scummvm/tinygl/ztriangle.cpp

#include <stdlib.h>
#include "tinygl/zbuffer.h"

#define ZCMP(z,zpix) ((z) >= (zpix))

void ZB_fillTriangleFlat(ZBuffer *zb,
			 ZBufferPoint *p0,ZBufferPoint *p1,ZBufferPoint *p2)
{
    int color;

#define INTERP_Z

#define DRAW_INIT()				\
{						\
  color=RGB_TO_PIXEL(p2->r,p2->g,p2->b);	\
}
  
#define PUT_PIXEL(_a)				\
{						\
    zz=z >> ZB_POINT_Z_FRAC_BITS;		\
    if (ZCMP(zz,pz[_a])) {				\
      pp[_a]=color;				\
      pz[_a]=zz;				\
    }						\
    z+=dzdx;					\
}

#include "ztriangle.h"
}

/*
 * Smooth filled triangle.
 * The code below is very tricky :)
 */

void ZB_fillTriangleSmooth(ZBuffer *zb,
			   ZBufferPoint *p0,ZBufferPoint *p1,ZBufferPoint *p2)
{
        int _drgbdx;

#define INTERP_Z
#define INTERP_RGB

#define SAR_RND_TO_ZERO(v,n) (v / (1<<n))

#define DRAW_INIT() 				\
{						\
  _drgbdx=(SAR_RND_TO_ZERO(drdx,6) << 22) & 0xFFC00000;		\
  _drgbdx|=SAR_RND_TO_ZERO(dgdx,5) & 0x000007FF;		\
  _drgbdx|=(SAR_RND_TO_ZERO(dbdx,7) << 12) & 0x001FF000; 	\
}


#define PUT_PIXEL(_a)				\
{						\
    zz=z >> ZB_POINT_Z_FRAC_BITS;		\
    if (ZCMP(zz,pz[_a])) {				\
      tmp=rgb & 0xF81F07E0;			\
      pp[_a]=tmp | (tmp >> 16);			\
      pz[_a]=zz;				\
    }						\
    z+=dzdx;					\
    rgb=(rgb+drgbdx) & ( ~ 0x00200800);		\
}

#define DRAW_LINE()							   \
{									   \
  register unsigned short *pz;					   \
  register PIXEL *pp;					   \
  register unsigned int tmp,z,zz,rgb,drgbdx;				   \
  register int n;							   \
  n=(x2 >> 16) - x1;							   \
  pp=pp1+x1;								   \
  pz=pz1+x1;								   \
  z=z1;									   \
  rgb=(r1 << 16) & 0xFFC00000;						   \
  rgb|=(g1 >> 5) & 0x000007FF;						   \
  rgb|=(b1 << 5) & 0x001FF000;						   \
  drgbdx=_drgbdx;							   \
  while (n>=3) {							   \
    PUT_PIXEL(0);							   \
    PUT_PIXEL(1);							   \
    PUT_PIXEL(2);							   \
    PUT_PIXEL(3);							   \
    pz+=4;								   \
    pp+=4;								   \
    n-=4;								   \
  }									   \
  while (n>=0) {							   \
    PUT_PIXEL(0);							   \
    pz+=1;								   \
    pp+=1;								   \
    n-=1;								   \
  }									   \
}

#include "ztriangle.h"
}

void ZB_setTexture(ZBuffer *zb,PIXEL *texture)
{
    zb->current_texture=texture;
}

void ZB_fillTriangleMapping(ZBuffer *zb,
			    ZBufferPoint *p0,ZBufferPoint *p1,ZBufferPoint *p2)
{
    PIXEL *texture;

#define INTERP_Z
#define INTERP_ST

#define DRAW_INIT()				\
{						\
  texture=zb->current_texture;			\
}

#define PUT_PIXEL(_a)				\
{						\
   zz=z >> ZB_POINT_Z_FRAC_BITS;		\
     if (ZCMP(zz,pz[_a])) {				\
       pp[_a]=texture[((t & 0x3FC00000) | s) >> 14];	\
       pz[_a]=zz;				\
    }						\
    z+=dzdx;					\
    s+=dsdx;					\
    t+=dtdx;					\
}

#include "ztriangle.h"
}

void ZB_fillTriangleMappingPerspective(ZBuffer *zb,
                            ZBufferPoint *p0,ZBufferPoint *p1,ZBufferPoint *p2)
{
    PIXEL *texture;
    float fdzdx,fndzdx,ndszdx,ndtzdx;
    int _drgbdx;

#define INTERP_Z
#define INTERP_RGB
#define INTERP_STZ

#define NB_INTERP 8

#define SAR_RND_TO_ZERO(v,n) (v / (1<<n))

