Click here to Skip to main content
15,895,142 members
Articles / Programming Languages / C#

A C# water effect picture control

Rate me:
Please Sign up or sign in to vote.
4.83/5 (24 votes)
29 Aug 2002 192.4K   6.4K   79  
A C# implementation of the popular water surface effect.
using System;
using System.Collections;
using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace WaterEffectDemo
{
	/// <summary>
	/// 
	/// </summary>
	public class WaterEffectControl : System.Windows.Forms.Panel
	{
		private System.Windows.Forms.Timer effectTimer;
		private System.ComponentModel.IContainer components;

		private Bitmap		_bmp;
		private short[,,]	_waves;
		private int			_waveWidth;
		private int			_waveHeight;
		private int			_activeBuffer = 0;
		private bool		_weHaveWaves;
		private int			_bmpHeight,_bmpWidth;
		private byte[]		_bmpBytes;		
		private BitmapData	_bmpBitmapData;		
		private int			_scale;
	

		private void InitializeComponent()
		{
			this.components = new System.ComponentModel.Container();
			this.effectTimer = new System.Windows.Forms.Timer(this.components);
			// 
			// effectTimer
			// 
			this.effectTimer.Tick += new System.EventHandler(this.effectTimer_Tick);
			// 
			// WaterEffectControl
			// 
			this.Paint += new System.Windows.Forms.PaintEventHandler(this.WaterEffectControl_Paint);
			this.MouseMove += new System.Windows.Forms.MouseEventHandler(this.WaterEffectControl_MouseMove);

		}
	
		public WaterEffectControl()
		{
			InitializeComponent();
			effectTimer.Enabled = true;
			effectTimer.Interval = 50;
			SetStyle(ControlStyles.UserPaint, true);
			SetStyle(ControlStyles.AllPaintingInWmPaint, true);
			SetStyle(ControlStyles.DoubleBuffer, true);
			this.BackColor = Color.White;
			_weHaveWaves = false;			
			_scale = 1;
			
		}

		public WaterEffectControl(Bitmap bmp) : this()
		{
			this.ImageBitmap = bmp;			
		}

		protected override void Dispose( bool disposing )
		{
			_bmp.UnlockBits(_bmpBitmapData);
			if( disposing )
			{
				if (components != null) 
				{
					components.Dispose();
				}
			}
			base.Dispose( disposing );
		}

		/// <summary>
		/// Timer handler
		/// </summary>
		/// <param name="sender"></param>
		/// <param name="e"></param>
		private void effectTimer_Tick(object sender, System.EventArgs e)
		{	

			if(_weHaveWaves)
			{
				Invalidate();

				ProcessWaves();

			}
		}

		/// <summary>
		/// Paint handler
		/// 
		/// Calculates the final effect-image out of
		/// </summary>
		/// <param name="sender"></param>
		/// <param name="e"></param>
		public void WaterEffectControl_Paint(object sender, System.Windows.Forms.PaintEventArgs e)
		{
	
			using(Bitmap tmp = (Bitmap)_bmp.Clone())
			{
				
				int xOffset, yOffset;
				byte alpha;
			
				if(_weHaveWaves)
				{
					BitmapData tmpData =  tmp.LockBits(new Rectangle(0,0,_bmpWidth,_bmpHeight), ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
					
					byte[] tmpBytes = new Byte[_bmpWidth*_bmpHeight*4];

					Marshal.Copy(tmpData.Scan0,tmpBytes,0,_bmpWidth*_bmpHeight*4);
					
					for(int x=1; x<_bmpWidth -1; x++)
					{
						for(int y=1; y<_bmpHeight -1; y++)
						{
							int waveX = (int)x >> _scale;
							int waveY = (int)y >> _scale;

							//check bounds
							if(waveX <= 0) waveX = 1;
							if(waveY <= 0) waveY = 1;
							if(waveX >= _waveWidth-1) waveX = _waveWidth-2;
							if(waveY >= _waveHeight-1) waveY = _waveHeight-2;

							//this gives us the effect of water breaking the light
							xOffset = (_waves[waveX-1,waveY,_activeBuffer] -_waves[waveX+1,waveY,_activeBuffer]) >> 3;
							yOffset = (_waves[waveX,waveY-1,_activeBuffer] -_waves[waveX,waveY+1,_activeBuffer]) >> 3;

							if((xOffset != 0) || (yOffset != 0))
							{
								//check bounds
								if(x+xOffset >= _bmpWidth-1)	xOffset = _bmpWidth - x - 1;
								if(y+yOffset >= _bmpHeight-1)	yOffset = _bmpHeight - y - 1;
								if(x+xOffset < 0)	xOffset = -x;
								if(y+yOffset < 0)	yOffset = -y;
								
								//generate alpha
								alpha = (byte)(200-xOffset);
								if(alpha < 0) alpha = 0;
								if(alpha > 255) alpha = 254;

