Added physics engine-module and example

- Added new physics engine-module with four new data types: Physics,
Transform, Rigidbody and Collider. This library contains functions to
apply physics calculations to a position vector calculating collisions
automatically.

- Fixed some writing mistakes of lighting module.

examples/lighting_blinn_phong.c

@@ -1,11 +1,21 @@
 /*******************************************************************************************
 *
-*   raylib - Phong lighting shader example
+*   raylib [lighting] example - Basic Phong lighting
 *
-*   This example has been created using raylib v1.3.0 (www.raylib.com)
+*   Welcome to raylib!
+*
+*   To test examples, just press F6 and execute raylib_compile_execute script
+*   Note that compiled executable is placed in the same folder as .c file
+*
+*   You can find all basic examples on C:\raylib\raylib\examples folder or
+*   raylib official webpage: www.raylib.com
+*
+*   Enjoy using raylib. :)
+*
+*   This example has been created using raylib 1.3 (www.raylib.com)
 *   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
 *
-*   Copyright (c) 2015 Ramon Santamaria (Ray San - [email protected])
+*   Copyright (c) 2015 Ramon Santamaria (@raysan5)
 *
 ********************************************************************************************/
 
@@ -22,7 +32,7 @@ int main()
     const int screenHeight = 450;
     
     SetConfigFlags(FLAG_MSAA_4X_HINT);
-    InitWindow(screenWidth, screenHeight, "raylib [lighting] example - basic blinn-phong lighting");
+    InitWindow(screenWidth, screenHeight, "raylib [lighting] example - blinn phong lighting");
     SetTargetFPS(60);
     
