Converted physac module to header only

1 files changed, 667 insertions, 17 deletions

diff --git a/src/physac.h b/src/physac.h
index b2ae2766..c8466a12 100644
--- a/src/physac.h
+++ b/src/physac.h
@@ -1,8 +1,45 @@
 /**********************************************************************************************
 *
-*   [physac] raylib physics module - Basic functions to apply physics to 2D objects
+*   physac 1.0 - 2D Physics library for raylib (https://github.com/raysan5/raylib)
 *
-*   Copyright (c) 2016 Victor Fisac and Ramon Santamaria
+*   // TODO: Description...
+* 
+*   CONFIGURATION:
+*   
+*   #define PHYSAC_IMPLEMENTATION
+*       Generates the implementation of the library into the included file.
+*       If not defined, the library is in header only mode and can be included in other headers 
+*       or source files without problems. But only ONE file should hold the implementation.
+*
+*   #define PHYSAC_STATIC (defined by default)
+*       The generated implementation will stay private inside implementation file and all 
+*       internal symbols and functions will only be visible inside that file.
+*
+*   #define PHYSAC_STANDALONE
+*       Avoid raylib.h header inclusion in this file. Data types defined on raylib are defined
+*       internally in the library and input management and drawing functions must be provided by
+*       the user (check library implementation for further details).
+*
+*   #define PHYSAC_MALLOC()
+*   #define PHYSAC_FREE()
+*       You can define your own malloc/free implementation replacing stdlib.h malloc()/free() functions.
+*       Otherwise it will include stdlib.h and use the C standard library malloc()/free() function.
+*       
+*   LIMITATIONS:
+*
+*       // TODO.
+*
+*   VERSIONS:
+*
+*   1.0 (09-Jun-2016) Module names review and converted to header-only.
+*   0.9 (23-Mar-2016) Complete module redesign, steps-based for better physics resolution.
+*   0.3 (13-Feb-2016) Reviewed to add PhysicObjects pool.
+*   0.2 (03-Jan-2016) Improved physics calculations.
+*   0.1 (30-Dec-2015) Initial release.
+*
+*   LICENSE: zlib/libpng
+*
+*   Copyright (c) 2016 Victor Fisac (main developer) and Ramon Santamaria
 *
 *   This software is provided "as-is", without any express or implied warranty. In no event
 *   will the authors be held liable for any damages arising from the use of this software.
@@ -24,6 +61,21 @@
 #ifndef PHYSAC_H
 #define PHYSAC_H
 
+#if !defined(RAYGUI_STANDALONE)
+    #include "raylib.h"
+#endif
+
+#define PHYSAC_STATIC
+#ifdef PHYSAC_STATIC
+    #define PHYSACDEF static            // Functions just visible to module including this file
+#else
+    #ifdef __cplusplus
+        #define PHYSACDEF extern "C"    // Functions visible from other files (no name mangling of functions in C++)
+    #else
+        #define PHYSACDEF extern        // Functions visible from other files
+    #endif
+#endif
+
 //----------------------------------------------------------------------------------
 // Defines and Macros
 //----------------------------------------------------------------------------------
@@ -33,12 +85,28 @@
 // Types and Structures Definition
 // NOTE: Below types are required for PHYSAC_STANDALONE usage
 //----------------------------------------------------------------------------------
+#if defined(PHYSAC_STANDALONE)
+    #ifndef __cplusplus
+    // Boolean type
+        #ifndef true
+            typedef enum { false, true } bool;
+        #endif
+    #endif
 
-// Vector2 type
-typedef struct Vector2 {
-    float x;
-    float y;
-} Vector2;
+    // Vector2 type
+    typedef struct Vector2 {
+        float x;
+        float y;
+    } Vector2;
+
+    // Rectangle type
+    typedef struct Rectangle {
+        int x;
+        int y;
+        int width;
+        int height;
+    } Rectangle;
+#endif
 
 typedef enum { COLLIDER_CIRCLE, COLLIDER_RECTANGLE } ColliderType;
 
@@ -66,13 +134,13 @@ typedef struct Collider {
     int radius;             // Used for COLLIDER_CIRCLE
 } Collider;
 
-typedef struct PhysicObjectData {
+typedef struct PhysicBodyData {
     unsigned int id;
     Transform transform;
     Rigidbody rigidbody;
     Collider collider;
     bool enabled;
-} PhysicObjectData, *PhysicObject;
+} PhysicBodyData, *PhysicBody;
 
 #ifdef __cplusplus
 extern "C" {            // Prevents name mangling of functions
