Implement Texture Units, bugfix guessChannelCountAndInternalFormat

This is used as the initial scene that is loaded when the SceneManager
is created.

.gitignore

@@ -4,3 +4,4 @@ target/
 
 .classpath
 .project
+.factorypath

README.md

@@ -0,0 +1,5 @@
+# Epic game
+
+The game does NOTHING still
+
+The setup NEVER ends

assets/shaders/default.frag.glsl

@@ -0,0 +1,8 @@
+#version 330 core
+
+in vec4 fColour;
+out vec4 colour;
+
+void main() {
+  colour = fColour;
+}

assets/shaders/default.vert.glsl

@@ -0,0 +1,11 @@
+#version 330 core
+
+layout (location = 0) in vec3 aPos;
+layout (location = 1) in vec4 aColour;
+
+out vec4 fColour;
+
+void main() {
+  fColour = aColour;
+  gl_Position = vec4(aPos, 1.0);
+}

assets/shaders/fader.frag.glsl

@@ -0,0 +1,10 @@
+#version 330 core
+
+in vec4 fColour;
+out vec4 colour;
+
+uniform float u_alpha;
+
+void main() {
+  colour = vec4(fColour.xyz, 1.0 - u_alpha);
+}

assets/shaders/texture.frag.glsl

@@ -0,0 +1,19 @@
+#version 330 core
+out vec4 FragColour;
+  
+in vec4 ourColour;
+in vec2 TexCoord;
+
+uniform sampler2D texture1;
+uniform sampler2D texture2;
+
+void main()
+{
+  vec4 tex1Color = texture(texture1, TexCoord);
+  vec4 tex2Color = texture(texture2, TexCoord);
+
+  if (tex2Color.a < 0.1)
+    tex2Color = tex1Color;
+
+  FragColour = mix(tex1Color, tex2Color, 0.4f);
+}

assets/shaders/texture.vert.glsl

@@ -0,0 +1,15 @@
+#version 330 core
+
+layout (location = 0) in vec3 aPos;
+layout (location = 1) in vec4 aColour;
+layout (location = 2) in vec2 aTexCoord;
+
+out vec4 ourColour;
+out vec2 TexCoord;
+
+void main()
+{
+  gl_Position = vec4(aPos, 1.0);
+  ourColour = aColour;
+  TexCoord = aTexCoord;
+}

pom.xml

@@ -10,7 +10,6 @@
 
   <name>game</name>
   <description>A simple game.</description>
-  <!-- FIXME change it to the project's website -->
   <url>http://www.hirw.org</url>
 
   <properties>
@@ -35,9 +34,20 @@
 
   <dependencies>
     <dependency>
-      <groupId>junit</groupId>
+      <groupId>org.mockito</groupId>
-      <artifactId>junit</artifactId>
+      <artifactId>mockito-core</artifactId>
-      <version>3.8.1</version>
+      <version>5.19.0</version>
+    </dependency>
+    <dependency>
+      <groupId>org.projectlombok</groupId>
+      <artifactId>lombok</artifactId>
+      <version>1.18.38</version>
+      <scope>provided</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter</artifactId>
+      <version>5.13.4</version>
     </dependency>
     <dependency>
       <groupId>org.lwjgl</groupId>

src/main/java/org/hirw/game/FaderShader.java

@@ -0,0 +1,58 @@
+package org.hirw.game;
+
+import static org.lwjgl.opengl.GL20.*;
+
+import lombok.Getter;
+import lombok.Setter;
+import org.hirw.game.util.Log;
+import org.hirw.game.util.Time;
+
+public class FaderShader extends Shader {
+  private static final String FADER_SHADER_FRAG_PATH = "assets/shaders/fader.frag.glsl";
+  private static final float DEFAULT_ALPHA_INCREASE_STEP = 1.0f / 3;
+  private final float INITIAL_ALPHA = 0.0f;
+
+  @Getter private final float alphaIncreaseStep;
+  @Getter @Setter private float alpha;
+  @Getter @Setter private int alphaUniformLocation;
+
+  public FaderShader(float alphaIncreaseStep) {
+    super(FADER_SHADER_FRAG_PATH, DEFAULT_VERT_PATH);
+    this.alpha = INITIAL_ALPHA;
+    this.alphaIncreaseStep = alphaIncreaseStep;
+  }
+
+  public FaderShader() {
+    this(DEFAULT_ALPHA_INCREASE_STEP);
+  }
+
+  public void init() {
+    super.init();
+    findAlphaUniformLocation();
+  }
+
+  public void update() {
+    super.update();
+    increaseAlpha();
+  }
+
+  private void findAlphaUniformLocation() {
+    int location = glGetUniformLocation(getShaderProgramID(), "u_alpha");
+    if (location == -1) {
+      Log.warning("FaderShader", "Failed to get 'u_alpha' uniform location, trying to continue...");
+    } else {
+      setAlphaUniformLocation(location);
+    }
+  }
+
+  private void increaseAlpha() {
+    if (getAlphaUniformLocation() == -1) return;
+    if (getAlpha() >= 1.0f) return;
+
+    setAlpha(getAlpha() + (getAlphaIncreaseStep() * Time.deltaTime()));
+
+    glUseProgram(getShaderProgramID());
+    glUniform1f(getAlphaUniformLocation(), getAlpha());
+    glUseProgram(0);
+  }
+}