     // Camera initialization

examples/physics_basic_rigidbody.c

@@ -0,0 +1,144 @@
+/*******************************************************************************************
+*
+*   raylib [physics] example - Basic rigidbody
+*
+*   Welcome to raylib!
+*
+*   To test examples, just press F6 and execute raylib_compile_execute script
+*   Note that compiled executable is placed in the same folder as .c file
+*
+*   You can find all basic examples on C:\raylib\raylib\examples folder or
+*   raylib official webpage: www.raylib.com
+*
+*   Enjoy using raylib. :)
+*
+*   This example has been created using raylib 1.3 (www.raylib.com)
+*   raylib is licensed under an unmodified zlib/libpng license (View raylib.h for details)
+*
+*   Copyright (c) 2015 Ramon Santamaria (@raysan5)
+*
+********************************************************************************************/
+
+#include "raylib.h"
+
+#define OBJECT_SIZE 50
+#define PLAYER_INDEX 0
+
+int main()
+{
+    // Initialization
+    //--------------------------------------------------------------------------------------
+    int screenWidth = 800;
+    int screenHeight = 450;
+    
+    InitWindow(screenWidth, screenHeight, "raylib [physics] example - basic rigidbody");
+    SetTargetFPS(60);   // Enable v-sync
+    InitPhysics();      // Initialize internal physics values   (max rigidbodies/colliders available: 1024)
+    
+    // Physics initialization
+    Physics worldPhysics = {true, false, (Vector2){0, -9.81f}};
+    
+    // Set internal physics settings
+    SetPhysics(worldPhysics);
+    
+    // Object initialization
+    Transform player = (Transform){(Vector2){(screenWidth - OBJECT_SIZE) / 2, (screenHeight - OBJECT_SIZE) / 2}, 0.0f, (Vector2){OBJECT_SIZE, OBJECT_SIZE}};
+    AddCollider(PLAYER_INDEX, (Collider){true, RectangleCollider, (Rectangle){player.position.x, player.position.y, player.scale.x, player.scale.y}, 0});
+    AddRigidbody(PLAYER_INDEX, (Rigidbody){true, 1.0f, (Vector2){0, 0}, (Vector2){0, 0}, false, false, true, 0.5f, 1.0f});
+    
+    // Floor initialization 
+    // NOTE: floor doesn't need a rigidbody because it's a static physic object, just a collider to collide with other dynamic colliders (with rigidbody)
+    Transform floor = (Transform){(Vector2){0, screenHeight * 0.8f}, 0.0f, (Vector2){screenWidth, screenHeight * 0.2f}};
+    AddCollider(PLAYER_INDEX + 1, (Collider){true, RectangleCollider, (Rectangle){floor.position.x, floor.position.y, floor.scale.x, floor.scale.y}, 0});
+    
+    // Object properties initialization
+    float moveSpeed = 6.0f;
+    float jumpForce = 4.5f;
+    //--------------------------------------------------------------------------------------
+
+    // Main game loop
+    while (!WindowShouldClose())    // Detect window close button or ESC key
+    {
+        // Update
+        //----------------------------------------------------------------------------------
+        
+        // Update object physics 
+        // NOTE: all physics detections and reactions are calculated in ApplyPhysics() function (You will live happier :D)
+        ApplyPhysics(PLAYER_INDEX, &player.position);
+        
+        // Check jump button input
+        if(IsKeyDown(KEY_SPACE) && GetRigidbody(PLAYER_INDEX).isGrounded)
+        {
+            // Reset object Y velocity to avoid double jumping cases but keep the same X velocity that it already has
+            SetRigidbodyVelocity(PLAYER_INDEX, (Vector2){GetRigidbody(PLAYER_INDEX).velocity.x, 0});
+            
+            // Add jumping force in Y axis
+            AddRigidbodyForce(PLAYER_INDEX, (Vector2){0, jumpForce});
+        }
+        
+        // Check movement buttons input
+        if(IsKeyDown(KEY_RIGHT) || IsKeyDown(KEY_D))
+        {
+            // Set rigidbody velocity in X based on moveSpeed value and apply the same Y velocity that it already has
+            SetRigidbodyVelocity(PLAYER_INDEX, (Vector2){moveSpeed, GetRigidbody(PLAYER_INDEX).velocity.y});
+        }
+        else if(IsKeyDown(KEY_LEFT) || IsKeyDown(KEY_A))
+        {
+            // Set rigidbody velocity in X based on moveSpeed negative value and apply the same Y velocity that it already has
+            SetRigidbodyVelocity(PLAYER_INDEX, (Vector2){-moveSpeed, GetRigidbody(PLAYER_INDEX).velocity.y});
+        }
+        
+        // Check debug mode toggle button input
+        if(IsKeyPressed(KEY_P))
+        {
+            // Update program physics value
+            worldPhysics.debug = !worldPhysics.debug;
+            
+            // Update internal physics value
+            SetPhysics(worldPhysics);
+        }
+        //----------------------------------------------------------------------------------
+
+        // Draw
+        //----------------------------------------------------------------------------------
+        BeginDrawing();
+
+            ClearBackground(RAYWHITE);
+            
+            // Draw information
+            DrawText("Use LEFT / RIGHT to MOVE and SPACE to JUMP", (screenWidth - MeasureText("Use LEFT / RIGHT to MOVE and SPACE to JUMP", 20)) / 2, screenHeight * 0.20f, 20, LIGHTGRAY);
+            DrawText("Use P to switch DEBUG MODE", (screenWidth - MeasureText("Use P to switch DEBUG MODE", 20)) / 2, screenHeight * 0.3f, 20, LIGHTGRAY);
+            
+            // Check if debug mode is enabled
+            if(worldPhysics.debug)
+            {
+                // Draw every internal physics stored collider if it is active
+                for(int i = 0; i < 2; i++)
+                {
+                    if(GetCollider(i).enabled)
+                    {
+                        DrawRectangleLines(GetCollider(i).bounds.x, GetCollider(i).bounds.y, GetCollider(i).bounds.width, GetCollider(i).bounds.height, GREEN);
+                    }
+                }
+                
+            }
+            else
+            {
+                // Draw player
+                DrawRectangleRec((Rectangle){player.position.x, player.position.y, player.scale.x, player.scale.y}, GRAY);
+                
+                // Draw floor
+                DrawRectangleRec((Rectangle){floor.position.x, floor.position.y, floor.scale.x, floor.scale.y}, BLACK);
+            }
+
+        EndDrawing();
+        //----------------------------------------------------------------------------------
+    }
+
+    // De-Initialization
+    //--------------------------------------------------------------------------------------   
+    CloseWindow();        // Close window and OpenGL context
+    //--------------------------------------------------------------------------------------
+
+    return 0;
+}

src/lighting.c

@@ -42,7 +42,7 @@
 //...
 
