Box2D "hello world" example implemented. Graphics system does not support rotation yet.

docs/core.todo

@@ -17,6 +17,7 @@ Core:
         ✔ Implement the Image creation methods @done (9/9/2021, 2:50:20 PM)
         ✔ Implement Render to Texture @done (9/15/2021, 7:00:33 PM)
         ✔ Adjust the font loading code to use the binary file buffer instead of ifstream @done (9/17/2021, 6:11:06 PM)
+        ☐ Find a way to add rotation to shapes and images
 
         
         GUI:
@@ -33,7 +34,8 @@ Core:
     Physics:
         ✔ Research Box2D as a possible physics library @done (10/27/2021, 7:40:44 PM)
         ✔ Add Box2D to the project as an external library @done (10/27/2021, 7:40:46 PM)
-        ☐ Add a scene to the tester to test Box2D usage
+        ✔ Add a scene to the tester to test Box2D usage @done (10/28/2021, 2:42:45 PM)
+        ☐ Come up with a way to wrap Box2D into an API
 
     Audio:
 

src/graphics/opengl/defaultShaders.h

@@ -25,7 +25,7 @@ namespace lunarium
 				\
 			void main()\
 			{\
-				gl_Position = projection * vec4(vertex.xy, 0.0, 1.0);\
+				gl_Position = projection * model * vec4(vertex.xy, 0.0, 1.0);\
 			}";
 
 		const char* DefaultShapeFragment = "#version 450 core\n\

src/graphics/opengl/glGraphics.cpp

@@ -194,6 +194,8 @@ namespace lunarium
     {
         mShapeShader.MakeActive();
 		mShapeShader.SetUniformMatrix("projection", 1, glm::value_ptr(mProjection));
+		glm::mat4 model = glm::mat4(1.0f);
+		mShapeShader.SetUniformMatrix("model", 1, glm::value_ptr(model));
 		mShapeShader.SetUniformf("shapeColor", { color.Red, color.Green, color.Blue, color.Alpha });
 		glBindVertexArray(mRectVAO);
 
@@ -220,6 +222,8 @@ namespace lunarium
     {
         mShapeShader.MakeActive();
 		mShapeShader.SetUniformMatrix("projection", 1, glm::value_ptr(mProjection));
+		glm::mat4 model = glm::mat4(1.0f);
+		mShapeShader.SetUniformMatrix("model", 1, glm::value_ptr(model));
 		mShapeShader.SetUniformf("shapeColor", { color.Red, color.Green, color.Blue, color.Alpha });
 		glBindVertexArray(mEllipseVAO);
 
@@ -245,6 +249,8 @@ namespace lunarium
     {
         mShapeShader.MakeActive();
 		mShapeShader.SetUniformMatrix("projection", 1, glm::value_ptr(mProjection));
+		glm::mat4 model = glm::mat4(1.0f);
+		mShapeShader.SetUniformMatrix("model", 1, glm::value_ptr(model));
 		mShapeShader.SetUniformf("shapeColor", { color.Red, color.Green, color.Blue, color.Alpha });
 		glBindVertexArray(mEllipseVAO);
 
@@ -271,6 +277,8 @@ namespace lunarium
     {
         mShapeShader.MakeActive();
 		mShapeShader.SetUniformMatrix("projection", 1, glm::value_ptr(mProjection));
+		glm::mat4 model = glm::mat4(1.0f);
+		mShapeShader.SetUniformMatrix("model", 1, glm::value_ptr(model));
 		mShapeShader.SetUniformf("shapeColor", { color.Red, color.Green, color.Blue, color.Alpha });
 		glBindVertexArray(mRectVAO);
 

src/internal_libs/assets/CMakeLists.txt

@@ -9,4 +9,5 @@ target_include_directories(assets
     PUBLIC ../
     PUBLIC ../../
     PUBLIC ../../../external/glm
+    PUBLIC ../../../external/box2d/include
 )

src/internal_libs/utils/CMakeLists.txt

@@ -4,4 +4,5 @@ add_library(utils stb/stb_image_write.cpp stb/stb_image.cpp args.cpp binaryFileB
 target_include_directories(utils
     PUBLIC "${PROJECT_BINARY_DIR}"
     PUBLIC ../../../external/glm
+    PUBLIC ../../../external/box2d/include
 )