@@ -81,20 +149,602 @@ extern "C" {            // Prevents name mangling of functions
 //----------------------------------------------------------------------------------
 // Module Functions Declaration
 //----------------------------------------------------------------------------------
-void InitPhysics(Vector2 gravity);                                                      // Initializes pointers array (just pointers, fixed size)
-void UpdatePhysics();                                                                   // Update physic objects, calculating physic behaviours and collisions detection
-void ClosePhysics();                                                                    // Unitialize all physic objects and empty the objects pool
+PHYSACDEF void InitPhysics(Vector2 gravity);                                            // Initializes pointers array (just pointers, fixed size)
+PHYSACDEF void UpdatePhysics();                                                         // Update physic objects, calculating physic behaviours and collisions detection
+PHYSACDEF void ClosePhysics();                                                          // Unitialize all physic objects and empty the objects pool
 
-PhysicObject CreatePhysicObject(Vector2 position, float rotation, Vector2 scale);       // Create a new physic object dinamically, initialize it and add to pool
-void DestroyPhysicObject(PhysicObject pObj);                                            // Destroy a specific physic object and take it out of the list
+PHYSACDEF PhysicBody CreatePhysicBody(Vector2 position, float rotation, Vector2 scale); // Create a new physic body dinamically, initialize it and add to pool
+PHYSACDEF void DestroyPhysicBody(PhysicBody pbody);                                     // Destroy a specific physic body and take it out of the list
 
-void ApplyForce(PhysicObject pObj, Vector2 force);                                      // Apply directional force to a physic object
-void ApplyForceAtPosition(Vector2 position, float force, float radius);                 // Apply radial force to all physic objects in range
+PHYSACDEF void ApplyForce(PhysicBody pbody, Vector2 force);                             // Apply directional force to a physic body
+PHYSACDEF void ApplyForceAtPosition(Vector2 position, float force, float radius);       // Apply radial force to all physic objects in range
 
-Rectangle TransformToRectangle(Transform transform);                                    // Convert Transform data type to Rectangle (position and scale)
+PHYSACDEF Rectangle TransformToRectangle(Transform transform);                          // Convert Transform data type to Rectangle (position and scale)
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif // PHYSAC_H
+
+
+/***********************************************************************************
+*
+*   PHYSAC IMPLEMENTATION
+*
+************************************************************************************/
+
+#if defined(PHYSAC_IMPLEMENTATION)
+
+// Check if custom malloc/free functions defined, if not, using standard ones
+#if !defined(PHYSAC_MALLOC)
+    #include <stdlib.h>     // Required for: malloc(), free()
+    
+    #define PHYSAC_MALLOC(size)  malloc(size)
+    #define PHYSAC_FREE(ptr)     free(ptr)
+#endif
+
+#include <math.h>           // Required for: cos(), sin(), abs(), fminf()
+
+//----------------------------------------------------------------------------------
+// Defines and Macros
+//----------------------------------------------------------------------------------
+#define MAX_PHYSIC_BODIES       256             // Maximum available physic bodies slots in bodies pool
+#define PHYSICS_STEPS           450             // Physics update steps number (divided calculations in steps per frame) to get more accurately collisions detections
+#define PHYSICS_ACCURACY        0.0001f         // Velocity subtract operations round filter (friction)
+#define PHYSICS_ERRORPERCENT    0.001f          // Collision resolve position fix
+
+//----------------------------------------------------------------------------------
+// Types and Structures Definition
+// NOTE: Below types are required for PHYSAC_STANDALONE usage
+//----------------------------------------------------------------------------------
+// ...
