/*  FILENAME:  AALines.h  [revised 17 AUG 90]    AUTHOR:  Kelvin Thompson    DESCRIPTION:  Symbols and globals for the anti-aliased line      renderer.    #INCLUDED IN:      AAMain.c -- Calling routine for renderer.      AATables.c -- Initialization routines for lookup tables.      AALines.c -- Rendering code.*//* frame buffer to hold the anti-aliased line */#define xpix 60#define ypix 60extern char *fbuff;/* macros to access the frame buffer */#define PIXADDR(xx,yy) (fbuff+(yy)*xpix+(xx))#define PIXINC(dx,dy)  ((dy)*xpix+(dx))/* fixed-point data types and macros */typedef int FX;typedef unsigned int UFX;#define FX_FRACBITS 16  /* bits of fraction in FX format */#define FX_0        0   /* zero in fixed-point format */#define FLOAT_TO_FX(flt)  ((FX)((flt)*(1<<FX_FRACBITS)+0.5))/* some important constants */#define PI      3.1415926535897932384626433832795028841971693993751#define SQRT_2  1.4142135623730950488016887242096980785696718753769/* square-root function globals */extern UFX *sqrtfunc;extern int sqrtcells;extern int sqrtshift;#define SQRTFUNC(fxval)  (sqrtfunc[ (fxval) >> sqrtshift ])/* AA globals */extern float line_r;  /* line radius */extern float pix_r;   /* pixel radius */extern FX *coverage;extern int covercells;extern int covershift;#define COVERAGE(fxval) (coverage[ (fxval) >> covershift ])