Silverlight 3 Writeable Bitmap API - Plasma

Crossposted on lab101.be

Inspired by old school MS DOS demos and this Flash Alchemy experiment.
Found out that someone already ported some code from the Alchemy experiment to C#.
So after some tweaking and some help of my colleague Frederik it’s up and running in Silverlight 3 beta.

I’m using two threads to speed up the plasma calculation when moving the dots, since everybody has a duo,triple,quad,octa … core CPU these days,
One thread does even lines and the other odd lines (interlacing).

public static void GeneratePlasmaEvenLines() { int index = 0;


       for (var x = 0; x < width; x +=2)

       {

         for (var y = 0; y < height ; y+=1)

         {

           uint color = CalculatePixel(x, y);

           plasma[index++] = color % 255;

         }

         index += width;

       }

     }
     public static void GeneratePlasmaOddLines()

     {

         int index = width;

         for (var x = 1; x < width; x+=2)

         {

             for (var y = 0; y < height; y+=1)

             {

                 uint color = CalculatePixel(x, y);

                 plasma[index++] = color % 255;

             }

             index += height;

         }

     }
  private static uint CalculatePixel(int x, int y)

     {

         int w = (int) param6;

         int h = (int)param5;

         uint color = (uint)

        (

              128.0 + (param3 * Math.Sin(x / param1))

            + 128.0 + (param4 * Math.Sin(y / param2))

            + 128.0 + ((param5/4) * Math.Sin(Math.Sqrt((double)((x - w)* (x - w) + (y - h ) * (y - h))) / 9.0))

            + 128.0 + ((param6/4)* Math.Sin(Math.Sqrt((double)(x * x + y * y)) / 9.0))

        ) / 4;
         // Add shift position to sync the color

         color +=  LastShift;

         return color;

     }

Placing the pixels on the canvas with the brand new bitmap API.

private void BuildBitmap(uint[] data) { writeableBitmap.Lock(); uint colorValue=0;


            for (int x = 0; x < imageWidth; x++)

            {

                for (int y = 0; y < imageHeight; y++)

                {

                    // set the pixel value

                    int palletIndex = (int)data[y * imageWidth + x];

                    colorValue = GeneratePlasma.palette[palletIndex];
                    writeableBitmap[y * imageWidth + x] = (int) colorValue;

                }

            }
            writeableBitmap.Invalidate();

            writeableBitmap.Unlock();
            btImage.Source = writeableBitmap;

            GC.Collect();

        }