src/internal_libs/utils/types.cpp

@@ -35,6 +35,16 @@ namespace lunarium
         
     }
 
+    Rectangle::Rectangle(b2AABB& box)
+    {
+        float hwidth = box.GetExtents().x;
+        float hheight = box.GetExtents().y;
+        Left = (box.GetCenter().x - hwidth);
+        Top = (box.GetCenter().y - hheight);
+        Width = hwidth * 2;
+        Height = hheight * 2;
+    }
+
     Rectangle::Rectangle(float _left, float _top, float _width, float _height)
         : Left(_left), Top(_top), Width(_width), Height(_height)
     {

src/internal_libs/utils/types.h

@@ -11,6 +11,7 @@
 
 #include <cstdint>
 #include <glm/glm.hpp>
+#include <box2d/box2d.h>
 
 namespace lunarium
 {
@@ -66,7 +67,11 @@ namespace lunarium
 		float right() const { return Left + Width; }
 		float bottom() const { return Top + Height; }
 
+        glm::vec2 LeftTop() const { return glm::vec2(Left, Top); }
+        glm::vec2 RightBottom() const { return glm::vec2(right(), bottom()); }
+
 		Rectangle();
+        Rectangle(b2AABB& box);
 		Rectangle(float _left, float _top, float _width, float _height);
 
 		float Area() const;

src/run_modes/tester/CMakeLists.txt

@@ -1,4 +1,4 @@
-add_library(tester tester.cpp scenes/baseScene.cpp scenes/simpleRenderScene.cpp)
+add_library(tester tester.cpp scenes/baseScene.cpp scenes/simpleRenderScene.cpp scenes/physicsScene.cpp)
 
 target_include_directories(tester
     PUBLIC "${PROJECT_BINARY_DIR}"
@@ -7,4 +7,5 @@ target_include_directories(tester
     PUBLIC ../../../external/glm
     PUBLIC ../../../external/glad/include
     PUBLIC ../../../external/glfw/include
+    PUBLIC ../../../external/box2d/include
 )

