171 lines
No EOL
11 KiB
Text
171 lines
No EOL
11 KiB
Text
/**********************************************************************************************
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*
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* Physac v1.1 - 2D Physics library for videogames
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*
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* DESCRIPTION:
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*
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* Physac is a small 2D physics library written in pure C. The engine uses a fixed time-step thread loop
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* to simluate physics. A physics step contains the following phases: get collision information,
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* apply dynamics, collision solving and position correction. It uses a very simple struct for physic
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* bodies with a position vector to be used in any 3D rendering API.
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*
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* CONFIGURATION:
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*
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* #define PHYSAC_IMPLEMENTATION
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* Generates the implementation of the library into the included file.
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* If not defined, the library is in header only mode and can be included in other headers
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* or source files without problems. But only ONE file should hold the implementation.
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*
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* #define PHYSAC_STATIC (defined by default)
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* The generated implementation will stay private inside implementation file and all
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* internal symbols and functions will only be visible inside that file.
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*
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* #define PHYSAC_NO_THREADS
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* The generated implementation won't include pthread library and user must create a secondary thread to call PhysicsThread().
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* It is so important that the thread where PhysicsThread() is called must not have v-sync or any other CPU limitation.
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*
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* #define PHYSAC_STANDALONE
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* Avoid raylib.h header inclusion in this file. Data types defined on raylib are defined
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* internally in the library and input management and drawing functions must be provided by
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* the user (check library implementation for further details).
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*
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* #define PHYSAC_DEBUG
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* Traces log messages when creating and destroying physics bodies and detects errors in physics
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* calculations and reference exceptions; it is useful for debug purposes
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*
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* #define PHYSAC_MALLOC()
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* #define PHYSAC_FREE()
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* You can define your own malloc/free implementation replacing stdlib.h malloc()/free() functions.
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* Otherwise it will include stdlib.h and use the C standard library malloc()/free() function.
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*
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*
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* NOTE 1: Physac requires multi-threading, when InitPhysics() a second thread is created to manage physics calculations.
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* NOTE 2: Physac requires static C library linkage to avoid dependency on MinGW DLL (-static -lpthread)
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*
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* Use the following code to compile:
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* gcc -o $(NAME_PART).exe $(FILE_NAME) -s -static -lraylib -lpthread -lopengl32 -lgdi32 -lwinmm -std=c99
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*
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* VERY THANKS TO:
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* - raysan5: helped with library design
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* - ficoos: added support for Linux
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* - R8D8: added support for Linux
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* - jubalh: fixed implementation of time calculations
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* - a3f: fixed implementation of time calculations
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* - define-private-public: added support for OSX
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* - pamarcos: fixed implementation of physics steps
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* - noshbar: fixed some memory leaks
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*
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*
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* LICENSE: zlib/libpng
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*
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* Copyright (c) 2016-2025 Victor Fisac (github: @victorfisac)
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*
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* This software is provided "as-is", without any express or implied warranty. In no event
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* will the authors be held liable for any damages arising from the use of this software.
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*
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* Permission is granted to anyone to use this software for any purpose, including commercial
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* applications, and to alter it and redistribute it freely, subject to the following restrictions:
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*
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* 1. The origin of this software must not be misrepresented; you must not claim that you
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* wrote the original software. If you use this software in a product, an acknowledgment
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* in the product documentation would be appreciated but is not required.
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*
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* 2. Altered source versions must be plainly marked as such, and must not be misrepresented
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* as being the original software.
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*
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* 3. This notice may not be removed or altered from any source distribution.
