I am working on a breakout game using c# and gdi+. I am unsure of how to implement the collision detection between the ball and the bricks. I am thinking about using a list function.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Timers;

namespace WindowsFormsApp1
{
    public partial class Form1 : Form
    {
        private static System.Timers.Timer aTimer;

        int xstep = 5;
        int ystep = 5;

        int x1 = 0;
        int y1 = 0;

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            this.DoubleBuffered = true;
            this.Paint += new PaintEventHandler (Form1_Paint);
            this.KeyDown += new KeyEventHandler(Form1_KeyDown);
            aTimer = new System.Timers.Timer(50);
            aTimer.Elapsed += new ElapsedEventHandler(timer1_Tick);
            aTimer.Start();
        }

        int move_paddle = 0;

        private void Form1_KeyDown(object sender, KeyEventArgs e)
        {
            switch (e.KeyCode)
            {
                case Keys.Left:
                    move_paddle-=5;
                    if(move_paddle <= -320)
                    {
                        move_paddle = -320;
                    }
                    break;
                case Keys.Right:
                    move_paddle+=5;
                    if(move_paddle >= 320)
                    {
                        move_paddle = 320;
                    }
                    break;
                default:
                    return;
            }
        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            e.Graphics.FillRectangle(Brushes.Black, 0, 0, 1104, 768);
            e.Graphics.DrawImage(Properties.Resources.paddle, new Rectangle(320+move_paddle, 425, 80, 40));
            this.Invalidate();
            for (int i = 0; i <= 480; i += 240) 
            {
            e.Graphics.DrawImage(Properties.Resources.red, new Rectangle(i, 0, 80, 40));
            }
            for (int i = 80; i <= 560; i += 240)
            {
            e.Graphics.DrawImage(Properties.Resources.green, new Rectangle(i, 0, 80, 40));
            }
            for (int i = 160; i <= 640; i += 240)
            {
            e.Graphics.DrawImage(Properties.Resources.blue, new Rectangle(i, 0, 80, 40));
            }

            for (int i = 0; i <= 480; i += 240)
            {
                e.Graphics.DrawImage(Properties.Resources.green, new Rectangle(i, 40, 80, 40));
            }
            for (int i = 80; i <= 560; i += 240)
            {
                e.Graphics.DrawImage(Properties.Resources.blue, new Rectangle(i, 40, 80, 40));
            }
            for (int i = 160; i <= 640; i += 240)
            {
                e.Graphics.DrawImage(Properties.Resources.red, new Rectangle(i, 40, 80, 40));
            }

            for (int i = 0; i <= 480; i += 240)
            {
                e.Graphics.DrawImage(Properties.Resources.blue, new Rectangle(i, 80, 80, 40));
            }
            for (int i = 80; i <= 560; i += 240)
            {
                e.Graphics.DrawImage(Properties.Resources.red, new Rectangle(i, 80, 80, 40));
            }
            for (int i = 160; i <= 640; i += 240)
            {
                e.Graphics.DrawImage(Properties.Resources.green, new Rectangle(i, 80, 80, 40));
            }
            e.Graphics.DrawImage(Properties.Resources.bullet, new Rectangle(355 + x1, 232 + y1, 10, 10));
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            if (x1 >= 360 || x1 <= -360) 
            {
                xstep = -xstep;
            }
            if (y1 >= 227 || y1 <= -232)
            {
                ystep = -ystep;
            }
            x1 += xstep;
            y1 += ystep;
        }
    }
}

I have stubbed out my list function in c#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ListBricks
{
    class Program
    {
        class Brick
        {
            public int x;
            public int y;
        }
        static void Main(string[] args)
        {
            List<Brick> bricks = new List<Brick>();
            int count = 0;
            for (int j = 0; j <= 80; j += 40)
            {
                for (int i = 0; i <= 480; i += 240)
                {
                    bricks.Add(new Brick());
                    bricks[count].x = i;
                    bricks[count].y = j;
                    count++;
                }
                for (int i = 80; i <= 560; i += 240)
                {
                    bricks.Add(new Brick());
                    bricks[count].x = i;
                    bricks[count].y = j;
                    count++;
                }
                for (int i = 160; i <= 640; i += 240)
                {
                    bricks.Add(new Brick());
                    bricks[count].x = i;
                    bricks[count].y = j;
                    count++;
                }
            }
            foreach (Brick aBrick in bricks)
            {
                Console.WriteLine(aBrick.x);
                Console.WriteLine(aBrick.y);
            }
        }
    }
}

I have added the list function into my code.