 //----------------------------------------------------------------------------------
-// Module Functions Definition
+// Module Functions Declarations
 //----------------------------------------------------------------------------------
 
 // Lights functions

src/lighting.h

@@ -61,7 +61,7 @@ typedef struct Material {
 } Material;
 
 //----------------------------------------------------------------------------------
-// Module Functions Declaration 
+// Module Functions Definitions
 // NOTE: light and material structs uses float pointers instead of vectors to be compatible with SetShaderValue()
 //----------------------------------------------------------------------------------
 // Lights functions

src/physics.c

@@ -0,0 +1,272 @@
+/**********************************************************************************************
+*
+*   raylib physics engine module - Basic functions to apply physics to 2D objects
+*
+*   Copyright (c) 2015 Victor Fisac 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.
+*
+*   Permission is granted to anyone to use this software for any purpose, including commercial
+*   applications, and to alter it and redistribute it freely, subject to the following restrictions:
+*
+*     1. The origin of this software must not be misrepresented; you must not claim that you
+*     wrote the original software. If you use this software in a product, an acknowledgment
+*     in the product documentation would be appreciated but is not required.
+*
+*     2. Altered source versions must be plainly marked as such, and must not be misrepresented
+*     as being the original software.
+*
+*     3. This notice may not be removed or altered from any source distribution.
+*
+**********************************************************************************************/
+
+//#define PHYSICS_STANDALONE     // NOTE: To use the physics module as standalone lib, just uncomment this line
+
+#if defined(PHYSICS_STANDALONE)
+    #include "physics.h"
+#else
+    #include "raylib.h"
+#endif
+
+#include <math.h>
+#include <stdio.h>
+
+//----------------------------------------------------------------------------------
+// Defines and Macros
+//----------------------------------------------------------------------------------
+#define MAX_ELEMENTS 1024       // Stored rigidbodies and colliders array length
+#define DECIMAL_FIX 0.01f       // Decimal margin for collision checks (avoid rigidbodies shake)
+
+//----------------------------------------------------------------------------------
+// Types and Structures Definition
+//----------------------------------------------------------------------------------
+// ...
+
+//----------------------------------------------------------------------------------
+// Global Variables Definition
+//----------------------------------------------------------------------------------
+static Physics physics;
+static Collider colliders[MAX_ELEMENTS];
+static Rigidbody rigidbodies[MAX_ELEMENTS];
+static bool collisionChecker = false;
+
+//----------------------------------------------------------------------------------
+// Module Functions Definition
+//----------------------------------------------------------------------------------
+void InitPhysics()
+{    
+    for (int i = 0; i < MAX_ELEMENTS; i++)
+    {
+        rigidbodies[i].enabled = false;
+        rigidbodies[i].mass = 0.0f;
+        rigidbodies[i].velocity = (Vector2){0, 0};
+        rigidbodies[i].acceleration = (Vector2){0, 0};
+        rigidbodies[i].isGrounded = false;
+        rigidbodies[i].isContact = false;
+        rigidbodies[i].friction = 0.0f;
+        
+        colliders[i].enabled = false;
+        colliders[i].bounds = (Rectangle){0, 0, 0, 0};
+        colliders[i].radius = 0;
+    }
+}
+
+void SetPhysics(Physics settings)
+{
+    physics = settings;
+    
+    // To get good results, gravity needs to be 1:10 from original parameter
+    physics.gravity = (Vector2){physics.gravity.x / 10, physics.gravity.y / 10};
+}
+
+void AddCollider(int index, Collider collider)
+{
+    colliders[index] = collider;
+}
+
+void AddRigidbody(int index, Rigidbody rigidbody)
+{
+    rigidbodies[index] = rigidbody;
+}
+
+void ApplyPhysics(int index, Vector2 *position)
+{
+    if (rigidbodies[index].enabled)
+    {
+        // Apply gravity
+        rigidbodies[index].velocity.y += rigidbodies[index].acceleration.y;
+        rigidbodies[index].velocity.x += rigidbodies[index].acceleration.x;
+        
+        rigidbodies[index].velocity.y += physics.gravity.y;
+        rigidbodies[index].velocity.x += physics.gravity.x;
+        
+        // Apply friction to velocity
+        if (rigidbodies[index].isGrounded)
+        {
+            if (rigidbodies[index].velocity.x > DECIMAL_FIX)
+            {
+                rigidbodies[index].velocity.x -= rigidbodies[index].friction;
+            }
+            else if (rigidbodies[index].velocity.x < -DECIMAL_FIX)
+            {
+                rigidbodies[index].velocity.x += rigidbodies[index].friction;
+            }
+            else
+            {
+                rigidbodies[index].velocity.x = 0;
+            }
+        }
+        
+        if (rigidbodies[index].velocity.y > DECIMAL_FIX)
+        {
+            rigidbodies[index].velocity.y -= rigidbodies[index].friction;
