A Basic 3D Asteroid Game in openGL with C#

• Download source - 2.7 MB

Introduction

This article is intended for beginners who want to start with 3D game programming and don’t know where to start. It is programmed in OpenGL using VS 2008 and a small graphic engine I made myself called Shadowengine. It has the basics of what a game should have: a Score, levels of difficulty and a life counter. All this is written in a small number of code lines, with the objective of being simple and understandable.

The first problem I had to achieve is the scene to look like outer space. For that issue, I set the background color to black. In OpenGL, it is set this way:

Gl.glClearColor(0, 0, 0, 1);//red green blue alpha 

The other problem was the stars and I solve it by drawing random white points on the screen. The algorithm is more or less this way. I generate a random point and measure the distance to the spaceship, and if it is less than a predefined number, I discard it and repeat the process until it creates the desired stars. Look at the code:

public void CreateStars(int cantidad)
        {
            Random r = new Random();
            int count = 0;
            while (count != cantidad)
            {
                Position p = default(Position);
                p.x = (r.Next(110)) * (float)Math.Pow(-1, r.Next());
                p.z = (r.Next(110)) * (float)Math.Pow(-1, r.Next());
                p.y = (r.Next(110)) * (float)Math.Pow(-1, r.Next());
                if (Math.Pow(Math.Pow(p.x, 2) + Math.Pow(p.y, 2) +
                    Math.Pow(p.z, 2), 1 / 3f) > 15)
                {
                    stars.Add(p);
                    count++;
                }
            }
        }

The score is a number which increases over time and it grows faster everytime I pass a level. The level increases every 450 frames.

The last issue I had to address is the problem of asteroid collision. I make for the ship three positions (one for the ship and two for the wings) and every once in a while, I check the distance between all the asteroids and those three positions. If it is under a predefined value, I execute the collision event.

The project has six classes:

• AsteroidGenerator.cs - It handles the creation of asteroids in random places and with random sizes and speeds. It also has the method to query whether or not there has been a collision between the spaceship and an asteroid.
• Asteroid.cs - It handles all concerning an asteroid such as the movement, texture selection, drawing, among others.
• Star.cs - It has a method to create random white points and to draw them.
• Camera.cs - It handles the selection of the user camera and to set the right perspective view of the scene.
• SpaceShip.cs - This class contains all methods and attributes regarding the spaceship, such as movement, drawing, etc.
• Controller.cs - This class manages the game creation, game logic and contains all the classes needed to run the game. Here is a portion of code:

using System;
using System.Collections.Generic;
using System.Text;

namespace Naves
{
    public class Controller
    {
        Camera camara = new Camera();
        Star star = new Star();
        SpaceShip spaceShip = new SpaceShip();
        public SpaceShip Nave
        {
            get { return spaceShip; }set { spaceShip = value; }
        }
        public Camera Camara
        {
            get { return camara; }
        }
        public void BeginGame()
        {
            AsteroidGenerator.GenerateAsteroid(35, false);
        }
        public void ResetGame()
        {
            AsteroidGenerator.GenerateAsteroid(35, true);
            spaceShip.Reiniciar();
        }
        public void CreateObjects()
        {
            star.CreateStars(450);
            spaceShip.Create();
            Asteroid.Crear();
        }
        public void DrawScene()
        {
            star.Draw();
            AsteroidGenerator.DrawAsteroids();
            spaceShip.Dibujar();
        }
    }
}

Main.cs - This is the form which contains this visual components of the game. It contains the controller class and gives the player information through proper windows controls. It has a timer to periodically draw the scene and has the code for texture and object loading.

If you want to add sound to the project, uncomment the commented lines and press Ctrl+Alt+E and under managed debugging assistants, uncheck the loaderlock exception.

I am hoping to receive feedback from this example. If you like it, please vote or leave a comment below. I’ll try to make a version where the spaceship can shoot at the asteroids.

History

• 28^th December, 2011: Initial version