mirror of https://github.com/axmolengine/axmol.git
127 lines
4.0 KiB
C
127 lines
4.0 KiB
C
/* Copyright (c) 2007 Scott Lembcke
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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// These are utility routines to use when creating custom constraints.
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// I'm not sure if this should be part of the private API or not.
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// I should probably clean up the naming conventions if it is...
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#define CP_DefineClassGetter(t) const cpConstraintClass * t##GetClass(void){return (cpConstraintClass *)&klass;}
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void cpConstraintInit(cpConstraint *constraint, const cpConstraintClass *klass, cpBody *a, cpBody *b);
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static inline cpVect
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relative_velocity(cpBody *a, cpBody *b, cpVect r1, cpVect r2){
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cpVect v1_sum = cpvadd(a->v, cpvmult(cpvperp(r1), a->w));
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cpVect v2_sum = cpvadd(b->v, cpvmult(cpvperp(r2), b->w));
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return cpvsub(v2_sum, v1_sum);
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}
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static inline cpFloat
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normal_relative_velocity(cpBody *a, cpBody *b, cpVect r1, cpVect r2, cpVect n){
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return cpvdot(relative_velocity(a, b, r1, r2), n);
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}
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static inline void
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apply_impulse(cpBody *body, cpVect j, cpVect r){
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body->v = cpvadd(body->v, cpvmult(j, body->m_inv));
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body->w += body->i_inv*cpvcross(r, j);
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}
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static inline void
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apply_impulses(cpBody *a , cpBody *b, cpVect r1, cpVect r2, cpVect j)
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{
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apply_impulse(a, cpvneg(j), r1);
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apply_impulse(b, j, r2);
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}
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static inline void
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apply_bias_impulse(cpBody *body, cpVect j, cpVect r)
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{
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body->CP_PRIVATE(v_bias) = cpvadd(body->CP_PRIVATE(v_bias), cpvmult(j, body->m_inv));
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body->CP_PRIVATE(w_bias) += body->i_inv*cpvcross(r, j);
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}
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static inline void
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apply_bias_impulses(cpBody *a , cpBody *b, cpVect r1, cpVect r2, cpVect j)
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{
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apply_bias_impulse(a, cpvneg(j), r1);
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apply_bias_impulse(b, j, r2);
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}
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static inline cpFloat
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k_scalar_body(cpBody *body, cpVect r, cpVect n)
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{
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cpFloat rcn = cpvcross(r, n);
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return body->m_inv + body->i_inv*rcn*rcn;
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}
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static inline cpFloat
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k_scalar(cpBody *a, cpBody *b, cpVect r1, cpVect r2, cpVect n)
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{
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cpFloat value = k_scalar_body(a, r1, n) + k_scalar_body(b, r2, n);
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cpAssertSoft(value != 0.0, "Unsolvable collision or constraint.");
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return value;
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}
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static inline cpMat2x2
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k_tensor(cpBody *a, cpBody *b, cpVect r1, cpVect r2)
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{
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cpFloat m_sum = a->m_inv + b->m_inv;
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// start with Identity*m_sum
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cpFloat k11 = m_sum, k12 = 0.0f;
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cpFloat k21 = 0.0f, k22 = m_sum;
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// add the influence from r1
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cpFloat a_i_inv = a->i_inv;
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cpFloat r1xsq = r1.x * r1.x * a_i_inv;
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cpFloat r1ysq = r1.y * r1.y * a_i_inv;
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cpFloat r1nxy = -r1.x * r1.y * a_i_inv;
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k11 += r1ysq; k12 += r1nxy;
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k21 += r1nxy; k22 += r1xsq;
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// add the influnce from r2
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cpFloat b_i_inv = b->i_inv;
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cpFloat r2xsq = r2.x * r2.x * b_i_inv;
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cpFloat r2ysq = r2.y * r2.y * b_i_inv;
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cpFloat r2nxy = -r2.x * r2.y * b_i_inv;
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k11 += r2ysq; k12 += r2nxy;
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k21 += r2nxy; k22 += r2xsq;
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// invert
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cpFloat det = k11*k22 - k12*k21;
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cpAssertSoft(det != 0.0, "Unsolvable constraint.");
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cpFloat det_inv = 1.0f/det;
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return cpMat2x2New(
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k22*det_inv, -k12*det_inv,
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-k21*det_inv, k11*det_inv
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);
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}
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static inline cpFloat
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bias_coef(cpFloat errorBias, cpFloat dt)
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{
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return 1.0f - cpfpow(errorBias, dt);
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}
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