/*----------------------------------------------------------------------  File    : wshades.c  Contents: Windows functions for color and grey shades allocation  Author  : Christian Borgelt  History : 28.01.2000 file created----------------------------------------------------------------------*/#include <stdio.h>#include <stdlib.h>#include <math.h>#include <assert.h>#include "wshades.h"/*----------------------------------------------------------------------  Preprocessor Definitions----------------------------------------------------------------------*/#define RGB_MAX   255                 /* maximum RGB value *//*----------------------------------------------------------------------  Auxiliary Functions----------------------------------------------------------------------*/static double intensity (double col){                               /* --- get rgb color intensity */  assert((col >= -2) && (col <= 3));  /* check the function argument */  if (col <= 0)   return 0;           /* intensity curve: */  if (col <  0.5) return 2*col;       /*   0.5 1.5        */  if (col <= 1.5) return 1;           /*    _____       1 */  if (col <  2)   return 4 -2*col;    /*   /     \_____ 0 */  return 0;                           /*  0   1   2   3   */}  /* intensity() *//*----------------------------------------------------------------------  Main Functions----------------------------------------------------------------------*/void shd_delete (SHADES *shds){                               /* --- delete color shades */  assert(shds);                 /* check the function argument */  free(shds->pixels[0]);        /* delete the pixel vectors */  free(shds);                   /* and the base structure */}  /* shd_delete() *//*--------------------------------------------------------------------*/SHADES* shd_create (double coloff, int colcnt, int shdbase, int shdcnt){                               /* --- create color shades */  int    i, k;                  /* loop variables, buffers */  SHADES *shds;                 /* created color shades */  double col, dc;               /* color and color difference */  double t;                     /* temporary buffer */  double red, green, blue;      /* RGB intensities */  PIXEL  **pp, *p;              /* to traverse the pixels */  if (shdcnt <= 0) shdcnt = 1;  /* check and adapt number of shades */  if (shdcnt > SHD_MAXCNT) shdcnt = SHD_MAXCNT;  coloff = fmod(coloff, 360);   /* compute color offset and */  if (coloff < 0) coloff += 360;/* ensure that it is positive */  k    = (colcnt > 0) ? colcnt : 1;  shds = (SHADES*)malloc(sizeof(SHADES) +(k-1) *sizeof(PIXEL*));  if (!shds) return NULL;       /* allocate the base structure */  shds->pixels[0] = p = (PIXEL*)calloc(k *shdcnt, sizeof(PIXEL));  if (!p) { free(shds); return NULL; }  for (pp = shds->pixels; --k > 0; )    *++pp = p += shdcnt;        /* allocate and organize vectors */  shds->coloff  = coloff;       /* and initialize other fields */  shds->colcnt  = (colcnt <= 0) ? 0 : colcnt;  shds->shdbase = (shdbase == SHD_BLACK) ? SHD_BLACK : SHD_WHITE;  shds->shdcnt  = shdcnt;  /* --- grey shades --- */  if (colcnt <= 0) {            /* if no color shades requested */    for (p += i = shdcnt; --i >= 0; ) {      t = (shdcnt > 1)          /* compute the intensity value */        ? ((double)i/(shdcnt-1)) *(RGB_MAX+0.99) : (RGB_MAX +0.99);      k = (int)floor(t);        /* compute RGB values of grey shade */      if (shdbase != SHD_BLACK) k = RGB_MAX -k;      *--p = RGB(k, k, k);      /* if to shade from white, invert */    }                           /* and store the computed grey */    return shds;                /* return the created grey shades */  }  /* --- color shades --- */  coloff /= 120;                /* compute color offset from angle */  dc      = 3.0/colcnt;         /* and color difference as a fraction */  for (pp = shds->pixels, k = 0; k < colcnt; k++, pp++) {    col   = k *dc +coloff;      /* traverse the colors */    col  -= t = col -floor(col);    col   = (((2*t -3)*t +2)*t +fmod(col, 3));    red   = intensity((col >= 2) ? col -2 : col +1);    green = intensity(col);     /* transform the color and */    blue  = intensity(col -1);  /* compute the RGB intensities */    for (p = *pp +(i = shdcnt); --i >= 0; ) {      t = (shdcnt > 1)          /* compute the scaling factor */        ? ((double)i/(shdcnt-1)) *(RGB_MAX+0.99) : (RGB_MAX +0.99);      if (shdbase == SHD_BLACK){/* if shading from black */        *--p = RGB((WORD)floor(red   *t),                   (WORD)floor(green *t),                   (WORD)floor(blue  *t)); }      else {                    /* if shading from white */        *--p = RGB(RGB_MAX -(WORD)floor((1 -red)   *t),                   RGB_MAX -(WORD)floor((1 -green) *t),                   RGB_MAX -(WORD)floor((1 -blue)  *t));      }                         /* compute the RGB value and */    }                           /* store it in the color vector */  }  return shds;                  /* return the created color shades */}  /* shd_create() */