A New Version of My 3D Asteroid Game in OpenGL with C#

• Download source code - 2 MB

Introduction

This article is an update of my first article named “A Basic 3D Asteroid Game in OpenGL with C#”. In this version, I have added the shooting feature. I will try to explain it briefly here. In the first version of this updated article, the spaceship contained a mesh for the four rockets, I didn't know how to de-attach them in a 3D editor so I made the ship fire the four rockets at the same time. Then, the user The_inventor sent me the 3D file with each rocket in an individual mesh so I decided to rewrite this article in order to include those changes. Now each missile is fired individually.

The first thing to do is to get the meshes that contain the four rockets and place them on a list:

m = ContentManager.GetModelByName("nave.3DS");
m.CreateDisplayList();

missiles.Add(new Missile(new Vector3(),m.GetMeshWithName("Missle1")));
m.RemoveMeshByName("Missle1");

missiles.Add(new Missile(new Vector3(), m.GetMeshWithName("Missle2")));
m.RemoveMeshByName("Missle2");

missiles.Add(new Missile(new Vector3(), m.GetMeshWithName("Missle3")));
m.RemoveMeshByName("Missle3");

missiles.Add(new Missile(new Vector3(), m.GetMeshWithName("Missle4")));
m.RemoveMeshByName("Missle4");

After getting the mesh reference, we delete them from the model because we are going to draw and manage them in a different way than the ship.

//This is the function that draws a missile

        public void Draw()
        {
            if (fired == false)
                initialPos = shipPos; 

            Gl.glPushMatrix();
            if (fired)
            {
                initialPos.Z -= 0.1f;
                Gl.glTranslatef(initialPos.X, initialPos.Y, initialPos.Z);
                if (Math.Abs(initialPos.Z) > 35)
                {
                    fired = false;
                    initialPos = shipPos;
                }
            }
            else
            {
                Gl.glTranslatef(shipPos.X, shipPos.Y, shipPos.Z);
            }

            AsteroidGenerator.CheckCollisionMissile(initialPos, 0.5f);

            Gl.glScalef(0.3f, 0.3f, 0.3f);
            Gl.glDisable(Gl.GL_TEXTURE_2D);
            //Dont have a missile texture
            //Gl.glBindTexture
            //(Gl.GL_TEXTURE_2D, ContentManager.GetTextureByName("avion07.jpg"));
            missileMesh.Draw();
            Gl.glEnable(Gl.GL_TEXTURE_2D);  
            Gl.glPopMatrix();
        } 

After getting the missile, the missile may only have two statuses: when it is in the ship and when it is fired. If it is in the ship, I don’t have to do anything, just translate the missiles anytime I translate the ship.

I handle the missile asteroid collision in the following way. When a missile is shot, it checks if it is colliding with any asteroid. It does it the same way in which the ship checks collisions with the asteroids but it does another thing: if a collision is detected, the asteroid generator class which holds the asteroid list is told to delete that asteroid and to create an explosion. An explosion is a sphere object that anytime it is drawn, it expands its size, giving the idea of a shock wave, and then when a particular size is achieved, the object doesn’t draw anymore. Attention, this explosion wave follows some concepts of particle programming, which is live over time and a particular way to behave.

The project has eight classes, two added for this feature:

• ExplosionWave.cs: This is the class that handles the explosion, it’s a sphere object drawn by OpenGL quadrics.
• 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 everything 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 setting the right perspective view of the scene.
• SpaceShip.cs: This class contains all the 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 the code.
• Missile.cs: This class handles the drawing and logic of the missiles.

This game is only for educational purposes. I think the simpler the code, the beautiful it gets. Of course, there are a lot of things that you may improve like the diagonal moving suggestion made by the user Death259 that I included in this version. I also added points to the score when an asteroid is destroyed.

I am hoping to receive feedback from this example.

History

• 14^th May, 2014: Initial version