src/main/java/org/hirw/game/Keyboard.java

@@ -0,0 +1,37 @@
+package org.hirw.game;
+
+import static org.lwjgl.glfw.GLFW.*;
+
+import java.util.HashMap;
+
+public class Keyboard {
+  private static Keyboard instance;
+  private HashMap<Integer, Boolean> buttons;
+
+  private Keyboard() {
+    this.buttons = new HashMap<Integer, Boolean>();
+  }
+
+  public static Keyboard getInstance() {
+    if (instance == null) {
+      synchronized (Keyboard.class) {
+        if (instance == null) {
+          instance = new Keyboard();
+        }
+      }
+    }
+    return instance;
+  }
+
+  public static void keyCallback(long window, int keyCode, int _scan, int action, int _modifiers) {
+    if (action == GLFW_PRESS) {
+      getInstance().buttons.put(keyCode, true);
+    } else if (action == GLFW_RELEASE) {
+      getInstance().buttons.put(keyCode, false);
+    }
+  }
+
+  public static boolean isPressed(int keyCode) {
+    return getInstance().buttons.getOrDefault(keyCode, false);
+  }
+}

src/main/java/org/hirw/game/Mesh.java

@@ -0,0 +1,118 @@
+package org.hirw.game;
+
+import static org.lwjgl.opengl.ARBVertexArrayObject.glBindVertexArray;
+import static org.lwjgl.opengl.ARBVertexArrayObject.glGenVertexArrays;
+import static org.lwjgl.opengl.GL20.*;
+
+import java.nio.FloatBuffer;
+import java.nio.IntBuffer;
+import lombok.Getter;
+import lombok.Setter;
+import org.lwjgl.BufferUtils;
+
+public class Mesh {
+  @Getter @Setter private int vaoID, vboID, eboID;
+  @Getter protected Shader shader;
+  @Getter float[] vertices;
+  @Getter int[] elements;
+
+  protected final int POSITION_SIZE = 3;
+  protected final int RGBA_SIZE = 4;
+  protected final int FLOAT_SIZE_IN_BYTES = Float.SIZE / Byte.SIZE;
+
+  protected static final float[] DEFAULT_VERTEX_ARRAY = {
+    0.5f, -0.5f, 0.0f, /*           */ 1.0f, 0.0f, 0.0f, 1.0f,
+    -0.5f, 0.5f, 0.0f, /*           */ 0.0f, 1.0f, 0.0f, 1.0f,
+    0.5f, 0.5f, 0.0f, /*            */ 0.0f, 0.0f, 1.0f, 1.0f,
+    -0.5f, -0.5f, 0.0f, /*          */ 1.0f, 1.0f, 0.0f, 1.0f,
+  };
+
+  protected static final int[] DEFAULT_ELEMENT_ARRAY = {
+    2, 1, 0,
+    0, 1, 3
+  };
+
+  public Mesh(Shader shader, float[] vertexArray, int[] elementArray) {
+    this.shader = shader;
+    this.vaoID = -1;
+    this.vboID = -1;
+    this.eboID = -1;
+    this.vertices = vertexArray;
+    this.elements = elementArray;
+  }
+
+  public Mesh(Shader shader) {
+    this(shader, DEFAULT_VERTEX_ARRAY, DEFAULT_ELEMENT_ARRAY);
+  }
+
+  public void init() {
+    initialiseVertexArrayObject();
+  }
+
+  public void draw() {
+    getShader().use();
+    glDraw();
+    getShader().detach();
+  }
+
+  public void log() {
+    System.out.println(this.toString());
+  }
+
+  public String toString() {
+    return String.format(
+        "VAO: %d, VBO: %d, EBO: %d, ShaderProgram: %d",
+        getEboID(), getVboID(), getEboID(), getShader().getShaderProgramID());
+  }
+
+  protected void glDraw() {
+    glBindVertexArray(this.vaoID);
+    glDrawElements(GL_TRIANGLES, getElements().length, GL_UNSIGNED_INT, 0);
+    glBindVertexArray(0);
+  }
+
+  private void initialiseVertexArrayObject() {
+    setVaoID(glGenVertexArrays());
+    glBindVertexArray(getVaoID());
+
+    initialiseVertexBufferObject();
+    initialiseElementBufferObject();
+
+    initialiseAttribPointers();
+  }
+
+  protected int initialiseAttribPointers() {
+    int vertexSizeInBytes = calculateVertexSizeInBytes();
+
+    glVertexAttribPointer(0, POSITION_SIZE, GL_FLOAT, false, vertexSizeInBytes, 0);
+    glEnableVertexAttribArray(0);
+
+    glVertexAttribPointer(
+        1, RGBA_SIZE, GL_FLOAT, false, vertexSizeInBytes, POSITION_SIZE * FLOAT_SIZE_IN_BYTES);
+    glEnableVertexAttribArray(1);
+
+    return vertexSizeInBytes;
+  }
+
+  protected int calculateVertexSizeInBytes() {
+    return (POSITION_SIZE + RGBA_SIZE) * FLOAT_SIZE_IN_BYTES;
+  }
+
+  private void initialiseVertexBufferObject() {
+    FloatBuffer vertexBuffer = BufferUtils.createFloatBuffer(getVertices().length);
+    vertexBuffer.put(getVertices()).flip();
+
+    setVboID(glGenBuffers());
+    glBindBuffer(GL_ARRAY_BUFFER, getVboID());
+    glBufferData(GL_ARRAY_BUFFER, vertexBuffer, GL_STATIC_DRAW);
+  }
+
+  private void initialiseElementBufferObject() {
+    IntBuffer elementBuffer = BufferUtils.createIntBuffer(getElements().length);
+    elementBuffer.put(getElements()).flip();
+
+    setEboID(glGenBuffers());
+    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, getEboID());
+    glBufferData(GL_ELEMENT_ARRAY_BUFFER, elementBuffer, GL_STATIC_DRAW);
+  }
+}

