chipmunk_structs.h

/* Copyright (c) 2025 Victor Blomqvist
 * Copyright (c) 2007-2024 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.
*/
 
// All of the struct definitions for Chipmunk should be considered part of the private API.
// However, it is very valuable to know the struct sizes for preallocating memory.
 
#ifndef CHIPMUNK_STRUCTS_H
#define CHIPMUNK_STRUCTS_H
 
#include "chipmunk/chipmunk.h"
 
struct cpArray {
  int num, max;
  void **arr;
};
 
struct cpBody {
  // Integration functions
  cpBodyVelocityFunc velocity_func;
  cpBodyPositionFunc position_func;
  
  // mass and it's inverse
  cpFloat m;
  cpFloat m_inv;
  
  // moment of inertia and it's inverse
  cpFloat i;
  cpFloat i_inv;
  
  // center of gravity
  cpVect cog;
  
  // position, velocity, force
  cpVect p;
  cpVect v;
  cpVect f;
  
  // Angle, angular velocity, torque (radians)
  cpFloat a;
  cpFloat w;
  cpFloat t;
  
  cpTransform transform;
  
  cpDataPointer userData;
  
  // "pseudo-velocities" used for eliminating overlap.
  // Erin Catto has some papers that talk about what these are.
  cpVect v_bias;
  cpFloat w_bias;
  
  cpSpace *space;
  
  cpShape *shapeList;
  cpArbiter *arbiterList;
  cpConstraint *constraintList;
  
  struct {
    cpBody *root;
    cpBody *next;
    cpFloat idleTime;
  } sleeping;
};
 
enum cpArbiterState {
  // Arbiter is active and its the first collision.
  CP_ARBITER_STATE_FIRST_COLLISION,
  // Arbiter is active and its not the first collision.
  CP_ARBITER_STATE_NORMAL,
  // Collision has been explicitly ignored.
  CP_ARBITER_STATE_IGNORE,
  // Collison is no longer active. A space will cache an arbiter for up to cpSpace.collisionPersistence more steps.
  CP_ARBITER_STATE_CACHED,
  // Collison arbiter is invalid because one of the shapes was removed.
  CP_ARBITER_STATE_INVALIDATED,
};
 
struct cpArbiterThread {
  struct cpArbiter *next, *prev;
};
 
struct cpContact {
  cpVect r1, r2;
  
  cpFloat nMass, tMass;
  cpFloat bounce; // TODO: look for an alternate bounce solution.
 
  cpFloat jnAcc, jtAcc, jBias;
  cpFloat bias;
  
  cpHashValue hash;
};
 
struct cpCollisionInfo {
  const cpShape *a, *b;
  cpCollisionID id;
  
  cpVect n;
  
  int count;
  // TODO Should this be a unique struct type?
  struct cpContact *arr;
};
 
struct cpArbiter {
  cpFloat e;
  cpFloat u;
  cpVect surface_vr;
  
  cpDataPointer data;
  
  const cpShape *a, *b;
  cpBody *body_a, *body_b;
  struct cpArbiterThread thread_a, thread_b;
  
  int count;
  struct cpContact *contacts;
  cpVect n;
  
  // CollisionHandlers.
  cpCollisionHandler *handlerAB, *handlerBA, *handlerA, *handlerB;
  cpBool swapped;
  
  cpTimestamp stamp;
  enum cpArbiterState state;
  cpBool processCollision;
};
 
struct cpShapeMassInfo {
  cpFloat m;
  cpFloat i;
  cpVect cog;
  cpFloat area;
};
 
typedef enum cpShapeType{
  CP_CIRCLE_SHAPE,
  CP_SEGMENT_SHAPE,
  CP_POLY_SHAPE,
  CP_NUM_SHAPES
} cpShapeType;
 
typedef cpBB (*cpShapeCacheDataImpl)(cpShape *shape, cpTransform transform);
typedef void (*cpShapeDestroyImpl)(cpShape *shape);
typedef void (*cpShapePointQueryImpl)(const cpShape *shape, cpVect p, cpPointQueryInfo *info);
typedef void (*cpShapeSegmentQueryImpl)(const cpShape *shape, cpVect a, cpVect b, cpFloat radius, cpSegmentQueryInfo *info);
 
typedef struct cpShapeClass cpShapeClass;
 
struct cpShapeClass {
  cpShapeType type;
  
  cpShapeCacheDataImpl cacheData;
  cpShapeDestroyImpl destroy;
  cpShapePointQueryImpl pointQuery;
  cpShapeSegmentQueryImpl segmentQuery;
};
 
struct cpShape {
  const cpShapeClass *klass;
  
  cpSpace *space;
  cpBody *body;
  struct cpShapeMassInfo massInfo;
  cpBB bb;
  
  cpBool sensor;
  
  cpFloat e;
  cpFloat u;
  cpVect surfaceV;
 
  cpDataPointer userData;
  
  cpCollisionType type;
  cpShapeFilter filter;
  
  cpShape *next;
  cpShape *prev;
  
  cpHashValue hashid;
};
 
struct cpCircleShape {
  cpShape shape;
  
  cpVect c, tc;
  cpFloat r;
};
 
struct cpSegmentShape {
  cpShape shape;
  
  cpVect a, b, n;
  cpVect ta, tb, tn;
  cpFloat r;
  
  cpVect a_tangent, b_tangent;
};
 
struct cpSplittingPlane {
  cpVect v0, n;
};
 
#define CP_POLY_SHAPE_INLINE_ALLOC 6
 
struct cpPolyShape {
  cpShape shape;
  
  cpFloat r;
  
  int count;
  // The untransformed planes are appended at the end of the transformed planes.
  struct cpSplittingPlane *planes;
  
