OOVector.m

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/*
 
OOVector.m
 
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.
 
*/
 
#include "OOMaths.h"
 
 
const Vector            kZeroVector = { 0.0f, 0.0f, 0.0f };
const Vector            kBasisXVector = { 1.0f, 0.0f, 0.0f };
const Vector            kBasisYVector = { 0.0f, 1.0f, 0.0f };
const Vector            kBasisZVector = { 0.0f, 0.0f, 1.0f };
 
const Vector2D          kZeroVector2D = { 0.0f, 0.0f };
const Vector2D          kBasisXVector2D = { 1.0f, 0.0f };
const Vector2D          kBasisYVector2D = { 0.0f, 1.0f };
 
#if !OOMATHS_STANDALONE
const BoundingBox       kZeroBoundingBox = {{ 0.0f, 0.0f, 0.0f }, { 0.0f, 0.0f, 0.0f }};
#endif
 
 
#if __OBJC__
NSString *VectorDescription(Vector vector)
{
    return [NSString stringWithFormat:@"(%g, %g, %g)", vector.x, vector.y, vector.z];
}
 
@implementation OONativeVector
 
- (id) initWithVector:(Vector)vect
{
    self = [super init];
    if (EXPECT_NOT(self == nil))  return nil;
 
    v = vect;
 
    return self;
}
 
- (Vector) getVector
{
    return v;
}
 
 
@end
 
#endif
 
 
 
#if !OOMATHS_STANDALONE
/*  This generates random vectors distrubuted evenly over the surface of the
    unit sphere. It does this the simple way, by generating vectors in the
    half-unit cube and rejecting those outside the half-unit sphere (and the
    zero vector), then normalizing the result. (Half-unit measures are used
    to avoid unnecessary multiplications of randf() values.)
    
    In principle, using three normally-distributed co-ordinates (and again
    normalizing the result) would provide the right result without looping, but
    I don't trust bellf() so I'll go with the simple approach for now.
*/
Vector OORandomUnitVector(void)
{
    Vector              v;
    float               m;
    
    do
    {
        v = make_vector(randf() - 0.5f, randf() - 0.5f, randf() - 0.5f);
        m = magnitude2(v);
    }
    while (m > 0.25f || m == 0.0f); // We're confining to a sphere of radius 0.5 using the sqared magnitude; 0.5 squared is 0.25.
    
    return vector_normal(v);
}
 
 
Vector OOVectorRandomSpatial(OOScalar maxLength)
{
    Vector              v;
    float               m;
    
    do
    {
        v = make_vector(randf() - 0.5f, randf() - 0.5f, randf() - 0.5f);
        m = magnitude2(v);
    }
    while (m > 0.25f);  // We're confining to a sphere of radius 0.5 using the sqared magnitude; 0.5 squared is 0.25.
    
    return vector_multiply_scalar(v, maxLength * 2.0f); // 2.0 is to compensate for the 0.5-radius sphere.
}
 
 
Vector OOVectorRandomRadial(OOScalar maxLength)
{
    return vector_multiply_scalar(OORandomUnitVector(), randf() * maxLength);
}
 
 
Vector OORandomPositionInBoundingBox(BoundingBox bb)
{
    Vector result;
    result.x = bb.min.x + randf() * (bb.max.x - bb.min.x);
    result.y = bb.min.y + randf() * (bb.max.y - bb.min.y);
    result.z = bb.min.z + randf() * (bb.max.z - bb.min.z);
    return result;
}
 
// only need high precision versions of these
/*Vector OORandomPositionInCylinder(Vector centre1, OOScalar exclusion1, Vector centre2, OOScalar exclusion2, OOScalar radius)
{
    OOScalar exc12 = exclusion1*exclusion1;
    OOScalar exc22 = exclusion2*exclusion2;
    Vector result;
    do
    {
        result = vector_add(OOVectorInterpolate(centre1,centre2,randf()),OOVectorRandomSpatial(radius));
    }
    while(distance2(result,centre1)<exc12 || distance2(result,centre2)<exc22);
    return result;
}
 
Vector OORandomPositionInShell(Vector centre, OOScalar inner, OOScalar outer)
{
    Vector result;
    OOScalar inner2 = inner*inner;
    do
    {
        result = vector_add(centre,OOVectorRandomSpatial(outer));
    } while(distance2(result,centre)<inner2);
    return result;
    }*/
 
#endif