vbagx/source/vba/gba/Mode4.cpp

/*
Mode 4 is a 256 colour bitmap graphics mode with 2 swappable pages.
It has a single layer, background layer 2, the same size as the screen.
It doesn't support scrolling, flipping, rotation or tiles.

These routines only render a single line at a time, because of the way the GBA does events.
*/
#include "GBA.h"
#include "GBAGfx.h"
#include "Globals.h"

void mode4RenderLine()
{
  u16 *palette = (u16 *)paletteRAM;

  if(DISPCNT & 0x0080) {

	int x = 232;	//240 - 8  
	do{
		lineMix[x  ] =
		lineMix[x+1] =
		lineMix[x+2] =
		lineMix[x+3] =
		lineMix[x+4] =
		lineMix[x+5] =
		lineMix[x+6] =
		lineMix[x+7] = 0x7fff;
		x-=8;
	}while(x>=0);

    gfxLastVCOUNT = VCOUNT;
    return;
  }

  if(layerEnable & 0x400) {
    int changed = gfxBG2Changed;

    if(gfxLastVCOUNT > VCOUNT)
      changed = 3;

    gfxDrawRotScreen256(BG2CNT, BG2X_L, BG2X_H, BG2Y_L, BG2Y_H,
                        BG2PA, BG2PB, BG2PC, BG2PD,
                        gfxBG2X, gfxBG2Y, changed,
                        line2);
  }

  gfxDrawSprites(lineOBJ);

  u32 backdrop;
  if(customBackdropColor == -1) {
    backdrop = (READ16LE(&palette[0]) | 0x30000000);
  } else {
    backdrop = ((customBackdropColor & 0x7FFF) | 0x30000000);
  }

  for(int x = 0; x < 240; ++x) {
    u32 color = backdrop;
    u8 top = 0x20;

    if(line2[x] < backdrop) {
      color = line2[x];
      top = 0x04;
    }

    if((u8)(lineOBJ[x]>>24) < (u8)(color >> 24)) {
      color = lineOBJ[x];
      top = 0x10;
    }

    if((top & 0x10) && (color & 0x00010000)) {
      // semi-transparent OBJ
      u32 back = backdrop;
      u8 top2 = 0x20;

      if(line2[x] < backdrop) {
        back = line2[x];
        top2 = 0x04;
      }

      if(top2 & (BLDMOD>>8))
        color = gfxAlphaBlend(color, back,
                              coeff[COLEV & 0x1F],
                              coeff[(COLEV >> 8) & 0x1F]);
      else {
        switch((BLDMOD >> 6) & 3) {
        case 2:
          if(BLDMOD & top)
            color = gfxIncreaseBrightness(color, coeff[COLY & 0x1F]);
          break;
        case 3:
          if(BLDMOD & top)
            color = gfxDecreaseBrightness(color, coeff[COLY & 0x1F]);
          break;
        }
      }
    }

    lineMix[x] = color;
  }
  gfxBG2Changed = 0;
  gfxLastVCOUNT = VCOUNT;
}

void mode4RenderLineNoWindow()
{
  u16 *palette = (u16 *)paletteRAM;

  if(DISPCNT & 0x0080) {

	int x = 232;	//240 - 8  
	do{
		lineMix[x  ] =
		lineMix[x+1] =
		lineMix[x+2] =
		lineMix[x+3] =
		lineMix[x+4] =
		lineMix[x+5] =
		lineMix[x+6] =
		lineMix[x+7] = 0x7fff;
		x-=8;
	}while(x>=0);

    gfxLastVCOUNT = VCOUNT;
    return;
  }

  if(layerEnable & 0x400) {
    int changed = gfxBG2Changed;

    if(gfxLastVCOUNT > VCOUNT)
      changed = 3;

    gfxDrawRotScreen256(BG2CNT, BG2X_L, BG2X_H, BG2Y_L, BG2Y_H,
                        BG2PA, BG2PB, BG2PC, BG2PD,
                        gfxBG2X, gfxBG2Y, changed,
                        line2);
  }

