void Chains::BreakableJointPostSolve(cpConstraint *joint, cpSpace *space) { cpFloat dt = cpSpaceGetCurrentTimeStep(space); // Convert the impulse to a force by dividing it by the timestep. cpFloat force = cpConstraintGetImpulse(joint)/dt; cpFloat maxForce = cpConstraintGetMaxForce(joint); // If the force is almost as big as the joint's max force, break it. if(force > 0.9*maxForce){ cpSpaceAddPostStepCallback(space, (cpPostStepFunc)BreakablejointPostStepRemove, joint, NULL); } }
int modcpSpaceGetCurrentTimeStep(INSTANCE * my, int * params){ float r=cpSpaceGetCurrentTimeStep(cpEspacio); return *(int*)&r; }
cpFloat Space::getCurrentTimeStep(void) { return cpSpaceGetCurrentTimeStep(space); }
cpBool Buoyancy::WaterPreSolve(cpArbiter *arb, cpSpace *space, void *ptr) { CP_ARBITER_GET_SHAPES(arb, water, poly); cpBody *body = cpShapeGetBody(poly); // Get the top of the water sensor bounding box to use as the water level. cpFloat level = cpShapeGetBB(water).t; // Clip the polygon against the water level int count = cpPolyShapeGetCount(poly); int clippedCount = 0; #ifdef _MSC_VER // MSVC is pretty much the only compiler in existence that doesn't support variable sized arrays. cpVect clipped[10]; #else cpVect clipped[count + 1]; #endif for(int i=0, j=count-1; i<count; j=i, i++){ cpVect a = cpBodyLocalToWorld(body, cpPolyShapeGetVert(poly, j)); cpVect b = cpBodyLocalToWorld(body, cpPolyShapeGetVert(poly, i)); if(a.y < level){ clipped[clippedCount] = a; clippedCount++; } cpFloat a_level = a.y - level; cpFloat b_level = b.y - level; if(a_level*b_level < 0.0f){ cpFloat t = cpfabs(a_level)/(cpfabs(a_level) + cpfabs(b_level)); clipped[clippedCount] = cpvlerp(a, b, t); clippedCount++; } } // Calculate buoyancy from the clipped polygon area cpFloat clippedArea = cpAreaForPoly(clippedCount, clipped, 0.0f); cpFloat displacedMass = clippedArea*FLUID_DENSITY; cpVect centroid = cpCentroidForPoly(clippedCount, clipped); cpDataPointer data = ptr; DrawPolygon(clippedCount, clipped, 0.0f, RGBAColor(0, 0, 1, 1), RGBAColor(0, 0, 1, 0.1f), data); DrawDot(5, centroid, RGBAColor(0, 0, 1, 1), data); cpFloat dt = cpSpaceGetCurrentTimeStep(space); cpVect g = cpSpaceGetGravity(space); // Apply the buoyancy force as an impulse. cpBodyApplyImpulseAtWorldPoint(body, cpvmult(g, -displacedMass*dt), centroid); // Apply linear damping for the fluid drag. cpVect v_centroid = cpBodyGetVelocityAtWorldPoint(body, centroid); cpFloat k = k_scalar_body(body, centroid, cpvnormalize(v_centroid)); cpFloat damping = clippedArea*FLUID_DRAG*FLUID_DENSITY; cpFloat v_coef = cpfexp(-damping*dt*k); // linear drag // cpFloat v_coef = 1.0/(1.0 + damping*dt*cpvlength(v_centroid)*k); // quadratic drag cpBodyApplyImpulseAtWorldPoint(body, cpvmult(cpvsub(cpvmult(v_centroid, v_coef), v_centroid), 1.0/k), centroid); // Apply angular damping for the fluid drag. cpVect cog = cpBodyLocalToWorld(body, cpBodyGetCenterOfGravity(body)); cpFloat w_damping = cpMomentForPoly(FLUID_DRAG*FLUID_DENSITY*clippedArea, clippedCount, clipped, cpvneg(cog), 0.0f); cpBodySetAngularVelocity(body, cpBodyGetAngularVelocity(body)*cpfexp(-w_damping*dt/cpBodyGetMoment(body))); return cpTrue; }