Question

How do I set every non transparent pixel in an arbitrary Texture2D to let’s say Color.White temporarily?

Answer 1

Just a conditional loop? This won’t be exact syntax for it, but something among the lines of:

Texture2D texture = /*copy the texture you want to change*/;
Pixel pixel;/*note it's really inexact, so don't mind it, the idea is to show how it would be done*/
for(int i=0; i<texture.width; i++)
{
  for(int j=0; j<texture.height; j++)
  {
    pixel = texture.GetPixel(i, j);
    if(pixel.Color.A==1)
      pixel.Color = Color.White;
  }
}

I cannot stress this enough: do NOT just copy paste this in, this is similar to pseudocode, just there to show how it would be done.