  gfxDrawSprites(lineOBJ);

  u32 backdrop;
  if(customBackdropColor == -1) {
    backdrop = (READ16LE(&palette[0]) | 0x30000000);
  } else {
    backdrop = ((customBackdropColor & 0x7FFF) | 0x30000000);
  }

  for(int x = 0; x < 240; ++x) {
    u32 color = backdrop;
    u8 top = 0x20;

    if(line2[x] < backdrop) {
      color = line2[x];
      top = 0x04;
    }

    if((u8)(lineOBJ[x]>>24) < (u8)(color >> 24)) {
      color = lineOBJ[x];
      top = 0x10;
    }

    if(!(color & 0x00010000)) {
      switch((BLDMOD >> 6) & 3) {
      case 0:
        break;
      case 1:
        {
          if(top & BLDMOD) {
            u32 back = backdrop;
            u8 top2 = 0x20;

			if((top != 0x04) && line2[x] < backdrop) {
                back = line2[x];
                top2 = 0x04;
            }

            if((top != 0x10) && (u8)(lineOBJ[x]>>24) < (u8)(back >> 24)) {
                back = lineOBJ[x];
                top2 = 0x10;
            }

            if(top2 & (BLDMOD>>8))
              color = gfxAlphaBlend(color, back,
                                    coeff[COLEV & 0x1F],
                                    coeff[(COLEV >> 8) & 0x1F]);

          }
        }
        break;
      case 2:
        if(BLDMOD & top)
          color = gfxIncreaseBrightness(color, coeff[COLY & 0x1F]);
        break;
      case 3:
        if(BLDMOD & top)
          color = gfxDecreaseBrightness(color, coeff[COLY & 0x1F]);
        break;
      }
    } else {
      // semi-transparent OBJ
      u32 back = backdrop;
      u8 top2 = 0x20;

      if(line2[x] < back) {
        back = line2[x];
        top2 = 0x04;
      }

      if(top2 & (BLDMOD>>8))
        color = gfxAlphaBlend(color, back,
                              coeff[COLEV & 0x1F],
                              coeff[(COLEV >> 8) & 0x1F]);
      else {
        switch((BLDMOD >> 6) & 3) {
        case 2:
          if(BLDMOD & top)
            color = gfxIncreaseBrightness(color, coeff[COLY & 0x1F]);
          break;
        case 3:
          if(BLDMOD & top)
            color = gfxDecreaseBrightness(color, coeff[COLY & 0x1F]);
          break;
        }
      }
    }

    lineMix[x] = color;
  }
  gfxBG2Changed = 0;
  gfxLastVCOUNT = VCOUNT;
}

void mode4RenderLineAll()
{
  u16 *palette = (u16 *)paletteRAM;

  if(DISPCNT & 0x0080) {

	int x = 232;	//240 - 8  
	do{
		lineMix[x  ] =
		lineMix[x+1] =
		lineMix[x+2] =
		lineMix[x+3] =
		lineMix[x+4] =
		lineMix[x+5] =
		lineMix[x+6] =
		lineMix[x+7] = 0x7fff;
		x-=8;
	}while(x>=0);

    gfxLastVCOUNT = VCOUNT;
    return;
  }

  bool inWindow0 = false;
  bool inWindow1 = false;

  if(layerEnable & 0x2000) {
    u8 v0 = WIN0V >> 8;
    u8 v1 = WIN0V & 255;
    inWindow0 = ((v0 == v1) && (v0 >= 0xe8));
    if(v1 >= v0)
      inWindow0 |= (VCOUNT >= v0 && VCOUNT < v1);
    else
      inWindow0 |= (VCOUNT >= v0 || VCOUNT < v1);
  }
  if(layerEnable & 0x4000) {
    u8 v0 = WIN1V >> 8;
    u8 v1 = WIN1V & 255;
    inWindow1 = ((v0 == v1) && (v0 >= 0xe8));
    if(v1 >= v0)
      inWindow1 |= (VCOUNT >= v0 && VCOUNT < v1);
    else
      inWindow1 |= (VCOUNT >= v0 || VCOUNT < v1);
  }

