Thread: drawing minimaps and radar screens.

Hi!

Perhaps I missunderstood your question, which will make this answer look kinda redicolous, but anyway:

I figured you are trying to do something similar to the radar used in Counter-Strike.

To achieve this I would make a bitmap in grayscale, which defines the form of the radar, render this, using blending, to the stencil buffer, in order to mask out the rest of the screen.

Then place the camera high above the map, and render the "players" as dot's on the radar.

Guess this could work for you.

/Laos

trade RAM for speed. Don't calculate on the fly, just load a smaller, 2D, grayscale version of your level (top-down), and the clip a rectangle the size of your radar out of it. Whereever player's point of view (POV) moves, grab the correspondingly scaled/positioned chunk off the radar pixmap and display it in the 48x48 radar display block.

If you are programming fo 32-bit and using a compiler that supports MMX in inline asm or an assembler that does you could do this very fast.

I cannot see how that small of a rectangular bitmap on the screen could slow things down that much, even if you did use a transparent effect on it. This is a simple linear interpolation between the pixel that is there and the pixel you want to put there. Using linear interpolation you could get more of the background image if you preferred, or you could get more of the foreground or the super-imposed image.

Code:

short LI(short v1,short v2,double f1)
{
  short final=0;
  //LI=v1+f1*(v2-v1);
  asm {
    fild [v2]               //integer load v2 to st(0)
    fisub [v1]            //integer subtract v1 from st(0)
    fmul [f1]             //float multiply f1 * st(0)
    fiadd [v1]           //integer add v1 to st(0)
    fistp [final]         //integer store in final,pop st(0)
  }
  return final;
}