Thread: Software blitter

So I should do some pre-processing when I load my sprites?

Code:

struct drawPart{
  byte startPixel;
  int size;
}

while(not at end of sprite)
   if(currentPixel.alpha != 0)
       increase drawPart.size;
   else
       create new drawPart;

And then when drawing it I just draw all the drawParts that is created by the pre-processing?
Thanks for the input so far

EDIT:
Clipping would break the data that is created when loading the sprite I think. The only way to get it to work this way is to create a list of drawParts each time I want to draw the sprite? I think that would be slower then what I have so far.

Sort of, but remember you have to toggle between read/write states. I'm writing this off the top of my head so the pseudocode may still have errors in it, but something like:

Code:

Uint32 skip_write[10000];

Precalc(image im)
    int size = im.x * im.y;
    bool state = 0;
    int index = 0;
    int count = 0;
    for(int i=0; i<size; i++)
        if(state)
            if(im.pixel[i] == MASK)
                  count++;
            else
                  skip_write[index] = count;
                  count = 1;
                  index++;
                  state = false;
        else
           if(im.pixel[i] != MASK)
                  count++;
           else
                  skip_write[index] = count;
                  count =1;
                  index++;
                  state = true;

Edit: you also need to note if the first pixel is masked or not, also using a linked list for this can save a lot of memory.