pointers

[Storm Trooper]

how do pointers help to give a turbo charge to rendering?
and how do you use them?
say for example, a usual FOR X and Y LOOP.

thanks again,
tR4nt0r

[hellfire]

let's assume you want to fill an image which is simply an array of width*height integers.

instead of adressing each pixel individually, like this:

Code Select Expand


for (y=0; y < height; y++)
{
  for (x=0; x < width; x++)
  {
    adress= y * width + x;
    image[adress] = color;
  }
}


...you just increase your pointer when stepping from one pixel to the next:

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dest= image;
for (y=0; y < height; y++)
{
  for (x=0; x < width; x++)
  {
    *dest= color;
    dest++;
  }
}


any half-decent compiler will do this optimization automatically for you, though.