+
+//----------------------------------------------------------------------------------
+// Global Variables Definition
+//----------------------------------------------------------------------------------
+static PhysicBody physicBodies[MAX_PHYSIC_BODIES];                  // Physic bodies pool
+static int physicBodiesCount;                                       // Counts current enabled physic bodies
+static Vector2 gravityForce;                                        // Gravity force
+
+//----------------------------------------------------------------------------------
+// Module specific Functions Declaration
+//----------------------------------------------------------------------------------
+static float Vector2DotProduct(Vector2 v1, Vector2 v2);             // Returns the dot product of two Vector2
+static float Vector2Length(Vector2 v);                              // Returns the length of a Vector2
+
+//----------------------------------------------------------------------------------
+// Module Functions Definition
+//----------------------------------------------------------------------------------
+
+// Initializes pointers array (just pointers, fixed size)
+PHYSACDEF void InitPhysics(Vector2 gravity)
+{
+    // Initialize physics variables
+    physicBodiesCount = 0;
+    gravityForce = gravity;
+}
+
+// Update physic objects, calculating physic behaviours and collisions detection
+PHYSACDEF void UpdatePhysics()
+{
+    // Reset all physic objects is grounded state
+    for (int i = 0; i < physicBodiesCount; i++) physicBodies[i]->rigidbody.isGrounded = false;
+    
+    for (int steps = 0; steps < PHYSICS_STEPS; steps++)
+    {
+        for (int i = 0; i < physicBodiesCount; i++)
+        {
+            if (physicBodies[i]->enabled)
+            {
+                // Update physic behaviour
+                if (physicBodies[i]->rigidbody.enabled)
+                {
+                    // Apply friction to acceleration in X axis
+                    if (physicBodies[i]->rigidbody.acceleration.x > PHYSICS_ACCURACY) physicBodies[i]->rigidbody.acceleration.x -= physicBodies[i]->rigidbody.friction/PHYSICS_STEPS;
+                    else if (physicBodies[i]->rigidbody.acceleration.x < PHYSICS_ACCURACY) physicBodies[i]->rigidbody.acceleration.x += physicBodies[i]->rigidbody.friction/PHYSICS_STEPS;
+                    else physicBodies[i]->rigidbody.acceleration.x = 0.0f;
+                    
+                    // Apply friction to acceleration in Y axis
+                    if (physicBodies[i]->rigidbody.acceleration.y > PHYSICS_ACCURACY) physicBodies[i]->rigidbody.acceleration.y -= physicBodies[i]->rigidbody.friction/PHYSICS_STEPS;
+                    else if (physicBodies[i]->rigidbody.acceleration.y < PHYSICS_ACCURACY) physicBodies[i]->rigidbody.acceleration.y += physicBodies[i]->rigidbody.friction/PHYSICS_STEPS;
+                    else physicBodies[i]->rigidbody.acceleration.y = 0.0f;
+                    
+                    // Apply friction to velocity in X axis
+                    if (physicBodies[i]->rigidbody.velocity.x > PHYSICS_ACCURACY) physicBodies[i]->rigidbody.velocity.x -= physicBodies[i]->rigidbody.friction/PHYSICS_STEPS;
+                    else if (physicBodies[i]->rigidbody.velocity.x < PHYSICS_ACCURACY) physicBodies[i]->rigidbody.velocity.x += physicBodies[i]->rigidbody.friction/PHYSICS_STEPS;
+                    else physicBodies[i]->rigidbody.velocity.x = 0.0f;
+                    
+                    // Apply friction to velocity in Y axis
+                    if (physicBodies[i]->rigidbody.velocity.y > PHYSICS_ACCURACY) physicBodies[i]->rigidbody.velocity.y -= physicBodies[i]->rigidbody.friction/PHYSICS_STEPS;
+                    else if (physicBodies[i]->rigidbody.velocity.y < PHYSICS_ACCURACY) physicBodies[i]->rigidbody.velocity.y += physicBodies[i]->rigidbody.friction/PHYSICS_STEPS;
+                    else physicBodies[i]->rigidbody.velocity.y = 0.0f;
+                    
+                    // Apply gravity to velocity
+                    if (physicBodies[i]->rigidbody.applyGravity)
+                    {
+                        physicBodies[i]->rigidbody.velocity.x += gravityForce.x/PHYSICS_STEPS;
+                        physicBodies[i]->rigidbody.velocity.y += gravityForce.y/PHYSICS_STEPS;
+                    }
+                    
+                    // Apply acceleration to velocity
+                    physicBodies[i]->rigidbody.velocity.x += physicBodies[i]->rigidbody.acceleration.x/PHYSICS_STEPS;
+                    physicBodies[i]->rigidbody.velocity.y += physicBodies[i]->rigidbody.acceleration.y/PHYSICS_STEPS;
+                    
+                    // Apply velocity to position
+                    physicBodies[i]->transform.position.x += physicBodies[i]->rigidbody.velocity.x/PHYSICS_STEPS;
+                    physicBodies[i]->transform.position.y -= physicBodies[i]->rigidbody.velocity.y/PHYSICS_STEPS;
+                }
+                
+                // Update collision detection
+                if (physicBodies[i]->collider.enabled)
+                {
+                    // Update collider bounds
+                    physicBodies[i]->collider.bounds = TransformToRectangle(physicBodies[i]->transform);
+                    
+                    // Check collision with other colliders
+                    for (int k = 0; k < physicBodiesCount; k++)
+                    {
+                        if (physicBodies[k]->collider.enabled && i != k)
+                        {
+                            // Resolve physic collision
+                            // NOTE: collision resolve is generic for all directions and conditions (no axis separated cases behaviours)
+                            // and it is separated in rigidbody attributes resolve (velocity changes by impulse) and position correction (position overlap)
+                            
+                            // 1. Calculate collision normal