  if(layerEnable & 0x400) {
    int changed = gfxBG2Changed;

    if(gfxLastVCOUNT > VCOUNT)
      changed = 3;

    gfxDrawRotScreen256(BG2CNT, BG2X_L, BG2X_H, BG2Y_L, BG2Y_H,
                        BG2PA, BG2PB, BG2PC, BG2PD,
                        gfxBG2X, gfxBG2Y, changed,
                        line2);
  }

  gfxDrawSprites(lineOBJ);
  gfxDrawOBJWin(lineOBJWin);

  u32 backdrop;
  if(customBackdropColor == -1) {
    backdrop = (READ16LE(&palette[0]) | 0x30000000);
  } else {
    backdrop = ((customBackdropColor & 0x7FFF) | 0x30000000);
  }

  u8 inWin0Mask = WININ & 0xFF;
  u8 inWin1Mask = WININ >> 8;
  u8 outMask = WINOUT & 0xFF;

  for(int x = 0; x < 240; ++x) {
    u32 color = backdrop;
    u8 top = 0x20;
    u8 mask = outMask;

    if(!(lineOBJWin[x] & 0x80000000)) {
      mask = WINOUT >> 8;
    }

    if(inWindow1) {
      if(gfxInWin1[x])
        mask = inWin1Mask;
    }

    if(inWindow0) {
      if(gfxInWin0[x]) {
        mask = inWin0Mask;
      }
    }

    if((mask & 4) && (line2[x] < backdrop)) {
      color = line2[x];
      top = 0x04;
    }

    if((mask & 16) && ((u8)(lineOBJ[x]>>24) < (u8)(color >>24))) {
      color = lineOBJ[x];
      top = 0x10;
    }

    if(color & 0x00010000) {
      // semi-transparent OBJ
      u32 back = backdrop;
      u8 top2 = 0x20;

      if((mask & 4) && line2[x] < back) {
        back = line2[x];
        top2 = 0x04;
      }

      if(top2 & (BLDMOD>>8))
        color = gfxAlphaBlend(color, back,
                              coeff[COLEV & 0x1F],
                              coeff[(COLEV >> 8) & 0x1F]);
      else {
        switch((BLDMOD >> 6) & 3) {
        case 2:
          if(BLDMOD & top)
            color = gfxIncreaseBrightness(color, coeff[COLY & 0x1F]);
          break;
        case 3:
          if(BLDMOD & top)
            color = gfxDecreaseBrightness(color, coeff[COLY & 0x1F]);
          break;
        }
      }
    } else if(mask & 32) {
      switch((BLDMOD >> 6) & 3) {
      case 0:
        break;
      case 1:
        {
          if(top & BLDMOD) {
            u32 back = backdrop;
            u8 top2 = 0x20;

			if((mask & 4) && (top != 0x04) && (line2[x] < backdrop)) {
                back = line2[x];
                top2 = 0x04;
            }

            if((mask & 16) && (top != 0x10) && (u8)(lineOBJ[x]>>24) < (u8)(back >> 24)) {
                back = lineOBJ[x];
                top2 = 0x10;
            }

            if(top2 & (BLDMOD>>8))
              color = gfxAlphaBlend(color, back,
                                    coeff[COLEV & 0x1F],
                                    coeff[(COLEV >> 8) & 0x1F]);
          }
        }
        break;
      case 2:
        if(BLDMOD & top)
          color = gfxIncreaseBrightness(color, coeff[COLY & 0x1F]);
        break;
      case 3:
        if(BLDMOD & top)
          color = gfxDecreaseBrightness(color, coeff[COLY & 0x1F]);
        break;
      }
    }

    lineMix[x] = color;
  }
  gfxBG2Changed = 0;
  gfxLastVCOUNT = VCOUNT;
}