src/zline.h

   1 {
   2         int n, dx, dy, sx, pp_inc_1, pp_inc_2;
   3         register int a;
   4         register PIXEL *pp;
   5 #if defined(INTERP_RGB) || TGL_FEATURE_RENDER_BITS == 24
   6         register unsigned int r, g, b;
   7 #endif
   8 #ifdef INTERP_RGB
   9         register unsigned int rinc, ginc, binc;
  10 #endif
  11 #ifdef INTERP_Z
  12         register unsigned short *pz;
  13         int zinc;
  14         register int z, zz;
  15 #endif
  16
  17         if (p1->y > p2->y || (p1->y == p2->y && p1->x > p2->x)) {
  18                 ZBufferPoint *tmp;
  19                 tmp = p1;
  20                 p1 = p2;
  21                 p2 = tmp;
  22         }
  23         sx = zb->xsize;
  24         pp = (PIXEL *) ((char *) zb->pbuf + zb->linesize * p1->y + p1->x * PSZB);
  25 #ifdef INTERP_Z
  26         pz = zb->zbuf + (p1->y * sx + p1->x);
  27         z = p1->z;
  28 #endif
  29
  30         dx = p2->x - p1->x;
  31         dy = p2->y - p1->y;
  32 #ifdef INTERP_RGB
  33         r = p2->r << 8;
  34         g = p2->g << 8;
  35         b = p2->b << 8;
  36 #elif TGL_FEATURE_RENDER_BITS == 24
  37         /* for 24 bits, we store the colors in different variables */
  38         r = p2->r >> 8;
  39         g = p2->g >> 8;
  40         b = p2->b >> 8;
  41 #endif
  42
  43 #ifdef INTERP_RGB
  44 #define RGB(x) x
  45 #if TGL_FEATURE_RENDER_BITS == 24
  46 #define RGBPIXEL pp[0] = r >> 16, pp[1] = g >> 16, pp[2] = b >> 16
  47 #else
  48 #define RGBPIXEL *pp = RGB_TO_PIXEL(r >> 8,g >> 8,b >> 8)
  49 #endif
  50 #else /* INTERP_RGB */
  51 #define RGB(x)
  52 #if TGL_FEATURE_RENDER_BITS == 24
  53 #define RGBPIXEL pp[0] = r, pp[1] = g, pp[2] = b
  54 #else
  55 #define RGBPIXEL *pp = color
  56 #endif
  57 #endif /* INTERP_RGB */
  58
  59 #ifdef INTERP_Z
  60 #define ZZ(x) x
  61 #define PUTPIXEL()                              \
  62         {                                               \
  63                 zz=z >> ZB_POINT_Z_FRAC_BITS;           \
  64                 if (ZCMP(zz,*pz))  {                    \
  65                         RGBPIXEL;       \
  66                         *pz=zz;                                         \
  67                 }                                               \
  68         }
  69 #else /* INTERP_Z */
  70 #define ZZ(x)
  71 #define PUTPIXEL() RGBPIXEL
  72 #endif /* INTERP_Z */
  73
  74 #define DRAWLINE(dx,dy,inc_1,inc_2) \
  75         n=dx;\
  76         ZZ(zinc=(p2->z-p1->z)/n);\
  77         RGB(rinc=((p2->r-p1->r) << 8)/n;\
  78                         ginc=((p2->g-p1->g) << 8)/n;\
  79                         binc=((p2->b-p1->b) << 8)/n);\
  80         a=2*dy-dx;\
  81         dy=2*dy;\
  82         dx=2*dx-dy;\
  83         pp_inc_1 = (inc_1) * PSZB;\
  84         pp_inc_2 = (inc_2) * PSZB;\
  85         do {\
  86                 PUTPIXEL();\
  87                 ZZ(z+=zinc);\
  88                 RGB(r+=rinc;g+=ginc;b+=binc);\
  89                 if (a>0) { pp=(PIXEL *)((char *)pp + pp_inc_1); ZZ(pz+=(inc_1));  a-=dx; }\
  90                 else { pp=(PIXEL *)((char *)pp + pp_inc_2); ZZ(pz+=(inc_2)); a+=dy; }\
  91         } while (--n >= 0);
  92
  93         /* fin macro */
  94
  95         if (dx == 0 && dy == 0) {
  96                 PUTPIXEL();
  97         } else if (dx > 0) {
  98                 if (dx >= dy) {
  99                         DRAWLINE(dx, dy, sx + 1, 1);
 100                 } else {
 101                         DRAWLINE(dy, dx, sx + 1, sx);
 102                 }
 103         } else {
 104                 dx = -dx;
 105                 if (dx >= dy) {
 106                         DRAWLINE(dx, dy, sx - 1, -1);
 107                 } else {
 108                         DRAWLINE(dy, dx, sx - 1, sx);
 109                 }
 110         }
 111 }
 112
 113 #undef INTERP_Z
 114 #undef INTERP_RGB
 115
 116 /* internal defines */
 117 #undef DRAWLINE
 118 #undef PUTPIXEL
 119 #undef ZZ
 120 #undef RGB
 121 #undef RGBPIXEL