src/main/java/org/hirw/game/Mouse.java

@@ -0,0 +1,67 @@
+package org.hirw.game;
+
+import static org.lwjgl.glfw.GLFW.*;
+
+import java.util.HashMap;
+
+public class Mouse {
+  private double x, y, oldX, oldY;
+  private HashMap<Integer, Boolean> buttons;
+
+  private static Mouse instance;
+
+  public interface Buttons {
+    public final int LEFT = GLFW_MOUSE_BUTTON_LEFT;
+    public final int RIGHT = GLFW_MOUSE_BUTTON_RIGHT;
+  }
+
+  private Mouse() {
+    this.buttons = new HashMap<Integer, Boolean>();
+  }
+
+  public static Mouse getInstance() {
+    if (instance == null) {
+      synchronized (Mouse.class) { // Double checked locking
+        if (instance == null) {
+          instance = new Mouse();
+        }
+      }
+    }
+    return instance;
+  }
+
+  public static void cursorPositionCallback(long window, double newX, double newY) {
+    getInstance().oldX = getInstance().x;
+    getInstance().oldY = getInstance().y;
+    getInstance().x = newX;
+    getInstance().y = newY;
+  }
+
+  public static void mouseButtonCallback(long window, int keyCode, int action, int _modifiers) {
+    if (action == GLFW_PRESS) {
+      getInstance().buttons.put(keyCode, true);
+    } else if (action == GLFW_RELEASE) {
+      getInstance().buttons.put(keyCode, false);
+    }
+  }
+
+  public static double getX() {
+    return getInstance().x;
+  }
+
+  public static double getY() {
+    return getInstance().y;
+  }
+
+  public static double getDeltaX() {
+    return getInstance().oldX - getInstance().x;
+  }
+
+  public static double getDeltaY() {
+    return getInstance().oldY - getInstance().y;
+  }
+
+  public static boolean isPressed(int keyCode) {
+    return getInstance().buttons.getOrDefault(keyCode, false);
+  }
+}

src/main/java/org/hirw/game/Scene.java

@@ -0,0 +1,19 @@
+package org.hirw.game;
+
+import lombok.Getter;
+
+public abstract class Scene {
+  @Getter private final SceneType sceneType;
+
+  public Scene(SceneType sceneType) {
+    this.sceneType = sceneType;
+  }
+
+  public abstract void init();
+
+  public abstract void update();
+
+  public String toString() {
+    return getSceneType().toString();
+  }
+}

src/main/java/org/hirw/game/SceneManager.java

@@ -0,0 +1,56 @@
+package org.hirw.game;
+
+import java.util.EnumMap;
+import java.util.Map;
+import lombok.Getter;
+import org.hirw.game.util.Log;
+
+public final class SceneManager {
+  private static final SceneType DEFAULT_SCENE_TYPE = SceneType.SPLASH;
+
+  private static final EnumMap<SceneType, Scene> SCENES =
+      new EnumMap<>(
+          Map.of(
+              SceneType.SPLASH, new SplashScene(),
+              SceneType.MENU, new SplashScene(),
+              SceneType.GAME, new SplashScene()));
+
+  @Getter private static Scene scene;
+
+  public static void init() {
+    setScene(DEFAULT_SCENE_TYPE);
+  }
+
+  public static void setScene(SceneType sceneType) {
+    Scene newScene = SCENES.get(sceneType);
+
+    if (scene == newScene) {
+      Log.warning("SceneManager", sameSceneWarningString());
+      return;
+    } else {
+      scene = newScene;
+    }
+
+    scene.init();
+    logSceneChange();
+  }
+
+  public static void update() {
+    if (scene.getSceneType() == null) return;
+
+    getScene().update();
+  }
+
+  private static void logSceneChange() {
+    SceneType newSceneType = getScene().getSceneType();
+    String loadedSceneMessage = String.format("Changed to scene '%s'", newSceneType.toString());
+
+    Log.success("SceneManager", loadedSceneMessage);
+  }
+
+  private static String sameSceneWarningString() {
+    return String.format(
+        "Tried to switch to scene '%s' but that scene is already loaded",
+        scene.getSceneType().toString());
+  }
+}

