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Example

If you somehow don’t understand input, here’s a little example to clench the deal:

#include "gba.h"          //Defined in Volume 2 (ALWAYS include this first)
#include "keypad.h"
#include "screenmodes.h"  //Defined in Volume 2
 
u16* theVideoBuffer = (u16*)VideoBuffer;
#define RGB(r,g,b) (r+(g<<5)+(b<<10))   //Macro to build a color
 
void FillScreen( u16 color )
{
  u16 x, y;
  for ( x = 0; x < 240; x++ )
    for ( y = 0; y < 160; y++ )
      theVideoBuffer[ y * 240 + x ] = color;
}
 
int main()
{
  SetMode( SCREENMODE3 | BG2ENABLE );
 
  while ( 1 )
    if ( KEY_DOWN( KEYUP) )
      FillScreen( RGB(31,0,0) );
    else if ( KEY_DOWN( KEYDOWN) )
      FillScreen( RGB(0,31,0) );
    else if ( KEY_DOWN(KEYLEFT) )
      FillScreen( RGB(0,0,31) );
    else if ( KEY_DOWN(KEYRIGHT) )
      FillScreen( RGB(31,31,0) );
    else if ( KEY_DOWN(KEYA) )
      FillScreen( RGB(0,31,31) );
    else if ( KEY_DOWN(KEYB) )
      FillScreen( RGB(31,0,31) );
    else if ( KEY_DOWN(KEYSTART) )
      break;
 
  return 0;
}

All the demo does is fill the screen with a certain color depending on what button is pressed. Start ends the program.

Next Article

In the next article, I’m going to give you information on a slightly complex/tricky topic-tile modes.

Acknowledgements

I would like to thank dovoto, as his tutorials have been my biggest source of information on GBA development since I started.  Check out his site at www.thepernproject.com.  I'd also like to thank the guys in #gamedev and #gbadev on EFNet in IRC for all their help, and all the help they'll be giving me as I write these articles. Furthermore, I would like to thank www.gbadev.org/.  The site is a great resource, and it is definitely worth your time.

Special thanks to www.gamedev.net for being my largest game development resource and for putting my articles on their site.  Extra special thanks to Inspi for helping me with my coding woes and checking over this article.

If you have any questions or comments, you can always e-mail me at genesisgenocide@yahoo.com or nairb@usa.com. I can't promise I'll answer your questions, like your comments, or listen to your suggestions, but I'll at least read the e-mail (as long as it doesn't look like spam).