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/* Copyright (c) 2007 Scott Lembcke
*
* 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.
*/
#include <stdlib.h>
#include <math.h>
#include <float.h>
#include "chipmunk.h"
cpBody*
cpBodyAlloc(void)
{
return (cpBody *)malloc(sizeof(cpBody));
}
cpBody*
cpBodyInit(cpBody *body, cpFloat m, cpFloat i)
{
cpBodySetMass(body, m);
cpBodySetMoment(body, i);
body->p = cpvzero;
body->v = cpvzero;
body->f = cpvzero;
cpBodySetAngle(body, 0.0f);
body->w = 0.0f;
body->t = 0.0f;
body->v_bias = cpvzero;
body->w_bias = 0.0f;
// body->active = 1;
return body;
}
cpBody*
cpBodyNew(cpFloat m, cpFloat i)
{
return cpBodyInit(cpBodyAlloc(), m, i);
}
void cpBodyDestroy(cpBody *body){}
void
cpBodyFree(cpBody *body)
{
if(body) cpBodyDestroy(body);
free(body);
}
void
cpBodySetMass(cpBody *body, cpFloat m)
{
body->m = m;
body->m_inv = 1.0f/m;
}
void
cpBodySetMoment(cpBody *body, cpFloat i)
{
body->i = i;
body->i_inv = 1.0f/i;
}
void
cpBodySetAngle(cpBody *body, cpFloat a)
{
body->a = fmod(a, (cpFloat)M_PI*2.0f);
body->rot = cpvforangle(a);
}
void
cpBodySlew(cpBody *body, cpVect pos, cpFloat dt)
{
cpVect delta = cpvsub(body->p, pos);
body->v = cpvmult(delta, 1.0/dt);
}
void
cpBodyUpdateVelocity(cpBody *body, cpVect gravity, cpFloat damping, cpFloat dt)
{
body->v = cpvadd(cpvmult(body->v, damping), cpvmult(cpvadd(gravity, cpvmult(body->f, body->m_inv)), dt));
body->w = body->w*damping + body->t*body->i_inv*dt;
}
void
cpBodyUpdatePosition(cpBody *body, cpFloat dt)
{
body->p = cpvadd(body->p, cpvmult(cpvadd(body->v, body->v_bias), dt));
cpBodySetAngle(body, body->a + (body->w + body->w_bias)*dt);
body->v_bias = cpvzero;
body->w_bias = 0.0f;
}
void
cpBodyResetForces(cpBody *body)
{
body->f = cpvzero;
body->t = 0.0f;
}
void
cpBodyApplyForce(cpBody *body, cpVect f, cpVect r)
{
body->f = cpvadd(body->f, f);
body->t += cpvcross(r, f);
}
void
cpDampedSpring(cpBody *a, cpBody *b, cpVect anchr1, cpVect anchr2, cpFloat rlen, cpFloat k, cpFloat dmp, cpFloat dt)
{
// Calculate the world space anchor coordinates.
cpVect r1 = cpvrotate(anchr1, a->rot);
cpVect r2 = cpvrotate(anchr2, b->rot);
cpVect delta = cpvsub(cpvadd(b->p, r2), cpvadd(a->p, r1));
cpFloat dist = cpvlength(delta);
cpVect n = dist ? cpvmult(delta, 1.0f/dist) : cpvzero;
cpFloat f_spring = (dist - rlen)*k;
// Calculate the world relative velocities of the anchor points.
cpVect v1 = cpvadd(a->v, cpvmult(cpvperp(r1), a->w));
cpVect v2 = cpvadd(b->v, cpvmult(cpvperp(r2), b->w));
// Calculate the damping force.
// This really should be in the impulse solver and can produce problems when using large damping values.
cpFloat vrn = cpvdot(cpvsub(v2, v1), n);
cpFloat f_damp = vrn*cpfmin(dmp, 1.0f/(dt*(a->m_inv + b->m_inv)));
// Apply!
cpVect f = cpvmult(n, f_spring + f_damp);
cpBodyApplyForce(a, f, r1);
cpBodyApplyForce(b, cpvneg(f), r2);
}
//int
//cpBodyMarkLowEnergy(cpBody *body, cpFloat dvsq, int max)
//{
// cpFloat ke = body->m*cpvdot(body->v, body->v);
// cpFloat re = body->i*body->w*body->w;
//
// if(ke + re > body->m*dvsq)
// body->active = 1;
// else if(body->active)
// body->active = (body->active + 1)%(max + 1);
// else {
// body->v = cpvzero;
// body->v_bias = cpvzero;
// body->w = 0.0f;
// body->w_bias = 0.0f;
// }
//
// return body->active;
//}
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