/* vect3d.c */

/* Routines to manipulate 3 dimensional vectors.  All these routines
 * should work even if the input and output vectors are the same.
 */

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <GL/gl.h>
#include "vect3d.h"

#if defined(__cplusplus) || defined(c_plusplus)
#define class c_class
#endif

void (*errfunc)(char *) = 0;

void seterrorfunc(void (*func)(char *))
{
    errfunc = func;
}

void error(char *s)
{
    if (errfunc)
	(*errfunc)(s);
    else {
	fprintf(stderr, s); 
	fprintf(stderr, "\n");
	exit(1);
    }
}

void diff3(GLdouble p[3], GLdouble q[3], GLdouble diff[3])
{
    diff[0] = p[0] - q[0];
    diff[1] = p[1] - q[1];
    diff[2] = p[2] - q[2];
}

void add3(GLdouble p[3], GLdouble q[3], GLdouble sum[3])
{
    sum[0] = p[0] + q[0];
    sum[1] = p[1] + q[1];
    sum[2] = p[2] + q[2];
}

void scalarmult(GLdouble s, GLdouble v[3], GLdouble vout[3])
{
    vout[0] = v[0]*s;
    vout[1] = v[1]*s;
    vout[2] = v[2]*s;
}

GLdouble dot3(GLdouble p[3], GLdouble q[3])
{
    return p[0]*q[0] + p[1]*q[1] + p[2]*q[2];
}

GLdouble length3(GLdouble v[3])
{
    return sqrt(v[0]*v[0] + v[1]*v[1] + v[2]*v[2]);
}

GLdouble dist3(GLdouble p[3], GLdouble q[3])
{
    GLdouble d[3];

    diff3(p, q, d);
    return length3(d);
}

void copy3(GLdouble old[3], GLdouble new_c[3])
{
    new_c[0] = old[0], new_c[1] = old[1], new_c[2] = old[2];
}

void crossprod(GLdouble v1[3], GLdouble v2[3], GLdouble prod[3])
{
    GLdouble p[3];	/* in case prod == v1 or v2 */

    p[0] = v1[1]*v2[2] - v2[1]*v1[2];
    p[1] = v1[2]*v2[0] - v2[2]*v1[0];
    p[2] = v1[0]*v2[1] - v2[0]*v1[1];
    prod[0] = p[0]; prod[1] = p[1]; prod[2] = p[2];
}

void normalize(GLdouble v[3])
{
    GLdouble d;

    d = sqrt(v[0]*v[0]+v[1]*v[1]+v[2]*v[2]);
    if (d == 0.0) {
        error("normalize: zero length vector");
	v[0] = d = 1.0;
    }
    d = 1/d;
    v[0] *= d; v[1] *= d; v[2] *= d;
}

void print3(GLdouble v[3])
{
    GLdouble len;

    len = length3(v);
    printf("(%g %g %g); len: %g\n", v[0], v[1], v[2], len);
}

void printmat3(GLdouble m[3][3])
{
    int i, j;

    for (i=0; i<3; i++) {
	for (j=0; j<3; j++)
	    printf("%7.4f  ", m[i][j]);
	printf("\n");
    }
}

void identifymat3(GLdouble m[3][3])
{
    int i, j;

    for (i=0; i<3; i++)
	for (j=0; j<3; j++)
	    m[i][j] = (i == j) ? 1.0 : 0.0;
}

void copymat3(GLdouble *to, GLdouble *from)
{
    int i;

    for (i=0; i<9; i++) {
	*to++ = *from++;
    }
}

void xformvec3(GLdouble v[3], GLdouble m[3][3], GLdouble vm[3])
{
    GLdouble result[3];	/* in case v == vm */
    int i;

    for (i=0; i<3; i++) {
	result[i] = v[0]*m[0][i] + v[1]*m[1][i] + v[2]*m[2][i];
    }
    for (i=0; i<3; i++) {
	vm[i] = result[i];
    }
}

long samepoint(GLdouble p1[3], GLdouble p2[3])
{
    if (p1[0] == p2[0] && p1[1] == p2[1] && p1[2] == p2[2])
	return 1;
    return 0;
}

void perpnorm(GLdouble p1[3], GLdouble p2[3], GLdouble p3[3], GLdouble n[3])
{
    GLdouble d1[3], d2[3];

    diff3(p2, p1, d1);
    diff3(p2, p3, d2);
    crossprod(d1, d2, n);
    normalize(n);
}