src/run_modes/tester/scenes/physicsScene.cpp

@@ -0,0 +1,172 @@
+/******************************************************************************
+*	File		-	physicsScene.h
+*	Author		-	Joey Pollack
+*	Date		-	2021/10/27 (y/m/d)
+*	Mod Date	-	2021/10/27 (y/m/d)
+*	Description	-	Displays a scene that tests the Box2D physics system
+******************************************************************************/
+
+#include "physicsScene.h"
+#include <box2d/box2d.h>
+#include <core/core.h>
+#include <graphics/igraphics.h>
+#include <utils/logger.h>
+
+namespace lunarium
+{
+    PhysicsScene::PhysicsScene(uint32_t logCat)
+        : BaseScene(logCat), mb2World(nullptr)
+    {
+
+    }
+    
+    PhysicsScene::~PhysicsScene()
+    {
+        delete mb2World;
+    }
+
+    void PhysicsScene::OnLoad()
+    {
+        Logger::Log(mLogCat, LogLevel::INFO, "Running Simple Render Test Scene");
+
+        // Comments from the docs: https://box2d.org/documentation/md__d_1__git_hub_box2d_docs_hello.html
+
+        // Every Box2D program begins with the creation of a b2World object. 
+        // b2World is the physics hub that manages memory, objects, and simulation. 
+        // You can allocate the physics world on the stack, heap, or data section.
+
+        // It is easy to create a Box2D world. First, we define the gravity vector.
+        b2Vec2 gravity(0.0f, 10.0f);
+        mb2World = new b2World(gravity);
+
+        /*  CREATING THE GOUND BOX
+            Bodies are built using the following steps:
+
+            1) Define a body with position, damping, etc.
+            2) Use the world object to create the body.
+            3) Define fixtures with a shape, friction, density, etc.
+            4) Create fixtures on the body.
+        */
+
+       // For step 1 we create the ground body. For this we need a body definition. 
+       // With the body definition we specify the initial position of the ground body.
+        b2BodyDef groundBodyDef;
+        groundBodyDef.position.Set(30.0f, 50.0f);
+
+        // For step 2 the body definition is passed to the world object to create the ground body. 
+        // The world object does not keep a reference to the body definition. Bodies are static by default. 
+        // Static bodies don't collide with other static bodies and are immovable.
+        mpGroundBody = mb2World->CreateBody(&groundBodyDef);
+
+        // For step 3 we create a ground polygon. We use the SetAsBox shortcut to form the ground polygon 
+        // into a box shape, with the box centered on the origin of the parent body.
+        // MORE INFO ABOUT SetAsBox() On the web page (see above)
+        mpGroundBox = new b2PolygonShape;
+        mpGroundBox->SetAsBox(20.0f, 5.0f);
+
+        // We finish the ground body in step 4 by creating the shape fixture. For this step we have a shortcut. 
+        // We do not have a need to alter the default fixture material properties, so we can pass the shape directly 
+        // to the body without creating a fixture definition.
+        mpGroundBody->CreateFixture(mpGroundBox, 0.0f);
+
+        /////////////////////////////////////////////////////////////////////////////
+        // So now we have a ground body. We can use the same technique to create a dynamic body. 
+        // The main difference, besides dimensions, is that we must establish the dynamic body's mass properties.
+
+        // First we create the body using CreateBody. By default bodies are static, so we should set the b2BodyType 
+        // at construction time to make the body dynamic.
+        b2BodyDef bodyDef;
+        bodyDef.type = b2_dynamicBody; // Caution: You must set the body type to b2_dynamicBody if you want the body to move in response to forces.
+        bodyDef.position.Set(9.0f, 4.0f);
+        mpDynamicBody = mb2World->CreateBody(&bodyDef);
+
+         
+        // Next we create and attach a polygon shape using a fixture definition. First we create a box shape:
+        mpDynamicBox = new b2PolygonShape;
+        mpDynamicBox->SetAsBox(1.0f, 1.0f);
+
+        // Next we create a fixture definition using the box. Notice that we set density to 1. 
+        // The default density is zero. Also, the friction on the shape is set to 0.3.
+        // Caution: A dynamic body should have at least one fixture with a non-zero density. Otherwise you will get strange behavior. 
+        b2FixtureDef fixtureDef;
+        fixtureDef.shape = mpDynamicBox;
+        fixtureDef.density = 1.0f;
+        fixtureDef.friction = 0.3f;
+
+        // Using the fixture definition we can now create the fixture. This automatically updates the mass of the body. 
+        // You can add as many fixtures as you like to a body. Each one contributes to the total mass.
+        mpDynamicBody->CreateFixture(&fixtureDef);
+    }
+    
+    void PhysicsScene::OnTick(double delta)
+    {
+        // TODO: Implement the "hello world" Box2D example and 
+        //       use a scaling factor of 10 to render it
+        float timeStep = 1.0f / 60.0f;
+        int32 velocityIterations = 6;
+        int32 positionIterations = 2;
+
+        mb2World->Step(timeStep, velocityIterations, positionIterations);
+    }
+    
+    void PhysicsScene::OnRender(IGraphics* g)
+    {
+        // This scaling is a little backwards.
+        // Info about scaling factor:
+        // https://box2d.org/documentation/md__d_1__git_hub_box2d_docs__f_a_q.html#autotoc_md139
+        float scaleFactor = 10.0f;
+
+        b2AABB groundbox;
+        mpGroundBox->ComputeAABB(&groundbox, mpGroundBody->GetTransform(), 0);
+        // float hwidth = groundbox.GetExtents().x;
+        // float hheight = groundbox.GetExtents().y;
+        // float left = (groundbox.GetCenter().x - hwidth);
+        // float top = (groundbox.GetCenter().y - hheight);
+        // float right = left + hwidth * 2;
+        // float bot = top + hheight * 2;
+
+        Rectangle groundRect(groundbox);
+        g->DrawFilledBox(groundRect.LeftTop() * scaleFactor, 
+                        groundRect.RightBottom() * scaleFactor, 
+                        Color(0.0f, 1.0f, 0.0f, 1.0f));
+
+        b2AABB dynbox;
+        mpDynamicBox->ComputeAABB(&dynbox, mpDynamicBody->GetTransform(), 0);
+        Rectangle dynRect(dynbox);
+        g->DrawFilledBox(dynRect.LeftTop() * scaleFactor, 
+                        dynRect.RightBottom() * scaleFactor, 
+                        Color(0.0f, 0.0f, 1.0f, 1.0f));
+
+        // Debug info
+        char str[256] = { 0 };
+        sprintf(str, "GroundBox: (%f, %f) (%f, %f)",
+        groundRect.LeftTop().x * scaleFactor, groundRect.LeftTop().y * scaleFactor,  
+        groundRect.RightBottom().x * scaleFactor, groundRect.RightBottom().y * scaleFactor);
+        g->DrawString(str, Rectangle(10.0f, 10.0f, 800.0f, 30.0f), Color(0.75f, 0.85f, 0.5f, 1.0f), 0.5f);
+
+        sprintf(str, "GroundBox Half Size: (%f, %f)", groundRect.Width, groundRect.Height);
+        g->DrawString(str, Rectangle(10.0f, 35.0f, 800.0f, 30.0f), Color(0.75f, 0.85f, 0.5f, 1.0f), 0.5f);
+        
+        sprintf(str, "DynBox: (%f, %f) (%f, %f)",
+        dynRect.LeftTop().x * scaleFactor, dynRect.LeftTop().y * scaleFactor,  
+        dynRect.RightBottom().x * scaleFactor, dynRect.RightBottom().y * scaleFactor);
+        g->DrawString(str, Rectangle(10.0f, 60.0f, 800.0f, 100.0f), Color(0.75f, 0.85f, 0.5f, 1.0f), 0.5f);
+
+        int ww, wh;
+        Core::MainWindow().GetFramebufferSize(&ww, &wh);
+        for (int i = 0; i < wh; i += 10)
+        {
+            sprintf(str, "%d", i);
+            g->DrawString(str, Rectangle(ww - 35.0f, i, 4.0f, 5.0f), Color(1.0f, 0.0f, 0.0f, 1.0f), 0.25f);
+            g->DrawBox(Rectangle(ww - 10.0f, i, 10.0f, 2.0f), Color(1.0f, 0.0f, 0.0f, 1.0f), 1.0f);
+        }
+
+        for (int i = 0; i < ww; i += 25)
+        {
+            sprintf(str, "%d", i);
+            g->DrawString(str, Rectangle(i, wh - 20.0f, 4.0f, 5.0f), Color(1.0f, 0.0f, 0.0f, 1.0f), 0.25f);
+            g->DrawBox(Rectangle(i, wh - 5.0f, 2.0f, 5.0f), Color(1.0f, 0.0f, 0.0f, 1.0f), 1.0f);
+        }
+    }
+
+}

