Codelab Snippets Thread

[Illnab1024]

I figure we need a place to put all of our small tidbits of code we use to simplify tasks.

Here are some of my codelab scripts:

Red channel:

void Render(Surface dst, Surface src, Rectangle rect)
{
   for(int y = rect.Top; y < rect.Bottom; y++)
   {
       for (int x = rect.Left; x < rect.Right; x++)
       {
           ColorBgra color = src[x, y];
           color.B = 0;
           color.G = 0;
           dst[x, y] = color;
       }
   }
}

Blue channel:

void Render(Surface dst, Surface src, Rectangle rect)
{
   for(int y = rect.Top; y < rect.Bottom; y++)
   {
       for (int x = rect.Left; x < rect.Right; x++)
       {
           ColorBgra color = src[x, y];
           color.R = 0;
           color.G = 0;
           dst[x, y] = color;
       }
   }
}

Green channel:

void Render(Surface dst, Surface src, Rectangle rect)
{
   for(int y = rect.Top; y < rect.Bottom; y++)
   {
       for (int x = rect.Left; x < rect.Right; x++)
       {
           ColorBgra color = src[x, y];
           color.B = 0;
           color.R = 0;
           dst[x, y] = color;
       }
   }
}

Invert alpha channel:

void Render(Surface dst, Surface src, Rectangle rect)
{
   for(int y = rect.Top; y < rect.Bottom; y++)
   {
       for (int x = rect.Left; x < rect.Right; x++)
       {
           ColorBgra color = src[x, y];
           color.A = (byte)(255-color.A);
           dst[x, y] = color;
       }
   }
}

Pixel value to alpha:

void Render(Surface dst, Surface src, Rectangle rect)
{
   for(int y = rect.Top; y < rect.Bottom; y++)
   {

       for (int x = rect.Left; x < rect.Right; x++)
       {
           byte full = (byte)(255);
           ColorBgra c = src[x, y];
           int luma = (int)(c.R*0.3 + c.G*0.59+ c.B*0.11);
           c.A = (byte)(255-luma);
           dst[x, y] = c; 
       }
   }
}

I have several others..

You are encouraged to post your scripts and constructively criticize others' scripts.

P.S. put the channels in three layers (R, B, and G), stting each layer's mode to additive if you want to edit in channels...

Sources EDITED for less stupidity...

[Rick Brewster]

I must ask why you are declaring the "color" variable outside of the Render function ... that instantly makes it not thread safe. Just put it inside the Render function and you're good.

[Illnab1024]

It didn't build right when I put it inside the function...I dunno why.

I am very much a novice to C#

EDIT: Now I see...you must define the variable, not just initialize it, for it to withhold in a function.

[Rick Brewster]

Yes, that looks much better now

[BoltBait]

Is there a way in codelab to manipulate the HSV values of a pixel? Or, do you always have to use RGB?

[Rick Brewster]

Pixels do not contain HSV values. They are always stored as BGRA. You must convert to HSV, do manipulation in that form, and then convert back to BGRA.