1.0f, -1.0f, -1.0f);
glVertex3f( 1.0f, -1.0f, 1.0f);
glEnd();
glFlush();
glutSwapBuffers();
displayFPS();
}
GLboolean checkKeys(GLvoid)
{
const GLfloat speed = 1.0f;
if ( keys[GLUT_KEY_ESCAPE] )
return true;
if (keys[GLUT_KEY_LEFT])
cubeRotateY -= speed;
if (keys[GLUT_KEY_RIGHT])
cubeRotateY += speed;
if (keys[GLUT_KEY_UP])
cubeRotateX -= speed;
if (keys[GLUT_KEY_DOWN])
cubeRotateX += speed;
return false;
}
GLvoid timerLoop(int value)
{
if (checkKeys())
exit(0);
glutPostRedisplay();
glutTimerFunc(1, timerLoop, 0);
}
GLvoid keyboardCB(unsigned char key, int x, int y)
{
keys[key] = true;
}
GLvoid keyboardUpCB(unsigned char key, int x, int y)
{
keys[key] = false;
}
GLvoid keyboardSpecialCB(int key, int x, int y)
{
keys[key] = true;
}
GLvoid keyboardSpecialUpCB(int key, int x, int y)
{
keys[key] = false;
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE);
int windowID = glutCreateWindow("OpenGL Cube Demo");
glutReshapeWindow(windowWidth, windowHeight);
initGL(windowWidth, windowHeight);
glutDisplayFunc(drawScene);
glutKeyboardFunc(keyboardCB);
glutKeyboardUpFunc(keyboardUpCB);
glutSpecialFunc(keyboardSpecialCB);
glutSpecialUpFunc(keyboardSpecialUpCB);
glutTimerFunc(1, timerLoop, 0);
glutMainLoop();
return 0;
}
Why does it work in visual studio and not in Xcode??

Answer 1

The errors from the compiler seem pretty clear. The superficial reason it doesn't work is because this code contains Windows-isms that are not portable.
C++ doesn't allow a typedef of void to indicate an empty parameter list. You have to use void itself. So, just changed those GLvoids to voids.
sprintf_s() is a Windows-specific function. You can replace it with snprintf(), but you have to add a parameter after the buffer which is the size of the buffer. So, replace this:
sprintf_s(title, ...);
with:
snprintf(title, sizeof(title), ...);
The exit() function is available cross-platform, but you have to include the right header. Add #include <stdlib.h> near the top of your file.