+                            // -------------------------------------------------------------------------------------------------------------------------------------
+                            
+                            // Define collision contact normal, direction and penetration depth
+                            Vector2 contactNormal = { 0.0f, 0.0f };
+                            Vector2 direction = { 0.0f, 0.0f };
+                            float penetrationDepth = 0.0f;
+                            
+                            switch (physicBodies[i]->collider.type)
+                            {
+                                case COLLIDER_RECTANGLE:
+                                {
+                                    switch (physicBodies[k]->collider.type)
+                                    {
+                                        case COLLIDER_RECTANGLE:
+                                        {
+                                            // Check if colliders are overlapped
+                                            if (CheckCollisionRecs(physicBodies[i]->collider.bounds, physicBodies[k]->collider.bounds))
+                                            {
+                                                // Calculate direction vector from i to k
+                                                direction.x = (physicBodies[k]->transform.position.x + physicBodies[k]->transform.scale.x/2) - (physicBodies[i]->transform.position.x + physicBodies[i]->transform.scale.x/2);
+                                                direction.y = (physicBodies[k]->transform.position.y + physicBodies[k]->transform.scale.y/2) - (physicBodies[i]->transform.position.y + physicBodies[i]->transform.scale.y/2);
+                                                
+                                                // Define overlapping and penetration attributes
+                                                Vector2 overlap;
+
+                                                // Calculate overlap on X axis
+                                                overlap.x = (physicBodies[i]->transform.scale.x + physicBodies[k]->transform.scale.x)/2 - abs(direction.x);
+                                                
+                                                // SAT test on X axis
+                                                if (overlap.x > 0.0f)
+                                                {
+                                                    // Calculate overlap on Y axis
+                                                    overlap.y = (physicBodies[i]->transform.scale.y + physicBodies[k]->transform.scale.y)/2 - abs(direction.y);
+                                                    
+                                                    // SAT test on Y axis
+                                                    if (overlap.y > 0.0f)
+                                                    {
+                                                        // Find out which axis is axis of least penetration
+                                                        if (overlap.y > overlap.x)
+                                                        {
+                                                            // Point towards k knowing that direction points from i to k
+                                                            if (direction.x < 0.0f) contactNormal = (Vector2){ -1.0f, 0.0f };
+                                                            else contactNormal = (Vector2){ 1.0f, 0.0f };
+                                                            
+                                                            // Update penetration depth for position correction
+                                                            penetrationDepth = overlap.x;
+                                                        }
+                                                        else
+                                                        {
+                                                            // Point towards k knowing that direction points from i to k
+                                                            if (direction.y < 0.0f) contactNormal = (Vector2){ 0.0f, 1.0f };
+                                                            else contactNormal = (Vector2){ 0.0f, -1.0f };
+                                                            
+                                                            // Update penetration depth for position correction
+                                                            penetrationDepth = overlap.y;
+                                                        }
+                                                    }
+                                                }
+                                            }
+                                        } break;
+                                        case COLLIDER_CIRCLE:
+                                        {
+                                            if (CheckCollisionCircleRec(physicBodies[k]->transform.position, physicBodies[k]->collider.radius, physicBodies[i]->collider.bounds))
+                                            {
+                                                // Calculate direction vector between circles
+                                                direction.x = physicBodies[k]->transform.position.x - physicBodies[i]->transform.position.x + physicBodies[i]->transform.scale.x/2;
+                                                direction.y = physicBodies[k]->transform.position.y - physicBodies[i]->transform.position.y + physicBodies[i]->transform.scale.y/2;
+                                                
+                                                // Calculate closest point on rectangle to circle
+                                                Vector2 closestPoint = { 0.0f, 0.0f };
+                                                if (direction.x > 0.0f) closestPoint.x = physicBodies[i]->collider.bounds.x + physicBodies[i]->collider.bounds.width;
