/* bezier.c This is a shell file only. It does some of the tedious in/out
for you, but all the real mathematics is missing.  */

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

#define ERRORFILE stderr

#define CONTROL_SIZE 200  /* maximum number of control points in one curve */
#define STEP 10        /* the number of  t  steps for each Bezier segment */
#define POWER_LIMIT 10 /* how far we calculate the geometric
					series on page 176  */

point wind_low  = {0,0};
point wind_high = {1,1};

main()
{
int no_input_errors = 1;
int N,Q,BBB=1,III=1,BB=1,M;
point B_controls[CONTROL_SIZE];   /* for B-spline control points  Ai */
point I_controls[CONTROL_SIZE];   /* for Interpolant control points  Gi */
point current_point;
char in_filename[50], out_filename[50];
char text[100];
char current_line[100];
FILE *fp_in;
int inside_Bspline = 0;
int inside_interpolant = 0;
int show_polygon = 0;

fp_in = stdin;
strcpy(in_filename,"standard input");

N=0;
while (no_input_errors)
{
	if (N>0)
	{
		Q = fscanf(fp_in,"\n");
	}
	Q = fscanf(fp_in,"%[^\n]",current_line);
				if (Q <= 0) {error_1(N,in_filename); break;}
	if (inside_Bspline) {switch(current_line[0])
	{
		case 'E': /*End B-spline */
			inside_Bspline=0;
			B_spline(B_controls,M,show_polygon);
			fprintf(ERRORFILE,"Line %d ends %d-th spline.\n",
								N+1,BBB);
			printf("%%    End %d-th B-spline:  %.45s\n",
							BBB,text);
			strcpy(text,"");  /* clears the string `text' */
			BBB++;
			show_polygon=0;
			break;
		case 'c': /* control point */
			Q = sscanf(current_line,"c%F%F",
			&B_controls[M].x_coord,&B_controls[M].y_coord);
				if (Q <= 1) {error_a(N+1,in_filename);
						no_input_errors=0; break;}
			M += 1;
			break;
		case 's'/*show control poygon */:
			show_polygon=1; break;
		case '%'/*comment*/:
                case 'N'/*Name of picture*/:
                case 'z'/* insert comment in log file */:
		case '\\'/*Escape*/:    /* escape saved for later */
		case 'W'/*Width*/:
			printf("%s\n",current_line);
			break;
		default:
			error_A(N+1,in_filename); no_input_errors=0;
			break;
	}}
	else if (inside_interpolant) {switch(current_line[0])
	{
		case 'F'/*End Interpolating curve*/:
			inside_interpolant=0;
			Interpolating_curve(I_controls,M,show_polygon);
			fprintf(ERRORFILE,"Line %d ends %d-th Interpolant.\n",
								N+1,III);
			printf("%%    End %d-th Interpolating curve:  %.45s\n",
							III,text);
			strcpy(text,"");  /* clears the string `text' */
			III++;
			show_polygon=0;
			break;
		case 'c': /* control point */
/* now */
			Q = sscanf(current_line,"c%F%F",
			&I_controls[M].x_coord,&I_controls[M].x_coord);
				if (Q <= 1) {error_a(N+1,in_filename);
						no_input_errors=0; break;}
			M += 1;
			break;
		case '%'/*comment*/:
                case 'N'/*Name of picture*/:
                case 'z'/* insert comment in log file */:
		case '\\'/*Escape*/:    /* escape saved for later */
		case 'W'/*Width*/:
		printf("%s\n",current_line);
			break;
		default:
			error_B(N+1,in_filename); no_input_errors=0;
			break;
	}}
	else {switch(current_line[0])
	{
		case 'B'/*Begin B-spline*/:
			fprintf(ERRORFILE,"Line %d begins %d-th ",N+1,BBB);
			fprintf(ERRORFILE,"B-spline.\n");
			Q = sscanf(current_line,"B%[^\n]",text);
			printf("%%    Begin %d-th B-spline:  %.45s\n",
							BBB,text);
			inside_Bspline = 1;
			M = 0;
			break;
		case 'A'/*Begin interpolant*/:
			fprintf(ERRORFILE,"Line %d begins %d-th ",N+1,III);
			fprintf(ERRORFILE,"interpolating curve.\n");
			Q = sscanf(current_line,"A%[^\n]",text);
			printf("%%    Begin %d-th interpolating curve:",III);
			printf("  %.45s\n", text);
			inside_interpolant = 1;
			M = 0;
			break;
		case 'E'/*End B-spline*/:
			error_E(N+1,in_filename); no_input_errors=0;
			break;
		case 'F'/*End interpolating curve*/:
			error_F(N+1,in_filename); no_input_errors=0;
			break;
		case 'c': /* control point */
			error_a1(N+1,in_filename); no_input_errors=0;
			break;
		case '%'/*comment*/:
                case 'N'/*Name of picture*/:
                case 'z'/* insert comment in log file */:
		case '\\'/*Escape*/:    /* escape saved for later */
		case 'm'/*move*/: 
		case 'l'/*line*/:
		case 'P': /* path (to be filled) */
		case 'L': /* point in path */
		case 'q': /* terminate and fill path */
		case 'Q': /* terminate, fill path, and stroke */
		case 'w'/*window*/:
		case 'W'/*Width*/:
		case 't'/*text, small*/:
		case 'x'/*text, medium*/:
		case 'T'/*text, large*/:
                case 'd'/*dot*/:
                case 'g'/*gray_level*/:
                case 'C'/*color	*/:
			printf("%s\n",current_line);
			break;
		default:
			fprintf(ERRORFILE,"Data of unknown type in line ");
			fprintf(ERRORFILE,"%d; ignored up to newline.\n",N+1);
			break;
	}}
	N++;
}
fclose(fp_in);
}