+        }
+        else if (rigidbodies[index].velocity.y < -DECIMAL_FIX)
+        {
+            rigidbodies[index].velocity.y += rigidbodies[index].friction;
+        }
+        else
+        {
+            rigidbodies[index].velocity.y = 0;
+        }
+        
+        // Apply friction to acceleration
+        if (rigidbodies[index].isGrounded)
+        {
+            if (rigidbodies[index].acceleration.x > DECIMAL_FIX)
+            {
+                rigidbodies[index].acceleration.x -= rigidbodies[index].friction;
+            }
+            else if (rigidbodies[index].acceleration.x < -DECIMAL_FIX)
+            {
+                rigidbodies[index].acceleration.x += rigidbodies[index].friction;
+            }
+            else
+            {
+                rigidbodies[index].acceleration.x = 0;
+            }
+        }
+        
+        if (rigidbodies[index].acceleration.y > DECIMAL_FIX)
+        {
+            rigidbodies[index].acceleration.y -= rigidbodies[index].friction;
+        }
+        else if (rigidbodies[index].acceleration.y < -DECIMAL_FIX)
+        {
+            rigidbodies[index].acceleration.y += rigidbodies[index].friction;
+        }
+        else
+        {
+            rigidbodies[index].acceleration.y = 0;
+        }
+        
+        // Update position vector
+        position->x += rigidbodies[index].velocity.x;        
+        position->y -= rigidbodies[index].velocity.y;
+        
+        // Update collider bounds
+        colliders[index].bounds.x = position->x;
+        colliders[index].bounds.y = position->y;
+        
+        // Check collision with other colliders
+        collisionChecker = false;
+        rigidbodies[index].isContact = false;
+        for (int j = 0; j < MAX_ELEMENTS; j++)
+        {
+            if (index != j)
+            {
+                if (colliders[index].enabled && colliders[j].enabled)
+                {
+                    if (colliders[index].type == RectangleCollider)
+                    {
+                        if (colliders[j].type == RectangleCollider)
+                        {
+                            if (CheckCollisionRecs(colliders[index].bounds, colliders[j].bounds))
+                            {
+                                collisionChecker = true;
+                                
+                                if ((colliders[index].bounds.y + colliders[index].bounds.height <= colliders[j].bounds.y) == false)
+                                {
+                                    rigidbodies[index].isContact = true;
+                                }
+                            }
+                        }
+                        else
+                        {
+                            if (CheckCollisionCircleRec((Vector2){colliders[j].bounds.x, colliders[j].bounds.y}, colliders[j].radius, colliders[index].bounds))
+                            {
+                                collisionChecker = true;
+                            }
+                        }
+                    }
+                    else
+                    {
+                        if (colliders[j].type == RectangleCollider)
+                        {
+                            if (CheckCollisionCircleRec((Vector2){colliders[index].bounds.x, colliders[index].bounds.y}, colliders[index].radius, colliders[j].bounds))
+                            {
+                                collisionChecker = true;
+                            }
+                        }
+                        else
+                        {
+                            if (CheckCollisionCircles((Vector2){colliders[j].bounds.x, colliders[j].bounds.y}, colliders[j].radius, (Vector2){colliders[index].bounds.x, colliders[index].bounds.y}, colliders[index].radius))
+                            {
+                                collisionChecker = true;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+        
+        // Update grounded rigidbody state
+        rigidbodies[index].isGrounded = collisionChecker;
+        
+        // Set grounded state if needed (fix overlap and set y velocity)
+        if (collisionChecker && rigidbodies[index].velocity.y != 0)
+        {
+            position->y += rigidbodies[index].velocity.y;
+            rigidbodies[index].velocity.y = -rigidbodies[index].velocity.y * rigidbodies[index].bounciness;
+        }
+        
+        if (rigidbodies[index].isContact)
+        {
+            position->x -= rigidbodies[index].velocity.x;
+            rigidbodies[index].velocity.x = rigidbodies[index].velocity.x;
+        }
+    }
+}
+
+void SetRigidbodyEnabled(int index, bool state)
+{
+    rigidbodies[index].enabled = state;
+}
+
+void SetRigidbodyVelocity(int index, Vector2 velocity)
+{
+    rigidbodies[index].velocity.x = velocity.x;
+    rigidbodies[index].velocity.y = velocity.y;
+}
+
+void AddRigidbodyForce(int index, Vector2 force)
+{
+    rigidbodies[index].acceleration.x = force.x * rigidbodies[index].mass;
+    rigidbodies[index].acceleration.y = force.y * rigidbodies[index].mass;
+}
+
+void SetColliderEnabled(int index, bool state)
+{
+    colliders[index].enabled = state;
+}
+
+Collider GetCollider(int index)
+{
+    return colliders[index];
+}
+
+Rigidbody GetRigidbody(int index)
+{
+    return rigidbodies[index];
+}

