cpVect.h

/* Copyright (c) 2013 Scott Lembcke and Howling Moon Software
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#ifndef CHIPMUNK_VECT_H
#define CHIPMUNK_VECT_H

#include "chipmunk_types.h"


static const cpVect cpvzero = {0.0f,0.0f};

static inline cpVect cpv(const cpFloat x, const cpFloat y)
{
  cpVect v = {x, y};
  return v;
}

static inline cpBool cpveql(const cpVect v1, const cpVect v2)
{
  return (v1.x == v2.x && v1.y == v2.y);
}

static inline cpVect cpvadd(const cpVect v1, const cpVect v2)
{
  return cpv(v1.x + v2.x, v1.y + v2.y);
}

static inline cpVect cpvsub(const cpVect v1, const cpVect v2)
{
  return cpv(v1.x - v2.x, v1.y - v2.y);
}

static inline cpVect cpvneg(const cpVect v)
{
  return cpv(-v.x, -v.y);
}

static inline cpVect cpvmult(const cpVect v, const cpFloat s)
{
  return cpv(v.x*s, v.y*s);
}

static inline cpFloat cpvdot(const cpVect v1, const cpVect v2)
{
  return v1.x*v2.x + v1.y*v2.y;
}

static inline cpFloat cpvcross(const cpVect v1, const cpVect v2)
{
  return v1.x*v2.y - v1.y*v2.x;
}

static inline cpVect cpvperp(const cpVect v)
{
  return cpv(-v.y, v.x);
}

static inline cpVect cpvrperp(const cpVect v)
{
  return cpv(v.y, -v.x);
}

static inline cpVect cpvproject(const cpVect v1, const cpVect v2)
{
  return cpvmult(v2, cpvdot(v1, v2)/cpvdot(v2, v2));
}

static inline cpVect cpvforangle(const cpFloat a)
{
  return cpv(cpfcos(a), cpfsin(a));
}

static inline cpFloat cpvtoangle(const cpVect v)
{
  return cpfatan2(v.y, v.x);
}

static inline cpVect cpvrotate(const cpVect v1, const cpVect v2)
{
  return cpv(v1.x*v2.x - v1.y*v2.y, v1.x*v2.y + v1.y*v2.x);
}

static inline cpVect cpvunrotate(const cpVect v1, const cpVect v2)
{
  return cpv(v1.x*v2.x + v1.y*v2.y, v1.y*v2.x - v1.x*v2.y);
}

static inline cpFloat cpvlengthsq(const cpVect v)
{
  return cpvdot(v, v);
}

static inline cpFloat cpvlength(const cpVect v)
{
  return cpfsqrt(cpvdot(v, v));
}

static inline cpVect cpvlerp(const cpVect v1, const cpVect v2, const cpFloat t)
{
  return cpvadd(cpvmult(v1, 1.0f - t), cpvmult(v2, t));
}

static inline cpVect cpvnormalize(const cpVect v)
{
  // Neat trick I saw somewhere to avoid div/0.
  return cpvmult(v, 1.0f/(cpvlength(v) + CPFLOAT_MIN));
}

static inline cpVect
cpvslerp(const cpVect v1, const cpVect v2, const cpFloat t)
{
  cpFloat dot = cpvdot(cpvnormalize(v1), cpvnormalize(v2));
  cpFloat omega = cpfacos(cpfclamp(dot, -1.0f, 1.0f));
  
  if(omega < 1e-3){
    // If the angle between two vectors is very small, lerp instead to avoid precision issues.
    return cpvlerp(v1, v2, t);
  } else {
    cpFloat denom = 1.0f/cpfsin(omega);
    return cpvadd(cpvmult(v1, cpfsin((1.0f - t)*omega)*denom), cpvmult(v2, cpfsin(t*omega)*denom));
  }
}

static inline cpVect
cpvslerpconst(const cpVect v1, const cpVect v2, const cpFloat a)
{
  cpFloat dot = cpvdot(cpvnormalize(v1), cpvnormalize(v2));
  cpFloat omega = cpfacos(cpfclamp(dot, -1.0f, 1.0f));
  
  return cpvslerp(v1, v2, cpfmin(a, omega)/omega);
}

static inline cpVect cpvclamp(const cpVect v, const cpFloat len)
{
  return (cpvdot(v,v) > len*len) ? cpvmult(cpvnormalize(v), len) : v;
}

static inline cpVect cpvlerpconst(cpVect v1, cpVect v2, cpFloat d)
{
  return cpvadd(v1, cpvclamp(cpvsub(v2, v1), d));
}

static inline cpFloat cpvdist(const cpVect v1, const cpVect v2)
{
  return cpvlength(cpvsub(v1, v2));
}

static inline cpFloat cpvdistsq(const cpVect v1, const cpVect v2)
{
  return cpvlengthsq(cpvsub(v1, v2));
}

static inline cpBool cpvnear(const cpVect v1, const cpVect v2, const cpFloat dist)
{
  return cpvdistsq(v1, v2) < dist*dist;
}



// NUKE
static inline cpMat2x2
cpMat2x2New(cpFloat a, cpFloat b, cpFloat c, cpFloat d)
{
  cpMat2x2 m = {a, b, c, d};
  return m;
}

static inline cpVect
cpMat2x2Transform(cpMat2x2 m, cpVect v)
{
  return cpv(v.x*m.a + v.y*m.b, v.x*m.c + v.y*m.d);
}


#endif