+                                                else closestPoint.x = physicBodies[i]->collider.bounds.x;
+                                                
+                                                if (direction.y > 0.0f) closestPoint.y = physicBodies[i]->collider.bounds.y + physicBodies[i]->collider.bounds.height;
+                                                else closestPoint.y = physicBodies[i]->collider.bounds.y;
+                                                
+                                                // Check if the closest point is inside the circle
+                                                if (CheckCollisionPointCircle(closestPoint, physicBodies[k]->transform.position, physicBodies[k]->collider.radius))
+                                                {
+                                                    // Recalculate direction based on closest point position
+                                                    direction.x = physicBodies[k]->transform.position.x - closestPoint.x;
+                                                    direction.y = physicBodies[k]->transform.position.y - closestPoint.y;
+                                                    float distance = Vector2Length(direction);
+                                                    
+                                                    // Calculate final contact normal
+                                                    contactNormal.x = direction.x/distance;
+                                                    contactNormal.y = -direction.y/distance;
+                                                    
+                                                    // Calculate penetration depth
+                                                    penetrationDepth = physicBodies[k]->collider.radius - distance;
+                                                }
+                                                else
+                                                {
+                                                    if (abs(direction.y) < abs(direction.x))
+                                                    {
+                                                        // Calculate final contact normal
+                                                        if (direction.y > 0.0f)
+                                                        {
+                                                            contactNormal = (Vector2){ 0.0f, -1.0f };
+                                                            penetrationDepth = fabs(physicBodies[i]->collider.bounds.y - physicBodies[k]->transform.position.y - physicBodies[k]->collider.radius);
+                                                        }
+                                                        else 
+                                                        {
+                                                            contactNormal = (Vector2){ 0.0f, 1.0f };
+                                                            penetrationDepth = fabs(physicBodies[i]->collider.bounds.y - physicBodies[k]->transform.position.y + physicBodies[k]->collider.radius);
+                                                        }
+                                                    }
+                                                    else
+                                                    {
+                                                        // Calculate final contact normal
+                                                        if (direction.x > 0.0f)
+                                                        {
+                                                            contactNormal = (Vector2){ 1.0f, 0.0f };
+                                                            penetrationDepth = fabs(physicBodies[k]->transform.position.x + physicBodies[k]->collider.radius - physicBodies[i]->collider.bounds.x);
+                                                        }
+                                                        else 
+                                                        {
+                                                            contactNormal = (Vector2){ -1.0f, 0.0f };
+                                                            penetrationDepth = fabs(physicBodies[i]->collider.bounds.x + physicBodies[i]->collider.bounds.width - physicBodies[k]->transform.position.x - physicBodies[k]->collider.radius);
+                                                        }
+                                                    }
+                                                }
+                                            }
+                                        } break;
+                                    }
+                                } break;
+                                case COLLIDER_CIRCLE:
+                                {
+                                    switch (physicBodies[k]->collider.type)
+                                    {
+                                        case COLLIDER_RECTANGLE:
+                                        {
+                                            if (CheckCollisionCircleRec(physicBodies[i]->transform.position, physicBodies[i]->collider.radius, physicBodies[k]->collider.bounds))
+                                            {
+                                                // Calculate direction vector between circles
+                                                direction.x = physicBodies[k]->transform.position.x + physicBodies[i]->transform.scale.x/2 - physicBodies[i]->transform.position.x;
+                                                direction.y = physicBodies[k]->transform.position.y + physicBodies[i]->transform.scale.y/2 - physicBodies[i]->transform.position.y;
+                                                
+                                                // Calculate closest point on rectangle to circle
+                                                Vector2 closestPoint = { 0.0f, 0.0f };
