/*
 * Render a cylindrical slide rule in Postscript
 * (Otis King model L lookalike).
 *
 * Copyright (c) 2001 Peter Monta <pmonta@pmonta.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <stdio.h>
#include <math.h>

#define N 20        /* number of helix turns in a scale-decade */

#define XS 74.592   /* circumference of upper scale */
#define YS 49.324   /* height of a scale-decade */

/*
 * draw a Postscript line
 */

void line(double x1,double y1,double x2,double y2)
{ printf("%f %f moveto %f %f lineto stroke\n",x1*XS,y1*YS,x2*XS,y2*YS); }

/*
 * draw Postscript text
 */

void text(double x,double y,char* s)
{ printf("%f %f moveto (%s) show\n",x*XS,y*YS,s); }

/*
 * draw a tick mark, with text if it's a major tick (type 0)
 */

void tick(double v,int t,int log,int dir)
{ double x,vorig;
  char s[128];
  vorig=v;
  if (log)
    v = log10(v);
  x = N*v - (int)(N*v);
  switch (t) {
    case 0:
      line(x,v,x,v+dir*0.017);
      if (log)
        sprintf(s,"%3.0f",100.0*vorig);
      else
        sprintf(s,"%03.0f",1000.0*vorig);
      text(x-0.012,v+((dir==1)?0.015:-0.038),s);
      break;
    case 1:
      line(x,v,x,v+dir*0.012);
      break;
    case 2:
      line(x,v,x,v+dir*0.008);
      break;
    case 3:
      line(x,v,x,v+dir*0.017);
      if (log)
        sprintf(s,"%3.0f",10.0*vorig);
      else
        sprintf(s,"%03.0f",0.0);
      text(x-0.012,v+((dir==1)?0.015:-0.038),s);
      break; } }

typedef struct {
  int n;
  double begin;
  double incr;
  int type;
} tick_style;

#define NTICK 10

tick_style tick_tab[NTICK] = {
  { 100,  1.00, 0.01, 0 },    /* major ticks */
  { 75,   2.00, 0.02, 0 },
  { 130,  3.50, 0.05, 0 },
  { 24,   1.000, 0.005, 1 },  /* semiminor ticks */
  { 200,  2.000, 0.010, 1 },
  { 120,  1.000, 0.001, 2 },  /* minor ticks */
  { 440,  1.120, 0.002, 2 },
  { 400,  2.000, 0.005, 2 },
  { 600,  4.000, 0.010, 2 },
  { 1,   10.000, 0.000, 3 },  /* final "overflow" tick */
};

/*
 * draw a complete log scale
 */

void scale(int dir)
{ int i,b;
  printf("0.076 setlinewidth\n");
  for (i=0; i<N; i++)
    line(0,((double)i)/N,1.0,((double)(i+1))/N);
  printf("0.076 setlinewidth\n");
  for (b=0; b<NTICK; b++)
    for (i=0; i<tick_tab[b].n; i++)
      tick(tick_tab[b].begin+i*tick_tab[b].incr,tick_tab[b].type,1,dir); }

#define NLIN_TICK 4

tick_style lin_tick_tab[NTICK] = {
  { 200,  0.00, 0.005,  0 },    /* major ticks */
  { 1000, 0.00, 0.001,  1 },    /* semiminor ticks */
  { 2000, 0.00, 0.0005, 2 },   /* minor ticks */
  { 1,    1.00, 0.000,  3 },  /* final "overflow" tick */
};

/*
 * draw a complete linear scale
 */

void lin_scale()
{ int i,b;
  printf("0.076 setlinewidth\n");
  for (i=0; i<N; i++)
    line(0,((double)i)/N,1.0,((double)(i+1))/N);
  printf("0.076 setlinewidth\n");
  for (b=0; b<NLIN_TICK; b++)
    for (i=0; i<lin_tick_tab[b].n; i++)
      tick(lin_tick_tab[b].begin+i*lin_tick_tab[b].incr,lin_tick_tab[b].type,0,1); }

#define BIAS 0.015   /* offset scale endpoints from trim edge */

void upper_scale()
{ int tx;
  printf("gsave\n");
  printf("0 setlinewidth\n");
  printf("19 145 translate\n");
  line(-BIAS,-1.31,-BIAS,-1.26);
  line(-BIAS,2.42,-BIAS,2.47);
  line(1-BIAS,-1.31,1-BIAS,-1.26);
  line(1-BIAS,2.42,1-BIAS,2.47);
  printf("newpath\n");
  printf("%f %f moveto\n",-0.05*XS,-1.21*YS);
  printf("%f %f lineto\n",1.05*XS,-1.21*YS);
  printf("%f %f lineto\n",1.05*XS,2.37*YS);
  printf("%f %f lineto\n",-0.05*XS,2.37*YS);
  printf("closepath clip\n");
  for (tx=-1; tx<=1; tx++) {
    printf("gsave\n");
    printf("%f 0 translate\n",tx*XS);
    lin_scale();
    printf("grestore\n"); }
  printf("0 %f translate\n",1.075*YS);
  for (tx=-1; tx<=1; tx++) {
    printf("gsave\n");
    printf("%f 0 translate\n",tx*XS);
    scale(1);
    printf("grestore\n"); }
  printf("grestore\n"); }