  // Allocate a small number of splitting planes internally for simple poly.
  struct cpSplittingPlane _planes[2*CP_POLY_SHAPE_INLINE_ALLOC];
};
 
typedef void (*cpConstraintPreStepImpl)(cpConstraint *constraint, cpFloat dt);
typedef void (*cpConstraintApplyCachedImpulseImpl)(cpConstraint *constraint, cpFloat dt_coef);
typedef void (*cpConstraintApplyImpulseImpl)(cpConstraint *constraint, cpFloat dt);
typedef cpFloat (*cpConstraintGetImpulseImpl)(cpConstraint *constraint);
 
typedef struct cpConstraintClass {
  cpConstraintPreStepImpl preStep;
  cpConstraintApplyCachedImpulseImpl applyCachedImpulse;
  cpConstraintApplyImpulseImpl applyImpulse;
  cpConstraintGetImpulseImpl getImpulse;
} cpConstraintClass;
 
struct cpConstraint {
  const cpConstraintClass *klass;
  
  cpSpace *space;
  
  cpBody *a, *b;
  cpConstraint *next_a, *next_b;
  
  cpFloat maxForce;
  cpFloat errorBias;
  cpFloat maxBias;
  
  cpBool collideBodies;
  
  cpConstraintPreSolveFunc preSolve;
  cpConstraintPostSolveFunc postSolve;
  
  cpDataPointer userData;
};
 
struct cpPinJoint {
  cpConstraint constraint;
  cpVect anchorA, anchorB;
  cpFloat dist;
  
  cpVect r1, r2;
  cpVect n;
  cpFloat nMass;
  
  cpFloat jnAcc;
  cpFloat bias;
};
 
struct cpSlideJoint {
  cpConstraint constraint;
  cpVect anchorA, anchorB;
  cpFloat min, max;
  
  cpVect r1, r2;
  cpVect n;
  cpFloat nMass;
  
  cpFloat jnAcc;
  cpFloat bias;
};
 
struct cpPivotJoint {
  cpConstraint constraint;
  cpVect anchorA, anchorB;
  
  cpVect r1, r2;
  cpMat2x2 k;
  
  cpVect jAcc;
  cpVect bias;
};
 
struct cpGrooveJoint {
  cpConstraint constraint;
  cpVect grv_n, grv_a, grv_b;
  cpVect  anchorB;
  
  cpVect grv_tn;
  cpFloat clamp;
  cpVect r1, r2;
  cpMat2x2 k;
  
  cpVect jAcc;
  cpVect bias;
};
 
struct cpDampedSpring {
  cpConstraint constraint;
  cpVect anchorA, anchorB;
  cpFloat restLength;
  cpFloat stiffness;
  cpFloat damping;
  cpDampedSpringForceFunc springForceFunc;
  
  cpFloat target_vrn;
  cpFloat v_coef;
  
  cpVect r1, r2;
  cpFloat nMass;
  cpVect n;
  
  cpFloat jAcc;
};
 
struct cpDampedRotarySpring {
  cpConstraint constraint;
  cpFloat restAngle;
  cpFloat stiffness;
  cpFloat damping;
  cpDampedRotarySpringTorqueFunc springTorqueFunc;
  
  cpFloat target_wrn;
  cpFloat w_coef;
  
  cpFloat iSum;
  cpFloat jAcc;
};
 
struct cpRotaryLimitJoint {
  cpConstraint constraint;
  cpFloat min, max;
  
  cpFloat iSum;
    
  cpFloat bias;
  cpFloat jAcc;
};
 
struct cpRatchetJoint {
  cpConstraint constraint;
  cpFloat angle, phase, ratchet;
  
  cpFloat iSum;
    
  cpFloat bias;
  cpFloat jAcc;
};
 
struct cpGearJoint {
  cpConstraint constraint;
  cpFloat phase, ratio;
  cpFloat ratio_inv;
  
  cpFloat iSum;
    
  cpFloat bias;
  cpFloat jAcc;
};
 
struct cpSimpleMotor {
  cpConstraint constraint;
  cpFloat rate;
  
  cpFloat iSum;
    
  cpFloat jAcc;
};
 
typedef struct cpContactBufferHeader cpContactBufferHeader;
typedef void (*cpSpaceArbiterApplyImpulseFunc)(cpArbiter *arb);
 
struct cpSpace {
  int iterations;
  
  cpVect gravity;
  cpFloat damping;
  
  cpFloat idleSpeedThreshold;
  cpFloat sleepTimeThreshold;
  
  cpFloat collisionSlop;
  cpFloat collisionBias;
  cpTimestamp collisionPersistence;
  
  cpDataPointer userData;
  
  cpTimestamp stamp;
  cpFloat curr_dt;
 
  cpArray *dynamicBodies;
  cpArray *staticBodies;
  cpArray *rousedBodies;
  cpArray *sleepingComponents;
  
  cpHashValue shapeIDCounter;
  cpSpatialIndex *staticShapes;
  cpSpatialIndex *dynamicShapes;
  
  cpArray *constraints;
  
  cpArray *arbiters;
  cpContactBufferHeader *contactBuffersHead;
  cpHashSet *cachedArbiters;
  cpArray *pooledArbiters;
  
  cpArray *allocatedBuffers;
  int locked;
  
  cpHashSet *collisionHandlers;
  cpCollisionHandler globalHandler;
  
  cpBool skipPostStep;
  cpArray *postStepCallbacks;
  
  cpBody *staticBody;
  cpBody _staticBody;
};
 
typedef struct cpPostStepCallback {
  cpPostStepFunc func;
  void *key;
  void *data;
} cpPostStepCallback;
 
#endif