src/physics.h

@@ -0,0 +1,99 @@
+/**********************************************************************************************
+*
+*   raylib physics engine module - Basic functions to apply physics to 2D objects
+*
+*   Copyright (c) 2015 Victor Fisac 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.
+*
+*   Permission is granted to anyone to use this software for any purpose, including commercial
+*   applications, and to alter it and redistribute it freely, subject to the following restrictions:
+*
+*     1. The origin of this software must not be misrepresented; you must not claim that you
+*     wrote the original software. If you use this software in a product, an acknowledgment
+*     in the product documentation would be appreciated but is not required.
+*
+*     2. Altered source versions must be plainly marked as such, and must not be misrepresented
+*     as being the original software.
+*
+*     3. This notice may not be removed or altered from any source distribution.
+*
+**********************************************************************************************/
+
+#ifndef PHYSICS_H
+#define PHYSICS_H
+
+//----------------------------------------------------------------------------------
+// Defines and Macros
+//----------------------------------------------------------------------------------
+// ...
+
+//----------------------------------------------------------------------------------
+// Types and Structures Definition
+//----------------------------------------------------------------------------------
+typedef enum { RectangleCollider, CircleCollider } ColliderType;
+
+// Physics struct
+typedef struct Physics {
+    bool enabled;
+    bool debug;     // Should be used by programmer for testing purposes
+    Vector2 gravity;
+} Physics;
+
+// Transform struct
+typedef struct Transform {
+    Vector2 position;
+    float rotation;
+    Vector2 scale;
+} Transform;
+
+// Rigidbody struct
+typedef struct Rigidbody {
+    bool enabled;
+    float mass;
+    Vector2 acceleration;
+    Vector2 velocity;
+    bool isGrounded;
+    bool isContact;     // Avoid freeze player when touching floor
+    bool applyGravity;
+    float friction;     // 0.0f to 1.0f
+    float bounciness;   // 0.0f to 1.0f
+} Rigidbody;
+
+// Collider struct
+typedef struct Collider {
+    bool enabled;
+    ColliderType type;
+    Rectangle bounds;   // Just used for RectangleCollider type
+    int radius;     // Just used for CircleCollider type
+} Collider;
+
+#ifdef __cplusplus
+extern "C" {            // Prevents name mangling of functions
+#endif
+
+//----------------------------------------------------------------------------------
+// Module Functions Declaration
+//----------------------------------------------------------------------------------
+void InitPhysics();                                                     // Initialize all internal physics values
+void SetPhysics(Physics settings);                                      // Set physics settings values using Physics data type to overwrite internal physics settings
+
+void AddRigidbody(int index, Rigidbody rigidbody);                      // Initialize a new rigidbody with parameters to internal index slot
+void AddCollider(int index, Collider collider);                         // Initialize a new Collider with parameters to internal index slot
+
+void ApplyPhysics(int index, Vector2 *position);                        // Apply physics to internal rigidbody, physics calculations are applied to position pointer parameter
+void SetRigidbodyEnabled(int index, bool state);                        // Set enabled state to a defined rigidbody
+void SetRigidbodyVelocity(int index, Vector2 velocity);                 // Set velocity of rigidbody (without considering of mass value)
+void AddRigidbodyForce(int index, Vector2 force);                       // Set rigidbody force (considering mass value)
+
+void SetColliderEnabled(int index, bool state);                         // Set enabled state to a defined collider
+
+Rigidbody GetRigidbody(int index);                                      // Returns the internal rigidbody data defined by index parameter
+Collider GetCollider(int index);                                        // Returns the internal collider data defined by index parameter
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // PHYSICS_H