void lower_scale()
{ int tx;
  printf("gsave\n");
  printf("0 setlinewidth\n");
  printf("117 198 translate\n");
  printf("1.014 1 scale\n");
  line(-BIAS,-1.4,-BIAS,-1.35);
  line(-BIAS,1.185,-BIAS,1.235);
  line(1-BIAS,-1.4,1-BIAS,-1.35);
  line(1-BIAS,1.185,1-BIAS,1.235);
  printf("newpath\n");
  printf("%f %f moveto\n",-0.05*XS,-1.3*YS);
  printf("%f %f lineto\n",1.05*XS,-1.3*YS);
  printf("%f %f lineto\n",1.05*XS,1.135*YS);
  printf("%f %f lineto\n",-0.05*XS,1.135*YS);
  printf("closepath clip\n");
  for (tx=-1; tx<=1; tx++) {
    printf("gsave\n");
    printf("%f 0 translate\n",tx*XS);
    scale(-1);
    printf("grestore\n"); }
  printf("grestore\n"); }

int directions_num = 29;

char* directions_strings[] = {
  "Directions:",
  "",
  "Cut out the pieces using the trim lines.  A paper trimmer is recommended,",
  "but scissors may be used if the trim lines are joined by pencil and",
  "straightedge, then carefully cut inside the line so no pencil shows in",
  "the final article.",
  "",
  "Wrap the lower scale and upper scale into cylinders and secure along the",
  "seam with transparent tape \\(the matte-surface 3M Magic tape works well\\).",
  "The tape should go on the outside of the upper scale and on the inside of",
  "the lower scale, so that when they are telescoped there will be a smooth,",
  "paper-to-paper sliding action.  Make sure the small tick marks keep their",
  "uniform spacing across the seam---gaps or overlaps will degrade the",
  "rule's accuracy.",
  "",
  "Telescope the upper scale into the lower scale.  The lower scale is",
  "horizontally stretched by 1.2 percent to allow this to happen \\(this value",
  "is appropriate to the thickness of ordinary laser printer paper\\).",
  "",
  "Wrap the cursor around the assembly. Aim for a slightly looser fit than",
  "the two main tubes, then tape.  There is no harm in an overlapped joint",
  "for this part, and it is much easier to make and adjust.",
  "",
  "Set or read the scales from directly above, not from an angle.  The",
  "cursor mark rides slightly above the upper scale, so parallax must be",
  "eliminated for best accuracy.",
  "",
  "Directions for use, and much other lore besides, can be found at",
  "http://www.svpal.org/~dickel/OK/OtisKing.html",
};

void directions()
{ int i;
  printf("/Palatino findfont 2.2 scalefont setfont\n");
  for (i=0; i<directions_num; i++) {
    printf("20 %f moveto\n",76.0-2.1*i);
    printf("(%s) show\n",directions_strings[i]); } }

int cursor_num = 7;

char* cursor_strings[] = {
  "Cylindrical slide rule",
  "\\(Otis King model L format\\)",
  "",
  "Peter Monta     January 2001",
  "http://www.pmonta.com/sliderules",
  "http://www.svpal.org/~dickel",
  "  /OK/OtisKing.html",
};

void cursor()
{ int i;
  printf("gsave\n");
  printf("154 70 translate\n");
  printf("0 setlinewidth\n");
  line(-0.7,0.785,-0.65,0.785);
  line(0.65,0.785,0.7,0.785);
  line(-0.7,-0.785,-0.65,-0.785);
  line(0.65,-0.785,0.7,-0.785);
  line(-0.6,-0.83,-0.6,0.83);
  line(-0.6,0.83,0.6,0.83);
  line(0.6,0.83,0.6,-0.83);
  line(0.6,-0.83,-0.6,-0.83);
  printf("0.076 setlinewidth\n");
  line(0,0.6,0,0.83);
  line(0,-0.6,0,-0.83);
  printf("/Palatino findfont 2.8 scalefont setfont\n");
  printf("-6 -21 translate\n");
  printf("90 rotate\n");
  for (i=0; i<cursor_num; i++) {
    printf("0 %f moveto\n",-2.9*i);
    printf("(%s) show\n",cursor_strings[i]); }
  printf("grestore\n"); }

int main()
{ printf("%%!PS-Adobe-2.0\n");
  printf("2.834646 2.834646 scale\n");  /* millimeters */
  printf("/Palatino findfont 1.78 scalefont setfont\n");

  upper_scale();
  lower_scale();
  cursor();
  directions();

  printf("showpage\n");

  return 0; }