src/main/java/org/hirw/game/SceneType.java

@@ -0,0 +1,7 @@
+package org.hirw.game;
+
+public enum SceneType {
+  SPLASH,
+  MENU,
+  GAME,
+}

src/main/java/org/hirw/game/Shader.java

@@ -0,0 +1,128 @@
+package org.hirw.game;
+
+import static org.lwjgl.opengl.GL20.*;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.InvalidPathException;
+import java.nio.file.NoSuchFileException;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.EnumMap;
+import java.util.Map;
+import lombok.Getter;
+import lombok.Setter;
+import org.hirw.game.util.Log;
+
+public class Shader {
+  private enum ShaderType {
+    FRAG,
+    VERT
+  }
+
+  private static final EnumMap<ShaderType, Integer> SHADERS =
+      new EnumMap<>(
+          Map.of(
+              ShaderType.FRAG, GL_FRAGMENT_SHADER,
+              ShaderType.VERT, GL_VERTEX_SHADER));
+
+  protected static final String DEFAULT_FRAG_PATH = "assets/shaders/default.frag.glsl";
+  protected static final String DEFAULT_VERT_PATH = "assets/shaders/default.vert.glsl";
+
+  @Getter private String vertexSource;
+  @Getter private String fragmentSource;
+  @Getter @Setter private int vertexID;
+  @Getter @Setter private int fragmentID;
+  @Getter @Setter private int shaderProgramID;
+
+  public Shader(String fragPath, String vertPath) {
+    this.fragmentSource = readFromFile(fragPath);
+    this.vertexSource = readFromFile(vertPath);
+  }
+
+  public Shader(String path) {
+    this(path + ".frag.glsl", path + ".vert.glsl");
+  }
+
+  public Shader() {
+    this(DEFAULT_FRAG_PATH, DEFAULT_VERT_PATH);
+  }
+
+  public void init() {
+    compileShader(ShaderType.FRAG);
+    compileShader(ShaderType.VERT);
+    createProgram();
+  }
+
+  public void use() {
+    glUseProgram(getShaderProgramID());
+  }
+
+  public void detach() {
+    glUseProgram(0);
+  }
+
+  public void update() {}
+
+  private void compileShader(ShaderType shaderType) {
+    int shaderID = glCreateShader(SHADERS.get(shaderType));
+
+    switch (shaderType) {
+      case ShaderType.FRAG -> {
+        setFragmentID(shaderID);
+        glShaderSource(shaderID, getFragmentSource());
+      }
+      case ShaderType.VERT -> {
+        setVertexID(shaderID);
+        glShaderSource(shaderID, getVertexSource());
+      }
+    }
+
+    glCompileShader(shaderID);
+
+    if (glGetShaderi(shaderID, GL_COMPILE_STATUS) == GL_FALSE) {
+      int len = glGetShaderi(shaderID, GL_INFO_LOG_LENGTH);
+      Log.error(
+          "Shader",
+          String.format(
+              "Failed to compile %s shader: %s",
+              shaderType.toString(), glGetShaderInfoLog(shaderID, len)));
+    }
+  }
+
+  private void createProgram() {
+    int id = glCreateProgram();
+    glAttachShader(id, getVertexID());
+    glAttachShader(id, getFragmentID());
+    glLinkProgram(id);
+
+    int success = glGetProgrami(id, GL_LINK_STATUS);
+    if (success == GL_FALSE) {
+      int len = glGetProgrami(id, GL_INFO_LOG_LENGTH);
+
+      Log.error(
+          "Shader",
+          String.format("Failed to create Shader Program: %s", glGetShaderInfoLog(id, len)));
+    } else {
+      Log.success("Shader", "Shader Program created.");
+    }
+
+    setShaderProgramID(id);
+  }
+
+  private String readFromFile(String stringFilePath) {
+    String source = "";
+
+    try {
+      Path filePath = Paths.get(stringFilePath);
+      source = Files.readString(filePath);
+
+    } catch (NoSuchFileException | InvalidPathException e) {
+      Log.error("Shader", "Couldn't open file (probably a bad path): " + stringFilePath);
+    } catch (IOException e) {
+      Log.error("Shader", "An IO Exception occured while reading from file: " + stringFilePath);
+    }
+
+    return source;
+  }
+}