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            e.Graphics.FillRectangle(Brushes.Black, 0, 0, 1104, 768);
            e.Graphics.DrawImage(Properties.Resources.paddle, new Rectangle(320+move_paddle, 425, 80, 40));
            this.Invalidate();
            List<Brick> bricks = new List<Brick>();
            int count = 0;

            for (int j = 0; j <= 80; j += 40)
            {
                for (int i = 0; i <= 480; i += 240)
                {
                    bricks.Add(new Brick());
                    bricks[count].x = i;
                    bricks[count].y = j;
                    e.Graphics.DrawImage(Properties.Resources.red, new Rectangle(bricks[count].x, bricks[count].y, 80, 40));
                    count++;
                }
                for (int i = 80; i <= 560; i += 240)
                {
                    bricks.Add(new Brick());
                    bricks[count].x = i;
                    bricks[count].y = j;
                    e.Graphics.DrawImage(Properties.Resources.green, new Rectangle(bricks[count].x, bricks[count].y, 80, 40));
                    count++;
                }
                for (int i = 160; i <= 640; i += 240)
                {
                    bricks.Add(new Brick());
                    bricks[count].x = i;
                    bricks[count].y = j;
                    e.Graphics.DrawImage(Properties.Resources.blue, new Rectangle(bricks[count].x, bricks[count].y, 80, 40));
                    count++;
                }
            }
                    e.Graphics.DrawImage(Properties.Resources.bullet, new Rectangle(355 + x1, 232 + y1, 10, 10));
        }

pbivens67 said:
I am unsure of how to implement the collision detection between the ball and the bricks.

Because Breakout balls can become very fast usually, it's likely necessary to process multiple collisions in one frame, and calculating the path of the ball. So you calculate the distance the ball should travel (timestep * ball velocity), and then trace a ray through the grid of bricks, which may look lime this:

We get 4 segments, and after the sum of all segments equals the calculated length we are done.

So that's a bit of geometry and surely the hardest part of the game. You can limit ball speed to ensure you have to process only one brick per frame, but that's not much easier because you have to work out ball-box collision response anyway.

Eventually it is easier to treat the problem like this:

By extending the rectangle with the ball shape (Minkovski Sum of ball and brick), we can treat the ball only as a point, while the rectangles become rounded.

The safe version is to not move the ball the full delta, but pixel per pixel. At every step you check for a collision (Yes, computers nowadays are easily fast enough for doing that) and handle it. Handling a collision may reset/reverse the left delta for the current frame, be aware of that.

To speed things up you could also just put those bricks into a special collision array, that are reachable for the ball. So every brick which is on the bottom of it's column and bricks that don't have any left/right neighbour. Some spatial positioning data structure would also help to speed things up but it should be ok for C# to perform some checks per frame.

Instead of creating new rectangles every frame, you should precompute them once and store them in an array. Then you just need to perform a rectangle collision check with the rectangle of your ball. Rectangle.IntersectsWith is a usefull neat function which will tell if the rectangles overlap each other before you start to compute the bounce angle

well I have implemented a collision between the ball and the paddle, is there a way to implement the collision between the ball and the bricks that is streamlined?

here is my collision code so far.

            if(paddle.IntersectsWith(ball))
            {
                paddle.Intersect(ball);
                if(!paddle.IsEmpty)
                {
                    ystep = -ystep;
                }
            }

pbivens67 said:
if(!paddle.IsEmpty)

Never name a bool with a negative connotation.

fleabay said:
Never name a bool with a negative connotation

In C#, a lot an I mean A LOT of classes have such members and I don't see any reason why this shouldn't be valid

Shaarigan said:
I don't see any reason why this shouldn't be valid

It's valid, just confusing and hard to reason about especially when you have several bools strung together.

What do you mean, in C# a lot of classes have such members? You mean like a standard library?