#define DRAW_INIT()				\
{						\
  texture=zb->current_texture;\
  fdzdx=(float)dzdx;\
  fndzdx=NB_INTERP * fdzdx;\
  ndszdx=NB_INTERP * dszdx;\
  ndtzdx=NB_INTERP * dtzdx;\
  _drgbdx=(SAR_RND_TO_ZERO(drdx,6) << 22) & 0xFFC00000;		\
  _drgbdx|=SAR_RND_TO_ZERO(dgdx,5) & 0x000007FF;		\
  _drgbdx|=(SAR_RND_TO_ZERO(dbdx,7) << 12) & 0x001FF000; 	\
}


#define PUT_PIXEL(_a)				\
{						\
   zz=z >> ZB_POINT_Z_FRAC_BITS;		\
     if (ZCMP(zz,pz[_a])) {				\
       tmp=rgb & 0xF81F07E0;			\
	   unsigned int light = tmp | (tmp >> 16); \
       PIXEL pixel = *(PIXEL *)((char *)texture+ \
          (((t & 0x3FC00000) | (s & 0x003FC000)) >> (17 - PSZSH)));\
       unsigned int c_r = (pixel & 0xF800) >> 8;    \
       unsigned int c_g = (pixel & 0x07E0) >> 3;    \
       unsigned int c_b = (pixel & 0x001F) << 3;    \
       unsigned int l_r = (light & 0xF800) >> 8;    \
       unsigned int l_g = (light & 0x07E0) >> 3;    \
       unsigned int l_b = (light & 0x001F) << 3;    \
       c_r = (c_r * l_r) / 256; \
       c_g = (c_g * l_g) / 256; \
       c_b = (c_b * l_b) / 256; \
       pixel = ((c_r & 0xF8) << 8) | ((c_g & 0xFC) << 3) | (c_b >> 3); \
       pp[_a]=pixel;            \
       pz[_a]=zz;				\
    }						\
    z+=dzdx;					\
    s+=dsdx;					\
    t+=dtdx;					\
    rgb=(rgb+drgbdx) & ( ~ 0x00200800);		\
}

#define DRAW_LINE()				\
{						\
  register unsigned short *pz;		\
  register PIXEL *pp;		\
  register unsigned int s,t,z,zz,rgb,drgbdx;	\
  register int n,dsdx,dtdx;		\
  float sz,tz,fz,zinv; \
  n=(x2>>16)-x1;                             \
  fz=(float)z1;\
  zinv=(float)(1.0 / fz);\
  pp=(PIXEL *)((char *)pp1 + x1 * PSZB); \
  pz=pz1+x1;					\
  z=z1;						\
  sz=sz1;\
  tz=tz1;\
  rgb=(r1 << 16) & 0xFFC00000;						   \
  rgb|=(g1 >> 5) & 0x000007FF;						   \
  rgb|=(b1 << 5) & 0x001FF000;						   \
  drgbdx=_drgbdx;							   \
  while (n>=(NB_INTERP-1)) {						   \
    {\
      float ss,tt;\
      ss=(sz * zinv);\
      tt=(tz * zinv);\
      s=(int) ss;\
      t=(int) tt;\
      dsdx= (int)( (dszdx - ss*fdzdx)*zinv );\
      dtdx= (int)( (dtzdx - tt*fdzdx)*zinv );\
      fz+=fndzdx;\
      zinv=(float)(1.0 / fz);\
    }\
    PUT_PIXEL(0);							   \
    PUT_PIXEL(1);							   \
    PUT_PIXEL(2);							   \
    PUT_PIXEL(3);							   \
    PUT_PIXEL(4);							   \
    PUT_PIXEL(5);							   \
    PUT_PIXEL(6);							   \
    PUT_PIXEL(7);							   \
    pz+=NB_INTERP;							   \
    pp=(PIXEL *)((char *)pp + NB_INTERP * PSZB);\
    n-=NB_INTERP;							   \
    sz+=ndszdx;\
    tz+=ndtzdx;\
  }									   \
    {\
      float ss,tt;\
      ss=(sz * zinv);\
      tt=(tz * zinv);\
      s=(int) ss;\
      t=(int) tt;\
      dsdx= (int)( (dszdx - ss*fdzdx)*zinv );\
      dtdx= (int)( (dtzdx - tt*fdzdx)*zinv );\
    }\
  while (n>=0) {							   \
    PUT_PIXEL(0);							   \
    pz+=1;								   \
    pp=(PIXEL *)((char *)pp + PSZB);\
    n-=1;								   \
  }									   \
}
  
#include "ztriangle.h"
}