OOTriangle.h

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/*
 
OOTriangle.h
 
Mathematical framework for Oolite.
 
Oolite
Copyright (C) 2004-2013 Giles C Williams and contributors
 
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
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 General Public License for more details.
 
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA.
 
*/
 
 
#ifndef INCLUDED_OOMATHS_h
    #error Do not include OOTriangle.h directly; include OOMaths.h.
#else
 
 
typedef struct
{
    Vector      v[3];
} Triangle;
 
 
/* Calculate normal for triangle. */
OOINLINE Vector calculateNormalForTriangle(Triangle *ioTriangle) NONNULL_FUNC;
 
/* Generate a triangle from three vertices. */
OOINLINE Triangle make_triangle(Vector v0, Vector v1, Vector v2) CONST_FUNC;
 
/* resolve vector in arbitrary ijk vectors */
OOINLINE Vector resolveVectorInIJK(Vector v0, Triangle ijk);
 
/* Test whether triangle's area is 0. */
OOINLINE bool OOTriangleIsDegenerate(Triangle tri) CONST_FUNC;
 
 
/*** Only inline definitions beyond this point ***/
 
OOINLINE Triangle make_triangle(Vector v0, Vector v1, Vector v2)
{
    return (Triangle){{ v0, v1, v2 }};
}
 
 
OOINLINE Vector calculateNormalForTriangle(Triangle *tri)
{
    Vector v01 = vector_subtract(tri->v[1], tri->v[0]);
    Vector v12 = vector_subtract(tri->v[2], tri->v[1]);
    return cross_product(v01, v12);
}
 
 
OOINLINE Vector resolveVectorInIJK(Vector v0, Triangle ijk)
{
    Vector result;
    result.x = dot_product(v0, ijk.v[0]);
    result.y = dot_product(v0, ijk.v[1]);
    result.z = dot_product(v0, ijk.v[2]);
    return result;
}
 
 
OOINLINE bool OOTriangleIsDegenerate(Triangle tri)
{
    return vector_equal(tri.v[0], tri.v[1]) ||
           vector_equal(tri.v[1], tri.v[2]) ||
           vector_equal(tri.v[2], tri.v[0]);
}
 
 
#endif  /* INCLUDED_OOMATHS_h */