Chapter-1-Compatibility.c

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <GL/glew.h>
#include <GL/freeglut.h>
#define WINDOW_TITLE_PREFIX "Chapter 1"

int CurrentWidth = 800,
	CurrentHeight = 600,
	WindowHandle = 0;

unsigned FrameCount = 0;

void Initialize(int, char*[]);
void InitWindow(int, char*[]);
void ResizeFunction(int, int);
void RenderFunction(void);
void TimerFunction(int);
void IdleFunction(void);

int main(int argc, char* argv[])
{
	Initialize(argc, argv);

	glutMainLoop();
	
	exit(EXIT_SUCCESS);
}

void Initialize(int argc, char* argv[])
{
	GLenum GlewInitResult;

	InitWindow(argc, argv);

	GlewInitResult = glewInit();

	if (GLEW_OK != GlewInitResult) {
		fprintf(
			stderr,
			"ERROR: %s\n",
			glewGetErrorString(GlewInitResult)
		);
		exit(EXIT_FAILURE);
	}
	
	fprintf(
		stdout,
		"INFO: OpenGL Version: %s\n",
		glGetString(GL_VERSION)
	);

	glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
}

void InitWindow(int argc, char* argv[])
{
	glutInit(&argc, argv);
	
	glutInitContextVersion(3, 3);
	glutInitContextFlags(GLUT_FORWARD_COMPATIBLE);
	glutInitContextProfile(GLUT_CORE_PROFILE);

	glutSetOption(
		GLUT_ACTION_ON_WINDOW_CLOSE,
		GLUT_ACTION_GLUTMAINLOOP_RETURNS
	);
	
	glutInitWindowSize(CurrentWidth, CurrentHeight);

	glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);

	WindowHandle = glutCreateWindow(WINDOW_TITLE_PREFIX);

	if(WindowHandle < 1) {
		fprintf(
			stderr,
			"ERROR: Could not create a new rendering window.\n"
		);
		exit(EXIT_FAILURE);
	}
	
	glutReshapeFunc(ResizeFunction);
	glutDisplayFunc(RenderFunction);
	glutIdleFunc(IdleFunction);
	glutTimerFunc(0, TimerFunction, 0);
}

void ResizeFunction(int Width, int Height)
{
	CurrentWidth = Width;
	CurrentHeight = Height;
	glViewport(0, 0, CurrentWidth, CurrentHeight);
}

void RenderFunction(void)
{
	++FrameCount;

	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

	glutSwapBuffers();
	glutPostRedisplay();
}

void IdleFunction(void)
{
	glutPostRedisplay();
}

void TimerFunction(int Value)
{
	if (0 != Value) {
		char* TempString = (char*)
			malloc(512 + strlen(WINDOW_TITLE_PREFIX));

		sprintf(
			TempString,
			"%s: %d Frames Per Second @ %d x %d",
			WINDOW_TITLE_PREFIX,
			FrameCount * 4,
			CurrentWidth,
			CurrentHeight
		);

		glutSetWindowTitle(TempString);
		free(TempString);
	}
	
	FrameCount = 0;
	glutTimerFunc(250, TimerFunction, 1);
}