149 lines
4.3 KiB
C
149 lines
4.3 KiB
C
/* Copyright 1988, Brown Computer Graphics Group. All Rights Reserved. */
|
|
|
|
/* --------------------------------------------------------------------------
|
|
* This file contains routines that operate on matrices and vectors, or
|
|
* vectors and vectors.
|
|
* -------------------------------------------------------------------------*/
|
|
|
|
/* #include "sphigslocal.h" */
|
|
|
|
/* -------------------------- Static Routines ---------------------------- */
|
|
|
|
/* ------------------------- Internal Routines --------------------------- */
|
|
|
|
/* -------------------------- Public Routines ---------------------------- */
|
|
|
|
/*
|
|
* Multiplies a vector by a matrix, setting the result vector.
|
|
* It assumes all homogeneous coordinates are 1.
|
|
* The two vectors involved may be the same.
|
|
*/
|
|
|
|
#include <Math/mat3.h>
|
|
|
|
#ifndef TRUE
|
|
# define TRUE 1
|
|
#endif
|
|
|
|
#ifndef FALSE
|
|
# define FALSE 0
|
|
#endif
|
|
|
|
|
|
void
|
|
MAT3mult_vec(double *result_vec, register double *vec, register double (*mat)[4])
|
|
{
|
|
MAT3vec tempvec;
|
|
register double *temp = tempvec;
|
|
|
|
temp[0] = vec[0] * mat[0][0] + vec[1] * mat[1][0] +
|
|
vec[2] * mat[2][0] + mat[3][0];
|
|
temp[1] = vec[0] * mat[0][1] + vec[1] * mat[1][1] +
|
|
vec[2] * mat[2][1] + mat[3][1];
|
|
temp[2] = vec[0] * mat[0][2] + vec[1] * mat[1][2] +
|
|
vec[2] * mat[2][2] + mat[3][2];
|
|
|
|
MAT3_COPY_VEC(result_vec, temp);
|
|
}
|
|
|
|
/*
|
|
* Multiplies a vector of size 4 by a matrix, setting the result vector.
|
|
* The fourth element of the vector is the homogeneous coordinate, which
|
|
* may or may not be 1. If the "normalize" parameter is TRUE, then the
|
|
* result vector will be normalized so that the homogeneous coordinate is 1.
|
|
* The two vectors involved may be the same.
|
|
* This returns zero if the vector was to be normalized, but couldn't be.
|
|
*/
|
|
|
|
int
|
|
MAT3mult_hvec(double *result_vec, register double *vec, register double (*mat)[4], int normalize)
|
|
{
|
|
MAT3hvec tempvec;
|
|
double norm_fac;
|
|
register double *temp = tempvec;
|
|
register int ret = TRUE;
|
|
|
|
temp[0] = vec[0] * mat[0][0] + vec[1] * mat[1][0] +
|
|
vec[2] * mat[2][0] + vec[3] * mat[3][0];
|
|
temp[1] = vec[0] * mat[0][1] + vec[1] * mat[1][1] +
|
|
vec[2] * mat[2][1] + vec[3] * mat[3][1];
|
|
temp[2] = vec[0] * mat[0][2] + vec[1] * mat[1][2] +
|
|
vec[2] * mat[2][2] + vec[3] * mat[3][2];
|
|
temp[3] = vec[0] * mat[0][3] + vec[1] * mat[1][3] +
|
|
vec[2] * mat[2][3] + vec[3] * mat[3][3];
|
|
|
|
/* Normalize if asked for, possible, and necessary */
|
|
if (normalize) {
|
|
if (MAT3_IS_ZERO(temp[3])) {
|
|
#ifndef THINK_C
|
|
fprintf (stderr,
|
|
"Can't normalize vector: homogeneous coordinate is 0");
|
|
#endif
|
|
ret = FALSE;
|
|
}
|
|
else {
|
|
norm_fac = 1.0 / temp[3];
|
|
MAT3_SCALE_VEC(result_vec, temp, norm_fac);
|
|
result_vec[3] = 1.0;
|
|
}
|
|
}
|
|
else MAT3_COPY_HVEC(result_vec, temp);
|
|
|
|
return(ret);
|
|
}
|
|
|
|
/*
|
|
* Sets the first vector to be the cross-product of the last two vectors.
|
|
*/
|
|
|
|
void
|
|
MAT3cross_product(double *result_vec, register double *vec1, register double *vec2)
|
|
{
|
|
MAT3vec tempvec;
|
|
register double *temp = tempvec;
|
|
|
|
temp[0] = vec1[1] * vec2[2] - vec1[2] * vec2[1];
|
|
temp[1] = vec1[2] * vec2[0] - vec1[0] * vec2[2];
|
|
temp[2] = vec1[0] * vec2[1] - vec1[1] * vec2[0];
|
|
|
|
MAT3_COPY_VEC(result_vec, temp);
|
|
}
|
|
|
|
/*
|
|
* Finds a vector perpendicular to vec and stores it in result_vec.
|
|
* Method: take any vector (we use <0,1,0>) and subtract the
|
|
* portion of it pointing in the vec direction. This doesn't
|
|
* work if vec IS <0,1,0> or is very near it. So if this is
|
|
* the case, use <0,0,1> instead.
|
|
* If "is_unit" is TRUE, the given vector is assumed to be unit length.
|
|
*/
|
|
|
|
#define SELECT .7071 /* selection constant (roughly .5*sqrt(2) */
|
|
|
|
void
|
|
MAT3perp_vec(double *result_vec, double *vec, int is_unit)
|
|
{
|
|
MAT3vec norm;
|
|
double dot;
|
|
|
|
MAT3_SET_VEC(result_vec, 0.0, 1.0, 0.0);
|
|
|
|
MAT3_COPY_VEC(norm, vec);
|
|
|
|
if (! is_unit) MAT3_NORMALIZE_VEC(norm, dot);
|
|
|
|
/* See if vector is too close to <0,1,0>. If so, use <0,0,1> */
|
|
if ((dot = MAT3_DOT_PRODUCT(norm, result_vec)) > SELECT || dot < -SELECT) {
|
|
result_vec[1] = 0.0;
|
|
result_vec[2] = 1.0;
|
|
dot = MAT3_DOT_PRODUCT(norm, result_vec);
|
|
}
|
|
|
|
/* Subtract off non-perpendicular part */
|
|
result_vec[0] -= dot * norm[0];
|
|
result_vec[1] -= dot * norm[1];
|
|
result_vec[2] -= dot * norm[2];
|
|
|
|
/* Make result unit length */
|
|
MAT3_NORMALIZE_VEC(result_vec, dot);
|
|
}
|