src/run_modes/tester/scenes/physicsScene.h

@@ -0,0 +1,38 @@
+/******************************************************************************
+*	File		-	physicsScene.h
+*	Author		-	Joey Pollack
+*	Date		-	2021/10/27 (y/m/d)
+*	Mod Date	-	2021/10/27 (y/m/d)
+*	Description	-	Displays a scene that tests the Box2D physics system
+******************************************************************************/
+
+#ifndef PHYSICS_SCENE_H_
+#define PHYSICS_SCENE_H_
+
+#include "baseScene.h"
+
+class b2World;
+class b2Body;
+class b2PolygonShape;
+
+namespace lunarium
+{
+    class PhysicsScene : public BaseScene
+    {
+    public:
+        PhysicsScene(uint32_t logCat);
+        ~PhysicsScene();
+        virtual void OnLoad();
+        virtual void OnTick(double delta);
+        virtual void OnRender(IGraphics* g);
+
+    private:
+        b2World* mb2World;
+        b2Body* mpGroundBody;
+        b2PolygonShape* mpGroundBox;
+        b2Body* mpDynamicBody;
+        b2PolygonShape* mpDynamicBox;
+    };
+}
+
+#endif  // PHYSICS_SCENE_H_

src/run_modes/tester/scenes/simpleRenderScene.cpp

@@ -23,6 +23,7 @@ namespace lunarium
     }
     void SimpleRenderScene::OnLoad()
     {
+        Logger::Log(mLogCat, LogLevel::INFO, "Running Simple Render Test Scene");
         mTextBoxWidth = 500;
 
         // Currently the full default window size

src/run_modes/tester/tester.cpp

@@ -8,6 +8,7 @@
 
 #include "tester.h"
 #include "scenes/simpleRenderScene.h"
+#include "scenes/physicsScene.h"
 
 #include <utils/logger.h>
 #include <graphics/igraphics.h>
@@ -33,8 +34,8 @@ namespace lunarium
         Logger::Log(mLogCat, LogLevel::INFO, "BUILDING WITH THE EDITOR!");
 #endif
 
-    Logger::Log(mLogCat, LogLevel::INFO, "Running Simple Render Test Scene");
+        // mpScene = new SimpleRenderScene(mLogCat);
-    mpScene = new SimpleRenderScene(mLogCat);
+        mpScene = new PhysicsScene(mLogCat);
         mpScene->OnLoad();