src/raylib.h

@@ -433,6 +433,44 @@ typedef enum {
 // Camera system modes
 typedef enum { CAMERA_CUSTOM = 0, CAMERA_FREE, CAMERA_ORBITAL, CAMERA_FIRST_PERSON, CAMERA_THIRD_PERSON } CameraMode;
 
+// Collider types
+typedef enum { RectangleCollider, CircleCollider } ColliderType;
+
+// Physics struct
+typedef struct Physics {
+    bool enabled;
+    bool debug;     // Should be used by programmer for testing purposes
+    Vector2 gravity;
+} Physics;
+
+// Transform struct
+typedef struct Transform {
+    Vector2 position;
+    float rotation;
+    Vector2 scale;
+} Transform;
+
+// Rigidbody struct
+typedef struct Rigidbody {
+    bool enabled;
+    float mass;
+    Vector2 acceleration;
+    Vector2 velocity;
+    bool isGrounded;
+    bool isContact;     // Avoid freeze player when touching floor
+    bool applyGravity;
+    float friction;     // 0.0f to 1.0f
+    float bounciness;   // 0.0f to 1.0f
+} Rigidbody;
+
+// Collider struct
+typedef struct Collider {
+    bool enabled;
+    ColliderType type;
+    Rectangle bounds;   // Just used for RectangleCollider type
+    int radius;         // Just used for CircleCollider type
+} Collider;
+
 #ifdef __cplusplus
 extern "C" {            // Prevents name mangling of functions
 #endif
@@ -742,6 +780,25 @@ void SetMaterialSpecularColor(Material *material, Vector3 color);       // Set m
 void SetMaterialGlossiness(Material *material, float glossiness);       // Set material glossiness value (recommended values: 0 - 100)
 void SetMaterialNormalDepth(Material *material, float depth);           // Set normal map depth (B component from RGB type map scalar multiplier)
 
+//----------------------------------------------------------------------------------
+// Physics System Functions (engine-module: physics)
+//----------------------------------------------------------------------------------
+void InitPhysics();                                                     // Initialize all internal physics values
+void SetPhysics(Physics settings);                                      // Set physics settings values using Physics data type to overwrite internal physics settings
+
+void AddRigidbody(int index, Rigidbody rigidbody);                      // Initialize a new rigidbody with parameters to internal index slot
+void AddCollider(int index, Collider collider);                         // Initialize a new Collider with parameters to internal index slot
+
+void ApplyPhysics(int index, Vector2 *position);                        // Apply physics to internal rigidbody, physics calculations are applied to position pointer parameter
+void SetRigidbodyEnabled(int index, bool state);                        // Set enabled state to a defined rigidbody
+void SetRigidbodyVelocity(int index, Vector2 velocity);                 // Set velocity of rigidbody (without considering of mass value)
+void AddRigidbodyForce(int index, Vector2 force);                       // Set rigidbody force (considering mass value)
+
+void SetColliderEnabled(int index, bool state);                         // Set enabled state to a defined collider
+
+Rigidbody GetRigidbody(int index);                                      // Returns the internal rigidbody data defined by index parameter
+Collider GetCollider(int index);                                        // Returns the internal collider data defined by index parameter
+
 //------------------------------------------------------------------------------------
 // Audio Loading and Playing Functions (Module: audio)
 //------------------------------------------------------------------------------------