My first attempt at a game using opengl and a little bit of sdl

#include <GL/glut.h>
#include <GL/GL.h>
#include <GL/GLU.h>
#include <SDL/SDL.h>
#include <SDL/SDL_mixer.h>
#include <iostream>

// variables for ball position, slope, if its moving 
// right / up, ****ball speed to be added****
float a = 250.0f;
float b = 250.0f;
float m = 3.0f/2.0f;
float x = a;
float y = b;
bool mvRight = true;
bool mvUp = true;

// variables for the computer's paddle position, the 
// computer's movement speed, ****paddle size to be added****
const float CPU_SPEED = 3.0f;
float pcX = 0; float pcY = 480;

// variables for the player's paddle position,
// ****movement speed, and paddle size to be added****
float plX = 0; float plY = 10;

// color values
float red = 1.0f; float green = 1.0f; float blue = 1.0f;

// the scores for player and computer
int scorePl = 0; int scorePc = 0;

// sounds
Mix_Chunk* bounce;

// mouse listener for the player's paddle
void mouse(int mx, int my){
	plX = mx;
	if(plX > 450)
		plX = 450;
}

// set up some opengl options
void init(void){
	Mix_OpenAudio(22050, MIX_DEFAULT_FORMAT, 2, 4096);
	bounce = Mix_LoadWAV("boing2.wav");

	glClearColor(0, 0, 0, 1);
	glPointSize(10.0f);

	glViewport(0, 0, 500, 500);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();

	gluOrtho2D(0, 500, 0, 500);

}

// render the ball, computer and player paddles
// and also the text showing the score
void render(void){
	glMatrixMode(GL_MODELVIEW);
	glClear(GL_COLOR_BUFFER_BIT);

	// the ball
	glColor3f(red, green, blue);
	glBegin(GL_POINTS);
		glVertex2d(x, y);
	glEnd();
	
	// player's paddle
	glColor3f(1.0f, 1.0f, 1.0f);
	glBegin(GL_QUADS);
		glVertex2d(plX, plY);
		glVertex2d(plX + 50, plY);
		glVertex2d(plX + 50, plY + 10);
		glVertex2d(plX, plY + 10);
	glEnd();

	// the computer's paddle
	glBegin(GL_QUADS);
		glVertex2d(pcX, pcY);
		glVertex2d(pcX + 50, pcY);
		glVertex2d(pcX + 50, pcY + 10);
		glVertex2d(pcX, pcY + 10);
	glEnd();

	// the scores
	glColor3f(0.25f, 0.25f, 0.25f);
	glRasterPos2f(235.0, 250.0);
	glutBitmapCharacter(GLUT_BITMAP_HELVETICA_18, '0' + scorePc);
	glRasterPos2f(250.0, 250.0);
	glutBitmapCharacter(GLUT_BITMAP_HELVETICA_18, '-');
	glRasterPos2f(265.0, 250.0);
	glutBitmapCharacter(GLUT_BITMAP_HELVETICA_18, '0' + scorePl);

	// ...swap buffers
	glutSwapBuffers();
}

// update the computer paddle's position
void updateCPU(void){
	if(x < pcX)
		pcX -= CPU_SPEED;
	else if((pcX + 50) < x)
		pcX += CPU_SPEED;
}

// game logic for the ball's movement and position
void update(void){
	
	y = (m * (x - a) + b);

	if(mvRight){				// make sure ball stays in window - right
		if(x < 500){
			x += 2.5;
		}else{
			mvRight = false;
			m *= -1; a = x;	b = y;
		}
	}	
	if(!mvRight){				// make sure ball stays in window - left
		if(x > 0){
			x -= 2.5;
		}else{
			mvRight = true;
			m *= -1; a = x; b = y;
		}
	}
	if(mvUp){					// detect computer's paddle collision
		if((y >= pcY) && (x <= pcX + 50) && (x >= pcX)){
			m *= -1; a = x; b = y;	
			mvUp = false;
			red = 1.0f; green = 0.0f; blue = 0.0f;
			scorePc++;
			Mix_PlayChannel(-1, bounce, 0);
		}
		if(y >= 500){			// make sure ball stays in window - top
			m *= -1; a = x; b = y;
			mvUp = false;
			if(scorePc > 0)
				scorePc--;
		}
	}
	if(!mvUp){					// detect player paddle collision
		if((y <= plY + 10) && (x <= plX + 50) && (x >= plX)){
			m *= -1; a = x; b = y;
			mvUp = true;
			red = 0.0f; green = 1.0f; blue = 0.0f;
			scorePl++;
			Mix_PlayChannel(-1, bounce, 0);
		}
		if(y <= 0){				// make sure ball stays in window - bottom
			m*= -1; a = x; b = y;
			mvUp = true;
			if(scorePl > 0)
				scorePl--;
		}
	}

	updateCPU();				// update the computer paddle's position
	render();					// render everything
}

// callback for when window gets reshaped
void reshape(int width, int height){
	glViewport(0, 0, (GLsizei)width, (GLsizei)height);
	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	gluOrtho2D(0, 500, 0, 500);

	glMatrixMode(GL_MODELVIEW);
}

// for animation around 60 fps
void timer(int iUnused){
	glutPostRedisplay();
	glutTimerFunc(16, timer, 0); // call itself every 12 ms
}

// application entry point - create window, set up some opengl 
// options and set up callbacks for mouse listener, 
// window resizing, and the main game loop
int main(int argc, char **argv){
	glutInit(&argc, argv);			// create the window and set some options
	glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE);
	glutInitWindowSize(500, 500);
	glutInitWindowPosition(100, 100);
	glutCreateWindow("Pong in OpenGL ... sort of");
	
	init();							// set some rendering options and setup audio
	glutDisplayFunc(update);		// set the function for display callback
	glutReshapeFunc(reshape);		// set the function for reshape callback
	timer(0);						// setup a timer to refresh the canvas (every 12 ms, roughly 60 fps)
	glutPassiveMotionFunc(mouse);	// set the function for mouse movement callback

	glutMainLoop();					// start the gl main loop 

	Mix_FreeChunk(bounce);			// do some cleaning up
	Mix_CloseAudio();
	SDL_Quit();

	exit(0);
}