The Utilities Experience/The Utilities Experience - Volume 1.iso/software/misc/o-z/x-windows/mesa-amiwin/src/interp.h

C/C++ Source or Header | 1995-11-30 | 4.6 KB | 199 lines

/* interp.h */

/*
 * Mesa 3-D graphics library
 * Version:  1.2
 * Copyright (C) 1995  Brian Paul  ([e-mail])
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the Free
 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */


/*
$Id: interp.h,v 1.6 1995/10/23 21:27:54 brianp Exp $

$Log: interp.h,v $
 * Revision 1.6  1995/10/23  21:27:54  brianp
 * new GLubyte interpolation using fixed point arithmetic
 *
 * Revision 1.5  1995/06/12  15:43:57  brianp
 * separate GLint and GLubyte interpolation functions
 *
 * Revision 1.4  1995/06/02  13:59:01  brianp
 * faster GL_INTERPOLATE() macro
 *
 * Revision 1.3  1995/05/22  20:59:34  brianp
 * Release 1.2
 *
 * Revision 1.2  1995/03/04  19:25:29  brianp
 * 1.1 beta revision
 *
 * Revision 1.1  1995/02/27  22:20:16  brianp
 * Initial revision
 *
 */


#ifndef INTERP_H
#define INTERP_H



extern void gl_interpolate_i( GLint n, GLint y0, GLint y1, GLint yspan[] );


extern void gl_interpolate_ub( GLint n, GLint y0, GLint y1, GLubyte yspan[] );


extern void gl_interpolate_4ub( GLint n,
                                GLint a0, GLint a1, GLubyte aspan[],
                                GLint b0, GLint b1, GLubyte bspan[],
                                GLint c0, GLint c1, GLubyte cspan[],
                                GLint d0, GLint d1, GLubyte dspan[] );


extern void gl_interp_texcoords( GLuint n,
                 GLfloat eyez0, GLfloat eyez1,
                 GLfloat winz0, GLfloat winz1,
                 GLfloat s0, GLfloat s1,
                 GLfloat t0, GLfloat t1,
                 GLfloat s[], GLfloat t[], GLfloat *z );


#ifdef DEBUG

#define GL_INTERPOLATE_I(N,Y0,Y1,YSPAN)   gl_interpolate_i(N,Y0,Y1,YSPAN)

#define GL_INTERPOLATE_UB(N,Y0,Y1,YSPAN)  gl_interpolate_ub(N,Y0,Y1,YSPAN)

#else

#define GL_INTERPOLATE_I(N,Y0,Y1,YSPAN)    \
{                    \
   switch (N) {                \
      case 1:                \
     YSPAN[0] = Y0;            \
     break;                \
      case 2:                \
     YSPAN[0] = Y0;            \
     YSPAN[1] = Y1;            \
     break;                \
      case 3:                \
     YSPAN[0] = Y0;            \
     YSPAN[1] = ((Y0)+(Y1)) >> 1;    \
     YSPAN[2] = Y1;            \
     break;                \
      default:                \
     if (Y0==Y1) {            \
        register GLint i;        \
        for (i=0;i<(N);i++) {    \
           YSPAN[i] = Y0;        \
        }                \
     }                \
     else {                \
        register GLint i;        \
        register GLint dx, dy;    \
        register GLint a, b, d;    \
        register GLint yy;        \
        register GLint qa, qb;    \
        dx = (N)-1;            \
        dy = (Y1) - (Y0);        \
        qa = dy / dx;        \
        dy = dy % dx;        \
        if (dy<0) {            \
           dy = -dy;        \
           qb = qa - 1;        \
        }                \
        else {            \
           qb = qa + 1;        \
        }                \
        a = dy + dy;        \
        d = a - dx;            \
        b = d - dx;            \
        yy = Y0;            \
        for (i=0;i<(N);i++) {    \
           YSPAN[i] = yy;        \
           if (d<0) {        \
          d += a;        \
          yy += qa;        \
           }            \
           else {            \
          d += b;        \
          yy += qb;        \
           }            \
        }                \
     }                \
   }                    \
}



#define GL_INTERPOLATE_UB(N,Y0,Y1,YSPAN)    \
    if ((N)>1) {                \
       int yy0 = (Y0) << 8;            \
       int yy1 = (Y1) << 8;            \
       int dyy = (yy1-yy0) / ((int)(N)-1);    \
       int ii;                \
       for (ii=0;ii<(N);ii++) {        \
          YSPAN[ii] = yy0 >> 8;        \
          yy0 += dyy;            \
       }                    \
    }                    \
    else {                    \
       YSPAN[0] = Y0;            \
    }



#endif  /*DEBUG*/



#define GL_INTERPOLATE_4UB( N, A0,A1,A, B0,B1,B, C0,C1,C, D0,D1,D )    \
    if ((N)<2) {                \
       A[0] = A0;                \
       B[0] = B0;                \
       C[0] = C0;                \
       D[0] = D0;                \
    }                    \
    else if ((N)==2) {            \
       A[0] = A0;  A[1] = A1;        \
       B[0] = B0;  B[1] = B1;        \
       C[0] = C0;  C[1] = C1;        \
       D[0] = D0;  D[1] = D1;        \
    }                    \
    else {                    \
       int a0, da, b0, db, c0, dc, d0,dd;    \
       int ii, nn = (int) (N) - 1;        \
       a0 = (A0) << 8;            \
       da = (((A1)<<8)-a0) / nn;        \
       b0 = (B0) << 8;            \
       db = (((B1)<<8)-b0) / nn;        \
       c0 = (C0) << 8;            \
       dc = (((C1)<<8)-c0) / nn;        \
       d0 = (D0) << 8;            \
       dd = (((D1)<<8)-d0) / nn;        \
       for (ii=0;ii<(N);ii++) {        \
          A[ii] = a0 >> 8;    a0+=da;        \
          B[ii] = b0 >> 8;    b0+=db;        \
          C[ii] = c0 >> 8;    c0+=dc;        \
          D[ii] = d0 >> 8;    d0+=dd;        \
       }                    \
    }


#endif  /* INTERP_H */