How to Make an Object Bounce in C#

Make a ball bounce in C#.

Making an object bounce in a Microsoft Visual C# application can be accomplished easily by using a few form properties and a timer control. C# is a programming language included in the Microsoft Visual Studio suite, and it can be used to create Windows Forms applications. Bouncing objects are often used in game applications, such as a ball bouncing inside a form. Use a timer control to keep track of the size of the form and reposition the ball accordingly.

Things You'll Need

• Microsoft Visual Studio installed

Instructions

1. Launch Microsoft Visual Studio. Click “New Project” on the left pane of the application window and expand “Other Languages” below “Installed Templates.” Click “Visual C#” and double-click “Windows Forms Application” from the center of the dialogue window to create a new project.

2. Double-click the form to create a new Form Load event. Insert the following code above “public Form1()” to create four integer global variables in this module:

   int dx;
   int dy;
   int x;
   int y;

3. Copy and paste the following code inside the “Form1_Load” event to generate a random number:

   Random rnd = new Random();
   dx = rnd.Next(1, 4);
   dy = rnd.Next(1, 4);
   x = rnd.Next(0, this.ClientSize.Width - 50 );
   y = rnd.Next(0, this.ClientSize.Height - 50);

4. Switch back to form design and right-click the form. Click “Properties” and click the "Events" icon, which resembles a lighting strike. Double-click next to “Paint” to create the event. Copy and paste the following code inside the event:

   e.Graphics.Clear(this.BackColor);
   e.Graphics.FillEllipse(Brushes.Black, x, y, 50, 50);
   e.Graphics.DrawEllipse(Pens.Black, x, y, 50, 50);

5. Switch back to form design and double-click “Timer” to add a new one to your project. Right-click the timer control and click “Properties.” Set “Enabled” to “True” and set “Interval” to “1.” Double-click the timer control to create a tick event. Add the following code to reposition the object:

   x += dx;
   if (x < 0)
   {
   dx = -dx;
   }
   else if (x + 50 > this.ClientSize.Width)
   {
   dx = -dx;
   }

   y += dy;
   if (y < 0)
   {
   dy = -dy;
   }
   else if (y + 50 > this.ClientSize.Height)
   {
   dy = -dy;
   }
   this.Invalidate();

6. Press “F5” to run the program and watch the ball bounce back and forth. Resize your form to bounce the ball faster or slower.

References

• Microsoft Developers Network: Visual C#
• YouTube: How to Make a Bouncing Ball in VB