Interpolating_curve(I_controls,M,show_polygon)
int M,show_polygon; point_3 I_controls[];   /*I_controls = G_i in the notes */
{
point_3 B_controls[CONTROL_SIZE];   /* for B-spline control points  Ai */
if (M<3)
{
	fprintf(ERRORFILE,
		"At least three control points needed. Spline disregarded.");
	return;
}

/* Calculation of B_controls (Ai) from I_controls (Gi) as on pages
                                        174-176                       */

/* Many lines deleted, winding up with something like :

for(i=1;i<N;i++) for(l=0;l<N-1;l++)   B_controls[i] =    .........    */

B_spline(B_controls,M,show_polygon);
}


B_spline(B_controls,M,show_polygon)
int M,show_polygon; point_3 B_controls[];
{
int i;
point_3 P0, P1, P2, P3;
if (M<3)
{
	fprintf(ERRORFILE,
		"At least three control points needed. Spline disregarded.");
	return;
}
/* Now, repeated calculation of Bezier control points  P0, P1, P2, P3
from the B_controls[i] (i.e. the  Ai), according to the scheme described
on pages  172-175,  resulting in  N-1  commands of the form:    

	bezier(P0,P1,P2,P3);                                    */
}

bezier(q,r,s,t)
point_3 q,r,s,t;
{
/* here you have to invoke Equation (3.13) on page 167 (or you could use
   Exercise 1 on page 168).                                        */
/* Print a cubic curve ---- consisting of  STEP  small segments  ---
   according to methods that we have already done.                  */

}

error_1(N,in_filename)
int N; char in_filename[];
{
	fprintf(ERRORFILE,"\nSuccessfully read ");
	fprintf(ERRORFILE,"%d lines of data from \"%s\"\n",N,in_filename);
}

error_E(N,in_filename)
int N; char in_filename[];
{
	fprintf(ERRORFILE,"Data error in line %d. Cannot ",N);
	fprintf(ERRORFILE,"end spline data before beginning.");
	fprintf(ERRORFILE,"\nProgram terminated.\n");
}

error_F(N,in_filename)
int N; char in_filename[];
{
	fprintf(ERRORFILE,"Data error in line %d. Cannot ",N);
	fprintf(ERRORFILE,"end spline data before beginning.");
	fprintf(ERRORFILE,"\nProgram terminated.\n");
}

error_a1(N,in_filename)
int N; char in_filename[];
{
	fprintf(ERRORFILE,"Data error in line %d. Control ",N);
	fprintf(ERRORFILE,"points allowed only between  A  or  B  and  E.");
	fprintf(ERRORFILE,"\nProgram terminated.\n");
}

error_a(N)
int N;
{
	printf("\nControl point error in line %d. Must give three",N);
	printf(" coordinates.\nProgram terminated.\n");
}

error_A(N,in_filename)
int N; char in_filename[];
{
	fprintf(ERRORFILE,"Data error in line %d. Must ",N);
	fprintf(ERRORFILE,"have control points until end of spline.");
	fprintf(ERRORFILE,"\nProgram terminated.\n");
}

error_B(N,in_filename)
int N; char in_filename[];
{
	fprintf(ERRORFILE,"Data error in line %d. Must ",N);
	fprintf(ERRORFILE,"have control points until end of spline.");
	fprintf(ERRORFILE,"\nProgram terminated.\n");
}
error_w0(N)
int N;
{
        fprintf(ERRORFILE,"\nWindow error in line %d. Must give six window"
								,N);
        fprintf(ERRORFILE," coordinates.\nProgram terminated.\n");
}
error_w1(N)
int N;
{
        fprintf(ERRORFILE,"\nWindow error in line %d. Window must have ");
	fprintf(ERRORFILE,"non-zero",N);
        fprintf(ERRORFILE," dimensions.\nProgram terminated.\n");
}
error_l(N)
int N;
{
        fprintf(ERRORFILE,"\nLine error in line %d. Must give three line",N);
        fprintf(ERRORFILE," coordinates.\nProgram terminated.\n");
}
error_m(N)
int N;
{
        fprintf(ERRORFILE,"\nMove error in line %d. Must give three move",N);
        fprintf(ERRORFILE," coordinates.\nProgram terminated.\n");
}
error_r(N)
int N;
{
        fprintf(ERRORFILE,"\nError in line %d. Must give two rotation",N);
        fprintf(ERRORFILE," angles.\nProgram terminated.\n");
}
error_v(N)
int N;
{
        fprintf(ERRORFILE,"\nViewpoint error in line %d. Must give three",N);
        fprintf(ERRORFILE," viewpoint coordinates.\nProgram terminated.\n");
}
error_M(N)
int N;
{
        fprintf(ERRORFILE,"\nMotion error in line %d. Must give three",N);
        fprintf(ERRORFILE," motion coordinates.\nProgram terminated.\n");
}