+                                                if (direction.x > 0.0f) closestPoint.x = physicBodies[k]->collider.bounds.x + physicBodies[k]->collider.bounds.width;
+                                                else closestPoint.x = physicBodies[k]->collider.bounds.x;
+                                                
+                                                if (direction.y > 0.0f) closestPoint.y = physicBodies[k]->collider.bounds.y + physicBodies[k]->collider.bounds.height;
+                                                else closestPoint.y = physicBodies[k]->collider.bounds.y;
+                                                
+                                                // Check if the closest point is inside the circle
+                                                if (CheckCollisionPointCircle(closestPoint, physicBodies[i]->transform.position, physicBodies[i]->collider.radius))
+                                                {
+                                                    // Recalculate direction based on closest point position
+                                                    direction.x = physicBodies[i]->transform.position.x - closestPoint.x;
+                                                    direction.y = physicBodies[i]->transform.position.y - closestPoint.y;
+                                                    float distance = Vector2Length(direction);
+                                                    
+                                                    // Calculate final contact normal
+                                                    contactNormal.x = direction.x/distance;
+                                                    contactNormal.y = -direction.y/distance;
+                                                    
+                                                    // Calculate penetration depth
+                                                    penetrationDepth = physicBodies[k]->collider.radius - distance;
+                                                }
+                                                else
+                                                {
+                                                    if (abs(direction.y) < abs(direction.x))
+                                                    {
+                                                        // Calculate final contact normal
+                                                        if (direction.y > 0.0f)
+                                                        {
+                                                            contactNormal = (Vector2){ 0.0f, -1.0f };
+                                                            penetrationDepth = fabs(physicBodies[k]->collider.bounds.y - physicBodies[i]->transform.position.y - physicBodies[i]->collider.radius);
+                                                        }
+                                                        else 
+                                                        {
+                                                            contactNormal = (Vector2){ 0.0f, 1.0f };
+                                                            penetrationDepth = fabs(physicBodies[k]->collider.bounds.y - physicBodies[i]->transform.position.y + physicBodies[i]->collider.radius);
+                                                        }
+                                                    }
+                                                    else
+                                                    {
+                                                        // Calculate final contact normal and penetration depth
+                                                        if (direction.x > 0.0f)
+                                                        {
+                                                            contactNormal = (Vector2){ 1.0f, 0.0f };
+                                                            penetrationDepth = fabs(physicBodies[i]->transform.position.x + physicBodies[i]->collider.radius - physicBodies[k]->collider.bounds.x);
+                                                        }
+                                                        else 
+                                                        {
+                                                            contactNormal = (Vector2){ -1.0f, 0.0f };
+                                                            penetrationDepth = fabs(physicBodies[k]->collider.bounds.x + physicBodies[k]->collider.bounds.width - physicBodies[i]->transform.position.x - physicBodies[i]->collider.radius);
+                                                        }
+                                                    }
+                                                }
+                                            }
+                                        } break;
+                                        case COLLIDER_CIRCLE:
+                                        {
+                                            // Check if colliders are overlapped
+                                            if (CheckCollisionCircles(physicBodies[i]->transform.position, physicBodies[i]->collider.radius, physicBodies[k]->transform.position, physicBodies[k]->collider.radius))
+                                            {
+                                                // Calculate direction vector between circles
+                                                direction.x = physicBodies[k]->transform.position.x - physicBodies[i]->transform.position.x;
+                                                direction.y = physicBodies[k]->transform.position.y - physicBodies[i]->transform.position.y;
+                                                
+                                                // Calculate distance between circles
+                                                float distance = Vector2Length(direction);
+                                                
+                                                // Check if circles are not completely overlapped