src/main/java/org/hirw/game/SplashScene.java

@@ -0,0 +1,72 @@
+package org.hirw.game;
+
+import lombok.Getter;
+import lombok.Setter;
+
+public class SplashScene extends Scene {
+  @Getter public final SceneType SCENE_TYPE = SceneType.SPLASH;
+
+  @Getter @Setter private Mesh screenCover;
+  @Getter @Setter private FaderShader screenCoverFaderShader;
+  @Getter @Setter private Mesh logo;
+
+  public SplashScene() {
+    super(SceneType.SPLASH);
+  }
+
+  public void init() {
+    createScreenCover();
+    createLogo();
+  }
+
+  public void update() {
+    getLogo().draw();
+    getScreenCoverFaderShader().update();
+    getScreenCover().draw();
+  }
+
+  private void createScreenCover() {
+    FaderShader faderShader = new FaderShader();
+    faderShader.init();
+    Mesh screenCover = new Mesh(faderShader, screenCoverRectVertices, screenCoverRectElements);
+    screenCover.init();
+    setScreenCoverFaderShader(faderShader);
+    setScreenCover(screenCover);
+  }
+
+  private void createLogo() {
+    Shader texturedShader = new Shader("assets/shaders/texture");
+    texturedShader.init();
+    Texture logoTexture = new Texture(225, 225, "assets/textures/plink.png");
+    Texture flameTexture = new Texture(2500, 2500, "assets/textures/flames.png");
+    logoTexture.init();
+    flameTexture.init();
+    Mesh logoMesh =
+        new TexturedMesh(
+            texturedShader,
+            new Texture[] {logoTexture, flameTexture},
+            logoRectVertices,
+            screenCoverRectElements);
+    logoMesh.init();
+    setLogo(logoMesh);
+  }
+
+  private static final float[] screenCoverRectVertices = {
+    1.0f, 1.0f, 0.0f, /*            */ 0.0f, 0.0f, 0.0f, 0.0f, // 0 Top Right
+    1.0f, -1.0f, 0.0f, /*           */ 0.0f, 0.0f, 0.0f, 0.0f, // 1 Bottom Right
+    -1.0f, -1.0f, 0.0f, /*          */ 0.0f, 0.0f, 0.0f, 0.0f, // 2 Bottom Left
+    -1.0f, 1.0f, 0.0f, /*           */ 0.0f, 0.0f, 0.0f, 0.0f, // 3 Top Left
+  };
+
+  private static final int[] screenCoverRectElements = {
+    0, 1, 3,
+    1, 2, 3
+  };
+
+  private static final float[] logoRectVertices = {
+    0.1f, 0.1f, 0.0f, /*       */ 0.0f, 0.0f, 0.0f, 0.0f, /*    */ 1.0f, 1.0f, //   0 Top Right
+    0.1f, -0.1f, 0.0f, /*      */ 0.0f, 0.0f, 0.0f, 0.0f, /*    */ 1.0f, 0.0f, //  1 Bottom Right
+    -0.1f, -0.1f, 0.0f, /*     */ 0.0f, 0.0f, 0.0f, 0.0f, /*    */ 0.0f, 0.0f, // 2 Bottom Left
+    -0.1f, 0.1f, 0.0f, /*      */ 0.0f, 0.0f, 0.0f, 0.0f, /*    */ 0.0f, 1.0f, //  3 Top Left
+  };
+}

