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/* LOCKVC Version 3.6 (c) 1994, 1995, 1997 by Matthias Straub */
/* shadow-password option added by Ed Beaumont */
/* integer math derived from a patch by Jeff Epler */
/* this file was released under GPL */
/* see COPYING for details */
#define FPBITS 10
#define FM(x,y) (((x)*(y))>>FPBITS)
#define FM3(x,y,z) (((x)*(y)*(z))>>(2*FPBITS))
#define SIN(x) (feld->sintab[(x)&4095])
#define COS(x) SIN(x+256*4)
#define MAXNUMSTARS 2000
#define SFLENGTH 1024 /* twice DIST */
#define SFWIDTH 400
#define SFHEIGHT 400
#define DIST 512 /* should be a power of 2 for speed */
#define SCRX 320 /* .EQ. vga-mode */
#define SCRY 240 /* .EQ. vga-mode */
#include <math.h>
#include <vga.h>
#include <stdlib.h>
#include <stdio.h>
#include "lockvc.h"
struct field
{
int xr[MAXNUMSTARS];
int yr[MAXNUMSTARS];
int zr[MAXNUMSTARS];
int xbuf[2][MAXNUMSTARS];
int ybuf[2][MAXNUMSTARS];
int s,t,u;
int sintab[4096];
int numstars;
int stride;
};
void mksintab(struct field *feld)
{
int i;
for(i=0;i<4096;i++)
{
feld->sintab[i]=(int)(sin(i*M_PI*2.0/4096)*1024);
}
}
void initfield(struct field *feld)
{
int i;
for (i=0;i<(feld->numstars);i++)
{
feld->xr[i]=SFWIDTH-random()%(SFWIDTH<<1);
feld->yr[i]=SFHEIGHT-random()%(SFHEIGHT<<1);
feld->zr[i]=random()%SFLENGTH-SFLENGTH/2;
}
}
void initpalette()
{
int j;
for (j=0;j<64;j++)
{
vga_setpalette(j,j,j,j);
}
for (j=64;j<=80;j++)
{
vga_setpalette(j,63,63,63);
}
}
void plotfield(struct field *feld)
{
static int q,qq,x2,y2,z2,xl,yl,i;
static int offset=0;
static int page=1;
int IS11,IS12,IS13,IS21,IS22,IS23,IS31,IS32,IS33;
/* looks weird, doesn't it? */
/* it's just the */
/* product of 3 less */
/* spectacular matrices */
/* that's what one year */
/* linear algebra class */
/* was for */
IS11 = FM(COS(feld->s),COS(feld->t));
IS12 = FM(SIN(feld->s),COS(feld->t));
IS13 = -SIN(feld->t);
IS21 = -FM(SIN(feld->s),COS(feld->u))+FM3(COS(feld->s),SIN(feld->t),SIN(feld->u));
IS22 = FM(COS(feld->s),COS(feld->u))+FM3(SIN(feld->s),SIN(feld->t),SIN(feld->u));
IS23 = FM(COS(feld->t),SIN(feld->u));
IS31 = FM(SIN(feld->s),SIN(feld->u))+FM3(COS(feld->s),SIN(feld->t),COS(feld->u));
IS32 = -FM(COS(feld->s),SIN(feld->u))+FM3(SIN(feld->s),SIN(feld->t),COS(feld->u));
IS33 = FM(COS(feld->t),COS(feld->u));
page=1-page;
offset=SCRY-offset;
vga_setdisplaystart((SCRY-offset)*SCRX);
vga_waitretrace();
vga_setcolor(0);
for (i=0;i<(feld->numstars);i++)
{
x2=feld->xbuf[page][i];
y2=feld->ybuf[page][i];
if (x2<SCRX && y2 < (SCRY+offset) && x2>=0 && y2 >= offset)
{
vga_drawpixel(x2,y2);
}
}
for (i=0;i<(feld->numstars);i++)
{
feld->zr[i]=feld->zr[i]+feld->stride;
if (feld->zr[i]>SFLENGTH/2) feld->zr[i]=-SFLENGTH/2;
z2 = (IS13*feld->xr[i]+IS23*feld->yr[i]+IS33*feld->zr[i])>>FPBITS;
if (z2!=DIST) q=(DIST-z2);
else q=1;
qq=q>>1;
x2 = (DIST*((int)(IS11*feld->xr[i]+IS21*feld->yr[i]+IS31*feld->zr[i])>>FPBITS)+qq)/q;
y2 = (DIST*((int)(IS12*feld->xr[i]+IS22*feld->yr[i]+IS32*feld->zr[i])>>FPBITS)+qq)/q;
feld->xbuf[page][i]=((x2+2)>>2)+SCRX/2;
feld->ybuf[page][i]=SCRY/2-((y2+2)>>2)+offset;
xl=feld->xbuf[page][i];
yl=feld->ybuf[page][i];
if (xl >=0 && xl <SCRX && yl >=offset && yl < (SCRY+offset) && z2<=DIST && z2>=-DIST)
{
vga_setcolor(40+(z2*40)/DIST);
vga_drawpixel(xl,yl);
}
}
if(vga_getkey()!=0 && vga_getkey()!=-1) authenticate();
}
void starfield(int argc, char **argv)
{
int j;
static struct field this;
if(argc ==4)
{
this.numstars=atoi(argv[2]);
this.stride=atoi(argv[3]);
if(this.numstars<1 || this.numstars>MAXNUMSTARS)
{printf("Number of stars must be between 1 and %i.\n",MAXNUMSTARS);exit(-1);}
if(this.stride<0 || this.stride >100)
{
printf("Stride must be between 0 and 100.\n");exit(-1);
}
}
else
{
this.numstars=700;
this.stride=9;
}
vga_setmode(G320x240x256);
if(vga_claimvideomemory(SCRX*SCRY*2))
{ printf("vga_claimvideomemoy refused\n"); exit(-1);}
signals();
initfield (&this);
mksintab(&this);
initpalette();
for (j=0;j<200;j++)
{
plotfield (&this);
}
while(1)
{
for (j=0;j<2048;j++)
{
plotfield (&this);
this.s+=2;
this.t+=5;
this.u+=7;
}
}
}
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