// Simple infinite 360degree scroller using either digital or analogue pad.

// Press Left/Right/up/down to speedup/slowdown change direction etc.
// Just an experimental demo made available to illustrate the technique.

// by James Shaughnessy james@manc.u-net.com
// http://www.netyaroze-europe.com/~shaughnj


#define MAXSPEED 24                     // Max scroll speed pixels/frame
#define NULLZONE 32                     // PAD centre nullzone radius
                                        // Acts as PAD sensitivity --
                                        // Lower number = higher sensitivity

#include <stdio.h>
#include <libps.h>

#include "pad.h"


// Global Variables
u_long padStatus = 0;
short offsetx = 0, offsety = 0;         // Offset level
short incx = 0, incy = 0;               // Scroll increment pixel/frame

u_char PAD1lh, PAD1lv, PAD1rh, PAD1rv;  // Analog PAD values


extern DISPENV GsDISPENV;


// Function Declarations
void DrawPicture();
void SetScrollSpeed();

main()
{
  RECT tleft, tright;
  RECT bleft, bright;

  // Setup graphics PAL
  SetVideoMode(MODE_PAL);
  GsInitGraph(320, 256, 4, 0, 0);
  GsDISPENV.screen.y = 20;
  GsDISPENV.screen.h = 256;

  GsDefDispBuff(0, 0, 0, 0);

  PadInit();

  DrawPicture();


  while(1)
  {
    padStatus = PadRead();

    // Quit if both Select and Start pressed
    if (padStatus & PAD1select && padStatus & PAD1start) break;


    SetScrollSpeed();

    // Set rects
    tleft.x = 0;
    tleft.y = 256;
    tleft.w = offsetx;
    tleft.h = offsety;
    tright.x = offsetx;
    tright.y = 256;
    tright.w = 320 - offsetx;
    tright.h = offsety;
    bleft.x = 0;
    bleft.y = 256 + offsety;
    bleft.w = offsetx;
    bleft.h = 256 - offsety;
    bright.x = offsetx;
    bright.y = 256 + offsety;
    bright.w = 320 - offsetx;
    bright.h = 256 - offsety;


    // Wait for a vertical blank
    VSync(0);

    // Copy virtual screen parts to visible area
    MoveImage(&bright, 0, 0);
    if (offsetx)
      MoveImage(&bleft, 320 - offsetx, 0);
    if (offsety)
      MoveImage(&tright, 0, 256 - offsety);
    if (offsetx && offsety)
      MoveImage(&tleft, 320 - offsetx, 256 - offsety);

    DrawSync(0);
    GsSwapDispBuff();

    // Increment offsets (scroll!) and wrap around
    offsetx += incx;
    offsety += incy;
    if (offsetx >= 320) offsetx -= 320;
    else if (offsetx < 0) offsetx += 320;
    if (offsety >= 256) offsety -= 256;
    else if (offsety < 0) offsety += 256;
  }

  ResetGraph(0);
}



// Draw a 'picture' on the virtual screen (0,256)-(320,512)
// (50 Random rectangles)
void DrawPicture()
{
  RECT scr;                                    // Virtual screen
  RECT box;
  int i;

  scr.x = 0;
  scr.y = 256;
  scr.w = 320;
  scr.h = 256;

  ClearImage(&scr, 0, 0, 0);

  for (i=0; i < 50; i++)
  {
    box.x = rand()%290 + scr.x;
    box.y = rand()%226 + scr.y;
    box.w = 10 + rand()%30;
    box.h = 10 + rand()%30;
    ClearImage(&box, rand()%256, rand()%256, rand()%256);
  }
}





// Tests PAD for type and movement level
void SetScrollSpeed()
{
  if ((*(bb0+1) >> 4) == 4)                   // Digital PAD connected
  {
    if (padStatus & PAD1left)
      if (incx > -MAXSPEED) incx--;
    if (padStatus & PAD1right)
      if (incx < MAXSPEED) incx++;
    if (padStatus & PAD1up)
      if (incy > -MAXSPEED) incy--;
    if (padStatus & PAD1down)
      if (incy < MAXSPEED) incy++;
  }
  else                                        // Analog PAD connected
  if ( (*(bb0+1) >> 4) == 7 || (*(bb0+1) >> 4) == 5 )
  {
    if (PAD1lh < (128 - NULLZONE) || PAD1lh > (128+NULLZONE))
    {
      if (PAD1lh < 128)
        incx = (MAXSPEED * (PAD1lh - 128 + NULLZONE)) / (128 - NULLZONE);
      else
        incx = (MAXSPEED * (PAD1lh - 128 - NULLZONE)) / (128 - NULLZONE);
    }
    else
      incx = 0;
    if (PAD1lv < (128 - NULLZONE) || PAD1lv > (128 + NULLZONE))
    {
      if (PAD1lv < 128)
        incy = (MAXSPEED * (PAD1lv - 128 + NULLZONE)) / (128 - NULLZONE);
      else
        incy = (MAXSPEED * (PAD1lv - 128 - NULLZONE)) / (128 - NULLZONE);
    }
    else
      incy = 0;
  }
}












// ****** PAD routines ******

// call once only in program initialisation
void PadInit (void)
{
  GetPadBuf(&bb0, &bb1);
}

// call once per VSync(0)
u_long PadRead(void)
{
  // Get analog values
  PAD1rh = *(bb0+4);
  PAD1rv = *(bb0+5);
  PAD1lh = *(bb0+6);
  PAD1lv = *(bb0+7);
  return(~(*(bb0+3) | *(bb0+2) << 8 | *(bb1+3) << 16 | *(bb1+2) << 24));
}