+                                                if (distance != 0.0f)
+                                                {                                                    
+                                                    // Calculate contact normal direction (Y axis needs to be flipped)
+                                                    contactNormal.x = direction.x/distance;
+                                                    contactNormal.y = -direction.y/distance;
+                                                }
+                                                else contactNormal = (Vector2){ 1.0f, 0.0f };   // Choose random (but consistent) values
+                                            }
+                                        } break;
+                                        default: break;
+                                    }
+                                } break;
+                                default: break;
+                            }
+                            
+                            // Update rigidbody grounded state
+                            if (physicBodies[i]->rigidbody.enabled)
+                            {
+                                if (contactNormal.y < 0.0f) physicBodies[i]->rigidbody.isGrounded = true;
+                            }
+                            
+                            // 2. Calculate collision impulse
+                            // -------------------------------------------------------------------------------------------------------------------------------------
+                            
+                            // Calculate relative velocity
+                            Vector2 relVelocity = { 0.0f, 0.0f };
+                            relVelocity.x = physicBodies[k]->rigidbody.velocity.x - physicBodies[i]->rigidbody.velocity.x;
+                            relVelocity.y = physicBodies[k]->rigidbody.velocity.y - physicBodies[i]->rigidbody.velocity.y;
+
+                            // Calculate relative velocity in terms of the normal direction
+                            float velAlongNormal = Vector2DotProduct(relVelocity, contactNormal);
+                        
+                            // Dot not resolve if velocities are separating
+                            if (velAlongNormal <= 0.0f)
+                            {
+                                // Calculate minimum bounciness value from both objects
+                                float e = fminf(physicBodies[i]->rigidbody.bounciness, physicBodies[k]->rigidbody.bounciness);
+                                
+                                // Calculate impulse scalar value
+                                float j = -(1.0f + e)*velAlongNormal;
+                                j /= 1.0f/physicBodies[i]->rigidbody.mass + 1.0f/physicBodies[k]->rigidbody.mass;
+                                
+                                // Calculate final impulse vector
+                                Vector2 impulse = { j*contactNormal.x, j*contactNormal.y };
+                                
+                                // Calculate collision mass ration
+                                float massSum = physicBodies[i]->rigidbody.mass + physicBodies[k]->rigidbody.mass;
+                                float ratio = 0.0f;
+                                
+                                // Apply impulse to current rigidbodies velocities if they are enabled
+                                if (physicBodies[i]->rigidbody.enabled) 
+                                {
+                                    // Calculate inverted mass ration
+                                    ratio = physicBodies[i]->rigidbody.mass/massSum;
+                                    
+                                    // Apply impulse direction to velocity
+                                    physicBodies[i]->rigidbody.velocity.x -= impulse.x*ratio*(1.0f+physicBodies[i]->rigidbody.bounciness);
+                                    physicBodies[i]->rigidbody.velocity.y -= impulse.y*ratio*(1.0f+physicBodies[i]->rigidbody.bounciness);
+                                }
+                                
+                                if (physicBodies[k]->rigidbody.enabled) 
+                                {
+                                    // Calculate inverted mass ration
+                                    ratio = physicBodies[k]->rigidbody.mass/massSum;
+                                    
+                                    // Apply impulse direction to velocity
+                                    physicBodies[k]->rigidbody.velocity.x += impulse.x*ratio*(1.0f+physicBodies[i]->rigidbody.bounciness);
+                                    physicBodies[k]->rigidbody.velocity.y += impulse.y*ratio*(1.0f+physicBodies[i]->rigidbody.bounciness);
+                                }
+                                
+                                // 3. Correct colliders overlaping (transform position)
+                                // ---------------------------------------------------------------------------------------------------------------------------------
+                                
+                                // Calculate transform position penetration correction
+                                Vector2 posCorrection;
+                                posCorrection.x = penetrationDepth/((1.0f/physicBodies[i]->rigidbody.mass) + (1.0f/physicBodies[k]->rigidbody.mass))*PHYSICS_ERRORPERCENT*contactNormal.x;
+                                posCorrection.y = penetrationDepth/((1.0f/physicBodies[i]->rigidbody.mass) + (1.0f/physicBodies[k]->rigidbody.mass))*PHYSICS_ERRORPERCENT*contactNormal.y;
+                                
+                                // Fix transform positions
+                                if (physicBodies[i]->rigidbody.enabled)
+                                {                                        
+                                    // Fix physic objects transform position
