Question

I really need help. I am making a game app for my final year project. It is a simple game where you have to shoot a ball into a target by rebounding of walls or angled blocks. However i need help in 2 areas:

1. the shooting mechanism is similar to that of stupid zombies. There is a crosshairs where you touch on the screen to indicate which direction you want the ball to be shot at. On release the ball should move into that direction and hopefully gets into the target and if not gravity and friction causes it to come to a stop.

   The problem is how do I code something like this?

2. I need the ball to rebound of the walls and I will have some blocks angled so that the ball has to hit a certain part to get to the target. The ball will eventually come to a stop if the target is not reached.

   How can I make a method to create the collisions of the wall and blocks?

I have spent the last weeks trying to find tutorials to help me make the game but have not found much specific to the type of game I am making. It would be great if sample code or template could be provided as this is my first android app and it is for my final year project and i do not have much time left.

Thank you in advance
akkki

Answer 1

Your question is too generic for stack overflow no one is going to do your project for you. Assuming you have basic programming experience if not get books and learn that first.

Assuming you already chose Android because of your tag, and assuming 2d game as it is easier.

Pre requests:
Install java+eclipse+android sdk if you havent already.
Create a new project and use the lunar landar example, make sure it runs on your phone or emulator.

Starting sample:
The lunar landar has a game loop a seperate thread which constantly redraws the whole screen, it does this by constantly calling the doDraw function. You are then supposed to use the canvas to draw lines, circles, boxes, colours and bitmaps to resemble your game. (canvas.draw….) Lunar landar does not use openGL so its slower but much easier to use.

Stripping the sample:
You probably don’t want keyevents or the lunar spaceship!
Delete everything in the onDraw function
Delete the onKeyUp, onKeyDown
Delete any errors what happen
Create a new

@Override
public boolean onTouchEvent(MotionEvent event){
    return false;
}

Run it you should get a blank screen, this is your canvas to start making your game… You mentioned balls, break it down to what a ball is: A position and direction, create variables for the balls x,y direction_x and direction_y the touch event will want to change the balls direction, the draw event will want to move the ball (adding the direction x,y to the ball x,y) and draw the ball (canvas.drawCircle(x,y,radius,new Paint())) want more balls search and read about arrays. Most importantly start simple and experiment.

2 collisions

Collisions can be done in the dodraw function and broken down to: moving an object, checking if that object has passed where it is supposed to go and if so move it back before anyone notices…. There are many differently techniques of collision detection:

• If your walls are all horizontal and vertical (easiest) then box collisions checks the balls new x,y+-radius against a walls x,y,width and height its one big if statement and google has billions of examples.

• If your walls are angled then your need line collision detection, you basically have a line (vector) of where your ball is heading a vector of your wall create a function to check where two lines collide and check if that point is both on the wall and within the radius of your ball (google line intersection functions)

• or you can use colour picking, you draw the scene knowing all your walls are red for example, then check if the dot where the new ball x,y is, is red and know you hit

Good luck, hope this helped a little, keep it simple and trial and error hopefully this gets you started and your next questions can be more specific.