								//set colors
								tmpBytes[4*(x + y*_bmpWidth)]		= _bmpBytes[4*(x+xOffset + (y+yOffset)*_bmpWidth)];
								tmpBytes[4*(x + y*_bmpWidth) + 1]	= _bmpBytes[4*(x+xOffset + (y+yOffset)*_bmpWidth) + 1];
								tmpBytes[4*(x + y*_bmpWidth) + 2]	= _bmpBytes[4*(x+xOffset + (y+yOffset)*_bmpWidth) + 2];
								tmpBytes[4*(x + y*_bmpWidth) + 3]	= alpha;
								
							}

						}
					}

					//copy data back
					Marshal.Copy(tmpBytes, 0, tmpData.Scan0, _bmpWidth*_bmpHeight*4);
					tmp.UnlockBits(tmpData);
					
				}

				e.Graphics.DrawImage(tmp,0,0,this.ClientRectangle.Width, this.ClientRectangle.Height);
				
			}
			
		}

		/// <summary>
		/// This is the method that actually does move the waves around and simulates the
		/// behaviour of water.
		/// </summary>
		private void ProcessWaves()
		{
			int newBuffer = (_activeBuffer == 0) ? 1 : 0;
			bool wavesFound = false;

			for(int x=1; x<_waveWidth -1; x++)
			{
				for(int y=1; y<_waveHeight -1; y++)
				{
					_waves[x,y,newBuffer] = (short)(
											((_waves[x-1,y-1,_activeBuffer] +
											_waves[x,y-1,_activeBuffer] +
											_waves[x+1,y-1,_activeBuffer] +
											_waves[x-1,y,_activeBuffer] +
											_waves[x+1,y,_activeBuffer] +
											_waves[x-1,y+1,_activeBuffer] +
											_waves[x,y+1,_activeBuffer] +
											_waves[x+1,y+1,_activeBuffer]) >> 2) - _waves[x,y,newBuffer]);
					
					//damping
					if(_waves[x,y,newBuffer] != 0)
					{
						_waves[x,y,newBuffer] -= (short)(_waves[x,y,newBuffer] >> 4);					
						wavesFound = true;
					}
					
					
				}
			}

			_weHaveWaves = wavesFound;
			_activeBuffer = newBuffer;

		}


		/// <summary>
		/// This function is used to start a wave by simulating a round drop
		/// </summary>
		/// <param name="x">x position of the drop</param>
		/// <param name="y">y position of the drop</param>
		/// <param name="height">Height position of the drop</param>
		private void PutDrop(int x, int y, short height)
		{
			_weHaveWaves = true;
			int radius = 20;
			double dist;

			for(int i = -radius; i<=radius; i++)
			{
				for(int j = -radius; j<=radius; j++)
				{
					if(((x+i>=0) && (x+i<_waveWidth-1)) && ((y+j>=0) && (y+j<_waveHeight-1)))
					{
						dist = Math.Sqrt(i*i +j*j);
						if(dist<radius)
							_waves[x+i,y+j,_activeBuffer] = (short)(Math.Cos(dist*Math.PI  / radius) * height);
					}
				}
			}
		}

		/// <summary>
		/// The MouseMove handler.
		/// </summary>
		/// <param name="sender"></param>
		/// <param name="e"></param>
		private void WaterEffectControl_MouseMove(object sender, System.Windows.Forms.MouseEventArgs e)
		{
			if(e.Button == MouseButtons.Left)
			{
				int realX = (int)((e.X / (double)this.ClientRectangle.Width)*_waveWidth);
				int realY = (int)((e.Y / (double)this.ClientRectangle.Height)*_waveHeight);
				PutDrop(realX,realY,200);
			}
		}


		#region Properties
		/// <summary>
		/// Our background image
		/// </summary>
		public Bitmap ImageBitmap
		{
			get { return _bmp; }
			set 
			{
				_bmp = value;
				_bmpHeight = _bmp.Height;
				_bmpWidth = _bmp.Width;

				_waveWidth = _bmpWidth >> _scale;
				_waveHeight = _bmpHeight  >> _scale;
				_waves = new Int16[_waveWidth,_waveHeight, 2];								

				_bmpBytes = new Byte[_bmpWidth*_bmpHeight*4];
				_bmpBitmapData =  _bmp.LockBits(new Rectangle(0,0,_bmpWidth,_bmpHeight), ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb);
				Marshal.Copy(_bmpBitmapData.Scan0,_bmpBytes,0,_bmpWidth*_bmpHeight*4);
			}
		}

		/// <summary>
		/// The scale of the wave matrix compared to the size of the image.
		/// Use it for large images to reduce processor load.
		/// 
		/// 0 : wave resolution is the same than image resolution
		/// 1 : wave resolution is half the image resolution
		/// ...and so on
		/// </summary>
		public int Scale
		{
			get { return _scale; }
			set { _scale = value;	}
		}
		#endregion
	}
}

By viewing downloads associated with this article you agree to the Terms of Service and the article's licence.

If a file you wish to view isn't highlighted, and is a text file (not binary), please let us know and we'll add colourisation support for it.

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here


Written By
Web Developer
Germany Germany
If you are not living on the edge you are wasting space Wink | ;)

Comments and Discussions