/* * The 3D Studio File Format Library * Copyright (C) 1996-2007 by Jan Eric Kyprianidis * All rights reserved. * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation; either version 2.1 of the License, or (at * your option) any later version. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public * License for more details. * * You should have received a copy of the GNU Lesser General Public License * along with this program; if not, write to the Free Software Foundation, * Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * * $Id: vector.c,v 1.12 2007/06/20 17:04:09 jeh Exp $ */ #include #include /*! * \defgroup vector Vector Mathematics */ /*! * \typedef Lib3dsVector * \ingroup vector */ /*! * Clear a vector to zero. * * \param c Vector to clear. * * \ingroup vector */ void lib3ds_vector_zero(Lib3dsVector c) { int i; for (i=0; i<3; ++i) { c[i]=0.0f; } } /*! * Copy a vector. * * \param dest Destination vector. * \param src Source vector. * * \ingroup vector */ void lib3ds_vector_copy(Lib3dsVector dest, Lib3dsVector src) { int i; for (i=0; i<3; ++i) { dest[i]=src[i]; } } /*! * Negate a vector. * * \param c Vector to negate. * * \ingroup vector */ void lib3ds_vector_neg(Lib3dsVector c) { int i; for (i=0; i<3; ++i) { c[i]=-c[i]; } } /*! * Add two vectors. * * \param c Result. * \param a First addend. * \param b Second addend. * * \ingroup vector */ void lib3ds_vector_add(Lib3dsVector c, Lib3dsVector a, Lib3dsVector b) { int i; for (i=0; i<3; ++i) { c[i]=a[i]+b[i]; } } /*! * Subtract two vectors. * * \param c Result. * \param a Addend. * \param b Minuend. * * \ingroup vector */ void lib3ds_vector_sub(Lib3dsVector c, Lib3dsVector a, Lib3dsVector b) { int i; for (i=0; i<3; ++i) { c[i]=a[i]-b[i]; } } /*! * Multiply a vector by a scalar. * * \param c Vector to be multiplied. * \param k Scalar. * * \ingroup vector */ void lib3ds_vector_scalar(Lib3dsVector c, Lib3dsFloat k) { int i; for (i=0; i<3; ++i) { c[i]*=k; } } /*! * Compute cross product. * * \param c Result. * \param a First vector. * \param b Second vector. * * \ingroup vector */ void lib3ds_vector_cross(Lib3dsVector c, Lib3dsVector a, Lib3dsVector b) { c[0]=a[1]*b[2] - a[2]*b[1]; c[1]=a[2]*b[0] - a[0]*b[2]; c[2]=a[0]*b[1] - a[1]*b[0]; } /*! * Compute dot product. * * \param a First vector. * \param b Second vector. * * \return Dot product. * * \ingroup vector */ Lib3dsFloat lib3ds_vector_dot(Lib3dsVector a, Lib3dsVector b) { return(a[0]*b[0] + a[1]*b[1] + a[2]*b[2]); } /*! * Compute square of vector. * * Computes x*x + y*y + z*z. * * \param c Vector to square. * * \return Square of vector. * * \ingroup vector */ Lib3dsFloat lib3ds_vector_squared(Lib3dsVector c) { return(c[0]*c[0] + c[1]*c[1] + c[2]*c[2]); } /*! * Compute length of vector. * * Computes |c| = sqrt(x*x + y*y + z*z) * * \param c Vector to compute. * * \return Length of vector. * * \ingroup vector */ Lib3dsFloat lib3ds_vector_length(Lib3dsVector c) { return((Lib3dsFloat)sqrt(c[0]*c[0] + c[1]*c[1] + c[2]*c[2])); } /*! * Normalize a vector. * * Scales a vector so that its length is 1.0. * * \param c Vector to normalize. * * \ingroup vector */ void lib3ds_vector_normalize(Lib3dsVector c) { Lib3dsFloat l,m; l=(Lib3dsFloat)sqrt(c[0]*c[0] + c[1]*c[1] + c[2]*c[2]); if (fabs(l)=c[1]) && (c[0]>=c[2])) { c[0]=1.0f; c[1]=c[2]=0.0f; } else if (c[1]>=c[2]) { c[1]=1.0f; c[0]=c[2]=0.0f; } else { c[2]=1.0f; c[0]=c[1]=0.0f; } } else { m=1.0f/l; c[0]*=m; c[1]*=m; c[2]*=m; } } /*! * Compute a vector normal to two line segments. * * Computes the normal vector to the lines b-a and b-c. * * \param n Returned normal vector. * \param a Endpoint of first line. * \param b Base point of both lines. * \param c Endpoint of second line. * * \ingroup vector */ void lib3ds_vector_normal(Lib3dsVector n, Lib3dsVector a, Lib3dsVector b, Lib3dsVector c) { Lib3dsVector p,q; lib3ds_vector_sub(p,c,b); lib3ds_vector_sub(q,a,b); lib3ds_vector_cross(n,p,q); lib3ds_vector_normalize(n); } /*! * Multiply a point by a transformation matrix. * * Applies the given transformation matrix to the given point. With some * transformation matrices, a vector may also be transformed. * * \param c Result. * \param m Transformation matrix. * \param a Input point. * * \ingroup vector */ void lib3ds_vector_transform(Lib3dsVector c, Lib3dsMatrix m, Lib3dsVector a) { c[0]= m[0][0]*a[0] + m[1][0]*a[1] + m[2][0]*a[2] + m[3][0]; c[1]= m[0][1]*a[0] + m[1][1]*a[1] + m[2][1]*a[2] + m[3][1]; c[2]= m[0][2]*a[0] + m[1][2]*a[1] + m[2][2]*a[2] + m[3][2]; } /*! * Compute a point on a cubic spline. * * Computes a point on a parametric Bezier spline. * * \param c Result. * \param a First endpoint of the spline. * \param p First tangent vector of the spline. * \param q Second tangent vector of the spline. * \param b Second endpoint of the spline. * \param t Spline parameter [0. 1.] * * \ingroup vector */ void lib3ds_vector_cubic(Lib3dsVector c, Lib3dsVector a, Lib3dsVector p, Lib3dsVector q, Lib3dsVector b, Lib3dsFloat t) { Lib3dsDouble x,y,z,w; x=2*t*t*t - 3*t*t + 1; y=-2*t*t*t + 3*t*t; z=t*t*t - 2*t*t + t; w=t*t*t - t*t; c[0]=(Lib3dsFloat)(x*a[0] + y*b[0] + z*p[0] + w*q[0]); c[1]=(Lib3dsFloat)(x*a[1] + y*b[1] + z*p[1] + w*q[1]); c[2]=(Lib3dsFloat)(x*a[2] + y*b[2] + z*p[2] + w*q[2]); } /*! * c[i] = min(c[i], a[i]); * * Computes minimum values of x,y,z independently. * * \ingroup vector */ void lib3ds_vector_min(Lib3dsVector c, Lib3dsVector a) { int i; for (i=0; i<3; ++i) { if (a[i]c[i]) { c[i] = a[i]; } } } /*! * \ingroup vector */ void lib3ds_vector_dump(Lib3dsVector c) { fprintf(stderr, "%f %f %f\n", c[0], c[1], c[2]); }