src/main/java/org/hirw/game/Texture.java

@@ -0,0 +1,105 @@
+package org.hirw.game;
+
+import static org.lwjgl.opengl.GL11.*;
+import static org.lwjgl.opengl.GL12.*;
+import static org.lwjgl.stb.STBImage.stbi_image_free;
+import static org.lwjgl.stb.STBImage.stbi_load;
+import static org.lwjgl.stb.STBImage.stbi_set_flip_vertically_on_load;
+
+import java.nio.ByteBuffer;
+import lombok.Getter;
+import lombok.Setter;
+
+public class Texture {
+  @Getter private int width;
+  @Getter private int height;
+  @Getter private String texturePath;
+  @Getter @Setter private int textureID;
+  @Getter @Setter private int channelCount;
+  @Getter @Setter private int internalFormat;
+
+  public Texture(int width, int height, String texturePath) {
+    this.width = width;
+    this.height = height;
+    this.texturePath = texturePath;
+    guessChannelCountAndInternalFormat();
+  }
+
+  private void guessChannelCountAndInternalFormat() {
+    int fileExtensionIndex = getTexturePath().lastIndexOf(".");
+    if (fileExtensionIndex == -1) {
+      // No file extension, so just assume 4 channels (.png -> RGBA)
+      setChannelCount(4);
+      setInternalFormat(GL_RGBA);
+      return;
+    }
+
+    String fileExtension = getTexturePath().substring(fileExtensionIndex + 1);
+    switch (fileExtension) {
+      case "png":
+        setChannelCount(4);
+        setInternalFormat(GL_RGBA);
+        break;
+      case "jpg":
+        setChannelCount(3);
+        setInternalFormat(GL_RGB);
+        break;
+      default:
+        // just pray at this point
+        setChannelCount(3);
+        setInternalFormat(GL_RGB);
+    }
+  }
+
+  public void init() {
+    ByteBuffer imageBytes = loadImageBytes();
+    createTexture(imageBytes);
+    stbi_image_free(imageBytes);
+  }
+
+  private ByteBuffer loadImageBytes() {
+    stbi_set_flip_vertically_on_load(true);
+    return stbi_load(
+        getTexturePath(),
+        new int[getWidth()],
+        new int[getHeight()],
+        new int[getChannelCount()],
+        getChannelCount());
+  }
+
+  private void createTexture(ByteBuffer imageBytes) {
+    setTextureID(glGenTextures());
+    glBindTexture(GL_TEXTURE_2D, getTextureID());
+    glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+
+    setupFilterParameters();
+    setupWrapParameters();
+
+    glTexImage2D(
+        GL_TEXTURE_2D,
+        0,
+        getInternalFormat(),
+        getWidth(),
+        getHeight(),
+        0,
+        getInternalFormat(),
+        GL_UNSIGNED_BYTE,
+        imageBytes);
+    // glGenerateMipmap(GL_TEXTURE_2D);
+  }
+
+  private void setupFilterParameters() {
+    // https://github.com/mattdesl/lwjgl-basics/wiki/textures#texture-parameters
+    // Set the minification and Magnifiation filters:
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+  }
+
+  private void setupWrapParameters() {
+    // https://github.com/mattdesl/lwjgl-basics/wiki/textures#texture-parameters
+    // Each Vertex has many attributes, including Position (x, y) and Texture Coordinates (s, t).
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+  }
+}

src/main/java/org/hirw/game/TexturedMesh.java

@@ -0,0 +1,47 @@
+package org.hirw.game;
+
+import static org.lwjgl.opengl.GL11.*;
+import static org.lwjgl.opengl.GL20.*;
+
+import lombok.Getter;
+
+public class TexturedMesh extends Mesh {
+  @Getter private Texture[] textures;
+
+  private final int TEXTURE_COORDS_SIZE = 2;
+
+  public TexturedMesh(Shader shader, Texture[] textures, float[] vertexArray, int[] elementArray) {
+    super(shader, vertexArray, elementArray);
+    this.textures = textures;
+  }
+
+  public TexturedMesh(Shader shader, Texture[] textures) {
+    this(shader, textures, DEFAULT_VERTEX_ARRAY, DEFAULT_ELEMENT_ARRAY);
+  }
+
+  protected int initialiseAttribPointers() {
+    int vertexSizeInBytes = super.initialiseAttribPointers();
+
+    int offset = (POSITION_SIZE + RGBA_SIZE) * FLOAT_SIZE_IN_BYTES;
+    glVertexAttribPointer(2, TEXTURE_COORDS_SIZE, GL_FLOAT, false, vertexSizeInBytes, offset);
+    glEnableVertexAttribArray(2);
+
+    return vertexSizeInBytes;
+  }
+
+  protected int calculateVertexSizeInBytes() {
+    return (POSITION_SIZE + RGBA_SIZE + TEXTURE_COORDS_SIZE) * FLOAT_SIZE_IN_BYTES;
+  }
+
+  protected void glDraw() {
+    for (int i = 0; i < textures.length; i++) {
+      int textureUnitIndexStart = GL_TEXTURE0;
+      int textureUnitIndex = textureUnitIndexStart + i;
+      glActiveTexture(textureUnitIndex);
+      glBindTexture(GL_TEXTURE_2D, getTextures()[i].getTextureID());
+      String uniformName = "texture" + Integer.toString(i + 1);
+      glUniform1i(glGetUniformLocation(getShader().getShaderProgramID(), uniformName), i);
+    }
+    super.glDraw();
+  }
+}

src/main/java/org/hirw/game/Window.java

@@ -3,22 +3,25 @@ package org.hirw.game;
 import static org.lwjgl.glfw.Callbacks.*;
 import static org.lwjgl.glfw.GLFW.*;
 import static org.lwjgl.opengl.GL11.*;
-import static org.lwjgl.system.MemoryStack.*;
 import static org.lwjgl.system.MemoryUtil.*;
 
-import java.nio.*;
+import lombok.Getter;
+import lombok.Setter;
+import org.hirw.game.util.Time;
 import org.lwjgl.Version;
 import org.lwjgl.glfw.*;
 import org.lwjgl.opengl.*;
-import org.lwjgl.system.*;
 
 public class Window {
   private int width, height;
-  private final String title;
+  @Getter private String title;
-  private long glfwWindow;
+  @Getter private long glfwWindow;
 
   private static Window window = null;
 