+                                    physicBodies[i]->transform.position.x -= 1.0f/physicBodies[i]->rigidbody.mass*posCorrection.x;
+                                    physicBodies[i]->transform.position.y += 1.0f/physicBodies[i]->rigidbody.mass*posCorrection.y;
+                                    
+                                    // Update collider bounds
+                                    physicBodies[i]->collider.bounds = TransformToRectangle(physicBodies[i]->transform);
+                                    
+                                    if (physicBodies[k]->rigidbody.enabled)
+                                    {
+                                        // Fix physic objects transform position
+                                        physicBodies[k]->transform.position.x += 1.0f/physicBodies[k]->rigidbody.mass*posCorrection.x;
+                                        physicBodies[k]->transform.position.y -= 1.0f/physicBodies[k]->rigidbody.mass*posCorrection.y;
+                                        
+                                        // Update collider bounds
+                                        physicBodies[k]->collider.bounds = TransformToRectangle(physicBodies[k]->transform);
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+// Unitialize all physic objects and empty the objects pool
+PHYSACDEF void ClosePhysics()
+{
+    // Free all dynamic memory allocations
+    for (int i = 0; i < physicBodiesCount; i++) PHYSAC_FREE(physicBodies[i]);
+    
+    // Reset enabled physic objects count
+    physicBodiesCount = 0;
+}
+
+// Create a new physic body dinamically, initialize it and add to pool
+PHYSACDEF PhysicBody CreatePhysicBody(Vector2 position, float rotation, Vector2 scale)
+{
+    // Allocate dynamic memory
+    PhysicBody obj = (PhysicBody)PHYSAC_MALLOC(sizeof(PhysicBodyData));
+    
+    // Initialize physic body values with generic values
+    obj->id = physicBodiesCount;
+    obj->enabled = true;
+    
+    obj->transform = (Transform){ (Vector2){ position.x - scale.x/2, position.y - scale.y/2 }, rotation, scale };
+    
+    obj->rigidbody.enabled = false;
+    obj->rigidbody.mass = 1.0f;
+    obj->rigidbody.acceleration = (Vector2){ 0.0f, 0.0f };
+    obj->rigidbody.velocity = (Vector2){ 0.0f, 0.0f };
+    obj->rigidbody.applyGravity = false;
+    obj->rigidbody.isGrounded = false;
+    obj->rigidbody.friction = 0.0f;
+    obj->rigidbody.bounciness = 0.0f;
+    
+    obj->collider.enabled = true;
+    obj->collider.type = COLLIDER_RECTANGLE;
+    obj->collider.bounds = TransformToRectangle(obj->transform);
+    obj->collider.radius = 0.0f;
+    
+    // Add new physic body to the pointers array
+    physicBodies[physicBodiesCount] = obj;
+    
+    // Increase enabled physic bodies count
+    physicBodiesCount++;
+    
+    return obj;
+}
+
+// Destroy a specific physic body and take it out of the list
+PHYSACDEF void DestroyPhysicBody(PhysicBody pbody)
+{
+    // Free dynamic memory allocation
+    PHYSAC_FREE(physicBodies[pbody->id]);
+    
+    // Remove *obj from the pointers array
+    for (int i = pbody->id; i < physicBodiesCount; i++)
+    {
+        // Resort all the following pointers of the array
+        if ((i + 1) < physicBodiesCount)
+        {
+            physicBodies[i] = physicBodies[i + 1];
+            physicBodies[i]->id = physicBodies[i + 1]->id;
+        }
+        else PHYSAC_FREE(physicBodies[i]);
+    }
+    
+    // Decrease enabled physic bodies count
+    physicBodiesCount--;
+}
+
+// Apply directional force to a physic body
+PHYSACDEF void ApplyForce(PhysicBody pbody, Vector2 force)
+{
+    if (pbody->rigidbody.enabled)
+    {
+        pbody->rigidbody.velocity.x += force.x/pbody->rigidbody.mass;
+        pbody->rigidbody.velocity.y += force.y/pbody->rigidbody.mass;
+    }
+}
+
+// Apply radial force to all physic objects in range
+PHYSACDEF void ApplyForceAtPosition(Vector2 position, float force, float radius)
+{
+    for (int i = 0; i < physicBodiesCount; i++)
+    {
+        if (physicBodies[i]->rigidbody.enabled)
+        {
+            // Calculate direction and distance between force and physic body position
+            Vector2 distance = (Vector2){ physicBodies[i]->transform.position.x - position.x, physicBodies[i]->transform.position.y - position.y };
+
+            if (physicBodies[i]->collider.type == COLLIDER_RECTANGLE)
+            {
+                distance.x += physicBodies[i]->transform.scale.x/2;
+                distance.y += physicBodies[i]->transform.scale.y/2;
+            }
+            
+            float distanceLength = Vector2Length(distance);
+            
+            // Check if physic body is in force range
+            if (distanceLength <= radius)
+            {
+                // Normalize force direction
+                distance.x /= distanceLength;
+                distance.y /= -distanceLength;
+                
+                // Calculate final force
+                Vector2 finalForce = { distance.x*force, distance.y*force };
+                
+                // Apply force to the physic body
+                ApplyForce(physicBodies[i], finalForce);
+            }
+        }
+    }
+}
+
+// Convert Transform data type to Rectangle (position and scale)
+PHYSACDEF Rectangle TransformToRectangle(Transform transform)
+{
+    return (Rectangle){transform.position.x, transform.position.y, transform.scale.x, transform.scale.y};
+}
+
+//----------------------------------------------------------------------------------
+// Module specific Functions Definition
+//----------------------------------------------------------------------------------
+
+// Returns the dot product of two Vector2
+static float Vector2DotProduct(Vector2 v1, Vector2 v2)
+{
+    float result;
+
+    result = v1.x*v2.x + v1.y*v2.y;
+
+    return result;
+}
+
+static float Vector2Length(Vector2 v)
+{
+    float result;
+    
+    result = sqrt(v.x*v.x + v.y*v.y);
+    
+    return result;
+}
+
+#endif  // PHYSAC_IMPLEMENTATION
\ No newline at end of file