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*
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**********************************************************************************************/
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// #define PHYSAC_STATIC
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// #define PHYSAC_NO_THREADS
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// #define PHYSAC_STANDALONE
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// #define PHYSAC_DEBUG
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//----------------------------------------------------------------------------------
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// Defines and Macros
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//----------------------------------------------------------------------------------
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//----------------------------------------------------------------------------------
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// Types and Structures Definition
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// NOTE: Below types are required for PHYSAC_STANDALONE usage
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//----------------------------------------------------------------------------------
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typedef enum PhysicsShapeType { PHYSICS_CIRCLE, PHYSICS_POLYGON } PhysicsShapeType;
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// Previously defined to be used in PhysicsShape struct as circular dependencies
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typedef struct PhysicsBodyData *PhysicsBody;
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// Mat2 type (used for polygon shape rotation matrix)
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typedef struct Mat2 {
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float m00;
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float m01;
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float m10;
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float m11;
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} Mat2;
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typedef struct PolygonData {
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unsigned int vertexCount; // Current used vertex and normals count
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Vector2 positions[24]; // Polygon vertex positions vectors
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Vector2 normals[24]; // Polygon vertex normals vectors
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} PolygonData;
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typedef struct PhysicsShape {
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PhysicsShapeType type; // Physics shape type (circle or polygon)
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PhysicsBody body; // Shape physics body reference
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float radius; // Circle shape radius (used for circle shapes)
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Mat2 transform; // Vertices transform matrix 2x2
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PolygonData vertexData; // Polygon shape vertices position and normals data (just used for polygon shapes)
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} PhysicsShape;
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typedef struct PhysicsBodyData {
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unsigned int id; // Reference unique identifier
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bool enabled; // Enabled dynamics state (collisions are calculated anyway)
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Vector2 position; // Physics body shape pivot
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Vector2 velocity; // Current linear velocity applied to position
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Vector2 force; // Current linear force (reset to 0 every step)
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float angularVelocity; // Current angular velocity applied to orient
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float torque; // Current angular force (reset to 0 every step)
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float orient; // Rotation in radians
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float inertia; // Moment of inertia
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float inverseInertia; // Inverse value of inertia
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float mass; // Physics body mass
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float inverseMass; // Inverse value of mass
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float staticFriction; // Friction when the body has not movement (0 to 1)
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float dynamicFriction; // Friction when the body has movement (0 to 1)
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float restitution; // Restitution coefficient of the body (0 to 1)
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bool useGravity; // Apply gravity force to dynamics
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bool isGrounded; // Physics grounded on other body state
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bool freezeOrient; // Physics rotation constraint
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PhysicsShape shape; // Physics body shape information (type, radius, vertices, normals)
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} PhysicsBodyData;
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typedef struct PhysicsManifoldData {
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unsigned int id; // Reference unique identifier
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PhysicsBody bodyA; // Manifold first physics body reference
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PhysicsBody bodyB; // Manifold second physics body reference
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float penetration; // Depth of penetration from collision
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Vector2 normal; // Normal direction vector from 'a' to 'b'
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Vector2 contacts[2]; // Points of contact during collision
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unsigned int contactsCount; // Current collision number of contacts
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float restitution; // Mixed restitution during collision
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float dynamicFriction; // Mixed dynamic friction during collision
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float staticFriction; // Mixed static friction during collision
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} PhysicsManifoldData, *PhysicsManifold;
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//----------------------------------------------------------------------------------
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// Module Functions Declaration
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//----------------------------------------------------------------------------------
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extern /* Functions visible from other files*/ void InitPhysics(void); // Initializes physics values, pointers and creates physics loop thread
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extern /* Functions visible from other files*/ void RunPhysicsStep(void); // Run physics step, to be used if PHYSICS_NO_THREADS is set in your main loop
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extern /* Functions visible from other files*/ void SetPhysicsTimeStep(double delta); // Sets physics fixed time step in milliseconds. 1.666666 by default
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extern /* Functions visible from other files*/ bool IsPhysicsEnabled(void); // Returns true if physics thread is currently enabled
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extern /* Functions visible from other files*/ void SetPhysicsGravity(float x, float y); // Sets physics global gravity force
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extern /* Functions visible from other files*/ PhysicsBody CreatePhysicsBodyCircle(Vector2 pos, float radius, float density); // Creates a new circle physics body with generic parameters
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extern /* Functions visible from other files*/ PhysicsBody CreatePhysicsBodyRectangle(Vector2 pos, float width, float height, float density); // Creates a new rectangle physics body with generic parameters
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extern /* Functions visible from other files*/ PhysicsBody CreatePhysicsBodyPolygon(Vector2 pos, float radius, int sides, float density); // Creates a new polygon physics body with generic parameters
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extern /* Functions visible from other files*/ void PhysicsAddForce(PhysicsBody body, Vector2 force); // Adds a force to a physics body
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extern /* Functions visible from other files*/ void PhysicsAddTorque(PhysicsBody body, float amount); // Adds an angular force to a physics body
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extern /* Functions visible from other files*/ void PhysicsShatter(PhysicsBody body, Vector2 position, float force); // Shatters a polygon shape physics body to little physics bodies with explosion force
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extern /* Functions visible from other files*/ int GetPhysicsBodiesCount(void); // Returns the current amount of created physics bodies
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extern /* Functions visible from other files*/ PhysicsBody GetPhysicsBody(int index); // Returns a physics body of the bodies pool at a specific index
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extern /* Functions visible from other files*/ int GetPhysicsShapeType(int index); // Returns the physics body shape type (PHYSICS_CIRCLE or PHYSICS_POLYGON)
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extern /* Functions visible from other files*/ int GetPhysicsShapeVerticesCount(int index); // Returns the amount of vertices of a physics body shape
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extern /* Functions visible from other files*/ Vector2 GetPhysicsShapeVertex(PhysicsBody body, int vertex); // Returns transformed position of a body shape (body position + vertex transformed position)
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extern /* Functions visible from other files*/ void SetPhysicsBodyRotation(PhysicsBody body, float radians); // Sets physics body shape transform based on radians parameter
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extern /* Functions visible from other files*/ void DestroyPhysicsBody(PhysicsBody body); // Unitializes and destroy a physics body
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extern /* Functions visible from other files*/ void ClosePhysics(void); // Unitializes physics pointers and closes physics loop thread
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/***********************************************************************************
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*
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* PHYSAC IMPLEMENTATION
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*
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************************************************************************************/ |