+  @Getter @Setter private Shader shader;
+  @Getter @Setter private Mesh mesh;
+
   private Window() {
     this.width = 1280;
     this.height = 720;
@@ -26,25 +29,31 @@ public class Window {
   }
 
   public static Window get() {
-    if (Window.window == null) {
+    if (window == null) {
-      Window.window = new Window();
+      window = new Window();
     }
-
+    return window;
-    return Window.window;
   }
 
   public void blastOff() {
-    logVersion();
+    init();
-    setup();
     loop();
     cleanUp();
   }
 
+  private void init() {
+    logVersion();
+    createWindow();
+    createShader();
+    createMesh();
+    SceneManager.init();
+  }
+
   private void logVersion() {
     System.out.println("LWJGL Version: " + Version.getVersion());
   }
 
-  private void setup() {
+  private void createWindow() {
     GLFWErrorCallback.createPrint(System.err).set();
     if (!glfwInit()) throw new IllegalStateException("Unable to initialize GLFW");
 
@@ -52,36 +61,46 @@ public class Window {
     glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);
     glfwWindowHint(GLFW_RESIZABLE, GLFW_TRUE);
 
-    glfwWindow = glfwCreateWindow(this.width, this.height, "Hello World!", NULL, NULL);
+    glfwWindow = glfwCreateWindow(this.width, this.height, getTitle(), NULL, NULL);
     if (glfwWindow == NULL) throw new RuntimeException("Failed to create the GLFW window");
 
-    // glfwSetKeyCallback(
+    glfwSetCursorPosCallback(glfwWindow, Mouse::cursorPositionCallback);
-    //     glfwWindow,
+    glfwSetMouseButtonCallback(glfwWindow, Mouse::mouseButtonCallback);
-    //     (glfwWindow, key, scancode, action, mods) -> {
+    glfwSetKeyCallback(glfwWindow, Keyboard::keyCallback);
-    //       if (key == GLFW_KEY_ESCAPE && action == GLFW_RELEASE)
-    //         glfwSetWindowShouldClose(glfwWindow, true);
-    //     });
-    //
-    // try (MemoryStack stack = stackPush()) {
-    //   IntBuffer pWidth = stack.mallocInt(1);
-    //   IntBuffer pHeight = stack.mallocInt(1);
-    //   glfwGetWindowSize(glfwWindow, pWidth, pHeight);
-    //   GLFWVidMode vidmode = glfwGetVideoMode(glfwGetPrimaryMonitor());
-    // }
 
     glfwSetWindowTitle(glfwWindow, this.title);
     glfwMakeContextCurrent(glfwWindow);
     glfwSwapInterval(1);
     glfwShowWindow(glfwWindow);
+
     GL.createCapabilities();
+
+    glEnable(GL_BLEND);
+    glEnable(GL_TEXTURE_2D);
+
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
+    glClearColor(1.0f, 1.0f, 1.0f, 0.0f);
+  }
+
+  private void createShader() {
+    Shader shader = new Shader();
+    setShader(shader);
+    shader.init();
+  }
+
+  private void createMesh() {
+    Mesh mesh = new Mesh(getShader());
+    setMesh(mesh);
+    mesh.init();
   }
 
   private void loop() {
-    // GL.createCapabilities(); // Does this maybe go in here?
-    glClearColor(1.0f, 0.0f, 0.0f, 0.0f);
-
     while (!glfwWindowShouldClose(glfwWindow)) {
+      Time.update();
       glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+      getMesh().draw();
+      SceneManager.update();
       glfwSwapBuffers(glfwWindow);
       glfwPollEvents();
     }

