GDI+ Examples: Collision Detection I

	GDI+ Examples: Collision Detection I

Introduction

Objects are said to collide when they touch each other. This is something very important in graphical applications and games, etc. It used to be particularly difficult but nowadays, it mostly depends on how you want to implement. In this exercise, we will draw to circles that keep moving on a form. If the meet (collide), they stop.

This example uses shapes of the Microsoft Visual Basic Power Packs.

Application: Introducing the Tree View Control

Start Microsoft Visual Studio or Microsoft Visual C# Express
To create an application, on the main menu, click File -> New Project...
Set the project type to Empty Project
Change the name to CollisionDetection1
Click OK
On the main menu, click Project -> CollisionDetection1 Properties...
In the Output Type combo box, select Windows Application
On the main menu, click Project -> Add Reference...
Click the .NET tab
In the list, click System
Press and hold Ctrl
Click System.Drawing
Click System.Windows.Forms
Click Microsoft.VisualBasic.PowerPacks.Vs
Click OK
On the main menu, click Project -> Add New Item...
Click Code File
Change the name to CollisionDetection
Click Add

In the empt document, type the following:

using System;
using System.Drawing;
using System.Windows.Forms;

public class CollisionDetection : Form
{
    static int xGreen;
    static int xBrown;

    static int yGreen;
    static int yBrown;

    static bool IsMovingDownGreen;
    static bool IsMovingDownBrown;

    static bool IsMovingRightGreen;
    static bool IsMovingRightBrown;

    Timer tmrMover;
    Microsoft.VisualBasic.PowerPacks.OvalShape osGreen;
    Microsoft.VisualBasic.PowerPacks.OvalShape osBrown;
    Microsoft.VisualBasic.PowerPacks.ShapeContainer shpContainer;

    public CollisionDetection()
    {
        InitializeComponent();
    }

    private void InitializeComponent()
    {
        xGreen = 0;
        xBrown = 250;

        yGreen = 0;
        yBrown = 500;

        IsMovingDownGreen = false;
        IsMovingDownBrown = false;

        IsMovingRightGreen = false;
        IsMovingRightBrown = false;

        tmrMover = new Timer();
        tmrMover.Interval = 2;
        tmrMover.Enabled = true;
        tmrMover.Tick += new EventHandler(tmrMoverTicked);

        osBrown = new Microsoft.VisualBasic.PowerPacks.OvalShape();
        osBrown.BackColor = Color.FromArgb(255, 128, 0);
        osBrown.BackStyle = Microsoft.VisualBasic.PowerPacks.BackStyle.Opaque;
        osBrown.BorderColor = Color.FromArgb(128, 64, 0);
        osBrown.BorderWidth = 2;
        osBrown.Size = new System.Drawing.Size(80, 80);

        osGreen = new Microsoft.VisualBasic.PowerPacks.OvalShape();
        osGreen.BackColor = Color.FromArgb(192, 255, 192);
        osGreen.BackStyle = Microsoft.VisualBasic.PowerPacks.BackStyle.Opaque;
        osGreen.BorderColor = Color.Cyan;
        osGreen.BorderWidth = 2;
        osGreen.Location = new Point(100, 100);
        osGreen.Size = new Size(80, 80);

        shpContainer = new Microsoft.VisualBasic.PowerPacks.ShapeContainer();
        shpContainer.Location = new System.Drawing.Point(0, 0);
        shpContainer.Margin = new System.Windows.Forms.Padding(0);
        shpContainer.Shapes.Add(osBrown);
        shpContainer.Shapes.Add(osGreen);
        shpContainer.Size = new System.Drawing.Size(778, 576);
        
        BackColor = System.Drawing.Color.Black;
        ClientSize = new System.Drawing.Size(778, 576);
        Controls.Add(shpContainer);
        StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;

        SetStyle(ControlStyles.UserPaint, true);
        SetStyle(ControlStyles.AllPaintingInWmPaint, true);
        SetStyle(ControlStyles.DoubleBuffer, true);
    }

    private void tmrMoverTicked(object sender, EventArgs e)
    {
        // If the status of the origin indicates that it is moving right,
        // then increase the horizontal axis
        if (IsMovingRightGreen == true)
            xGreen++;
        else // If it's moving left, then decrease the horizontal movement
            xGreen--;

        // If the status of the origin indicates that it is moving down,
        // then increase the vertical axis
        if (IsMovingDownGreen == true)
            yGreen++;
        else // Otherwise, decrease it
            yGreen--;

        // Collision: if the axis hits the right side of the screen,
        // then set the horizontal moving status to "Right", which will be used
        // by the above code
        if ((xGreen + osGreen.Width) >= ClientSize.Width)
            IsMovingRightGreen = false;
        if ((xGreen + osGreen.Width) <= 40)
            IsMovingRightGreen = true; ;

        if ((yGreen + osGreen.Height) > ClientSize.Height)
            IsMovingDownGreen = false;
        if ((yGreen + osGreen.Height) <= 40)
            IsMovingDownGreen = true;

        BackColor = Color.Black;

        osGreen.Location = new Point(xGreen, yGreen);

        // -----------------------------------------------------------

        if (IsMovingRightBrown == true)
            xBrown++;
        else // If it's moving left, then decrease the horizontal movement
            xBrown--;

        // If the status of the origin indicates that it is moving down,
        // then increase the vertical axis
        if (IsMovingDownBrown == true)
            yBrown++;
        else // Otherwise, decrease it
            yBrown--;

        // Collision: if the axis hits the right side of the screen,
        // then set the horizontal moving status to "Right", which will be used
        // by the above code
        if ((xBrown + osBrown.Width) >= ClientSize.Width)
            IsMovingRightBrown = false;
        if ((xBrown + osBrown.Width) <= 40)
            IsMovingRightBrown = true; ;

        if ((yBrown + osBrown.Height) > ClientSize.Height)
            IsMovingDownBrown = false;
        if ((yBrown + osBrown.Height) <= 40)
            IsMovingDownBrown = true;
        osBrown.Location = new Point(xBrown, yBrown);

        if (osBrown.Bounds.IntersectsWith(osGreen.Bounds))
        {
            tmrMover.Enabled = false;
            /*
             * Random rndNumber = new Random();
            
               xGreen = rndNumber.Next(Width);
               xBrown = rndNumber.Next(Width);

               yGreen = rndNumber.Next(Height);
               yBrown = rndNumber.Next(Height);
            */
        }
    }
}

public class Exercise
{
    public static int Main()
    {
        Application.Run(new CollisionDetection());
        return 0;
    }
}

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