align.c
1.74 KB
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/**************************************************************************
* *
* Copyright (C) 1994, Silicon Graphics, Inc. *
* *
* These coded instructions, statements, and computer programs contain *
* unpublished proprietary information of Silicon Graphics, Inc., and *
* are protected by Federal copyright law. They may not be disclosed *
* to third parties or copied or duplicated in any form, in whole or *
* in part, without the prior written consent of Silicon Graphics, Inc. *
* *
**************************************************************************/
#include "guint.h"
/*
* S = sin (a)
* C = cos (a)
* H = sqrt (X*X + Z*Z)
*
* [ v ] [ C S ] [ 1 ] [ -Z/H X/H ]
* [ -S C ] [ H Y ] [ 1 ]
* [ 1 ] [ -Y H ] [ -X/H -Z/H ]
* [ 1 ] [ 1 ] [ 1 ]
*
*/
void guAlignF(float mf[4][4], float a, float x, float y, float z)
{
static float dtor = 3.1415926 / 180.0;
float s, c, h, hinv;
guNormalize(&x, &y, &z);
a *= dtor;
s = sinf (a);
c = cosf (a);
h = sqrtf (x*x + z*z);
guMtxIdentF(mf);
if (h != 0) {
hinv = 1 / h;
mf[0][0] = (-z*c - s*y*x) * hinv;
mf[1][0] = (z*s - c*y*x) * hinv;
mf[2][0] = -x;
mf[3][0] = 0;
mf[0][1] = s*h;
mf[1][1] = c*h;
mf[2][1] = -y;
mf[3][1] = 0;
mf[0][2] = (c*x - s*y*z) * hinv;
mf[1][2] = (-s*x - c*y*z) * hinv;
mf[2][2] = -z;
mf[3][2] = 0;
mf[0][3] = 0;
mf[1][3] = 0;
mf[2][3] = 0;
mf[3][3] = 1;
} else {
/* XXX: should do this right */
}
}
void guAlign(Mtx *m, float a, float x, float y, float z)
{
Matrix mf;
guAlignF(mf, a, x, y, z);
guMtxF2L(mf, m);
}