src/main/java/org/hirw/game/util/Log.java

@@ -0,0 +1,68 @@
+package org.hirw.game.util;
+
+import java.util.EnumMap;
+import java.util.Map;
+
+public final class Log {
+  private interface Colours {
+    final String BLACK = "\u001B[30m";
+    final String BLACK_BG = "\u001B[40m";
+    final String RED = "\u001B[31m";
+    final String RED_BG = "\u001B[41m";
+    final String GREEN = "\u001B[32m";
+    final String GREEN_BG = "\u001B[42m";
+    final String YELLOW = "\u001B[33m";
+    final String YELLOW_BG = "\u001B[43m";
+    final String BLUE = "\u001B[34m";
+    final String BLUE_BG = "\u001B[44m";
+    final String PURPLE = "\u001B[35m";
+    final String PURPLE_BG = "\u001B[45m";
+    final String CYAN = "\u001B[36m";
+    final String CYAN_BG = "\u001B[46m";
+    final String WHITE = "\u001B[37m";
+    final String WHITE_BG = "\u001B[47m";
+    final String ANSI_RESET = "\u001B[0m";
+  }
+
+  private static final EnumMap<LogType, String> COLOUR_FROM_LOG_TYPE =
+      new EnumMap<>(
+          Map.of(
+              LogType.SUCCESS, Colours.GREEN,
+              LogType.ERROR, Colours.RED,
+              LogType.WARNING, Colours.PURPLE,
+              LogType.DEBUG, Colours.WHITE));
+
+  public static void error(String errorStage, String errorDescription) {
+    System.out.println(formatString(LogType.ERROR, errorStage, errorDescription));
+  }
+
+  public static void success(String successStage, String successDescription) {
+    System.out.println(formatString(LogType.SUCCESS, successStage, successDescription));
+  }
+
+  public static void warning(String warningStage, String warningDescription) {
+    System.out.println(formatString(LogType.WARNING, warningStage, warningDescription));
+  }
+
+  public static void debug(String debugMessage) {
+    System.out.println(formatString(LogType.DEBUG, "DEBUG", debugMessage));
+  }
+
+  private static String formatString(LogType logType, String stage, String description) {
+    String formattedType = String.format("[%s]", colouriseString(logType, logType.toString()));
+    String formattedStage = colouriseString(Colours.YELLOW, String.format("<%s>", stage));
+    return String.format("%s %s %s", formattedType, formattedStage, description);
+  }
+
+  private static String colouriseString(LogType logType, String string) {
+    return COLOUR_FROM_LOG_TYPE.get(logType) + string + Colours.ANSI_RESET;
+  }
+
+  private static String colouriseString(String colour, String string) {
+    return colour + string + Colours.ANSI_RESET;
+  }
+
+  private static String colouriseString(String colour, String otherColour, String string) {
+    return colour + otherColour + string + Colours.ANSI_RESET;
+  }
+}

src/main/java/org/hirw/game/util/LogType.java

@@ -0,0 +1,8 @@
+package org.hirw.game.util;
+
+public enum LogType {
+  SUCCESS,
+  WARNING,
+  ERROR,
+  DEBUG,
+}

src/main/java/org/hirw/game/util/Time.java

@@ -0,0 +1,31 @@
+package org.hirw.game.util;
+
+public final class Time {
+  private static long lastTime = NanoTimer.system().nanoTime();
+  private static long currentTime = NanoTimer.system().nanoTime();
+  private static NanoTimer nanoTimer = NanoTimer.system();
+
+  public interface NanoTimer {
+    long nanoTime();
+
+    static NanoTimer system() {
+      return System::nanoTime;
+    }
+  }
+
+  static void setNanoTimer(NanoTimer timer) {
+    nanoTimer = timer;
+    lastTime = nanoTimer.nanoTime();
+    currentTime = nanoTimer.nanoTime();
+  }
+
+  public static void update() {
+    lastTime = currentTime;
+    currentTime = nanoTimer.nanoTime();
+  }
+
+  public static float deltaTime() {
+    final float ONE_SECOND = 1_000_000_000f;
+    return (currentTime - lastTime) / ONE_SECOND;
+  }
+}

src/test/java/org/hirw/game/AppTest.java

@@ -1,38 +0,0 @@
-package org.hirw.game;
-
-import junit.framework.Test;
-import junit.framework.TestCase;
-import junit.framework.TestSuite;
-
-/**
- * Unit test for simple App.
- */
-public class AppTest
-    extends TestCase
-{
-    /**
-     * Create the test case
-     *
-     * @param testName name of the test case
-     */
-    public AppTest( String testName )
-    {
-        super( testName );
-    }
-
-    /**
-     * @return the suite of tests being tested
-     */
-    public static Test suite()
-    {
-        return new TestSuite( AppTest.class );
-    }
-
-    /**
-     * Rigourous Test :-)
-     */
-    public void testApp()
-    {
-        assertTrue( true );
-    }
-}

src/test/java/org/hirw/game/util/TimeTest.java

@@ -0,0 +1,64 @@
+package org.hirw.game.util;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.Mockito.when;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+
+class TimeTest {
+  final float ONE_SECOND = 1_000_000_000f;
+  final long ONE_MILLISECOND = 1_000_000L;
+  final float MOE = 0.00000001f; // Margin of error
+
+  private Time.NanoTimer nanoTimer;
+
+  @BeforeEach
+  void setUp() {
+    nanoTimer = Mockito.mock(Time.NanoTimer.class);
+    when(nanoTimer.nanoTime()).thenReturn(0L);
+    Time.setNanoTimer(nanoTimer);
+  }
+
+  @Test
+  void testDeltaTimeInitialState() {
+    float deltaTime = Time.deltaTime();
+    assertEquals(deltaTime, 0f, MOE, "should be 0");
+  }
+
+  @Test
+  void testDeltaTimeAfterUpdate() {
+    when(nanoTimer.nanoTime()).thenReturn(ONE_MILLISECOND);
+
+    Time.update();
+    float deltaTime = Time.deltaTime();
+
+    assertEquals(deltaTime, ONE_MILLISECOND / ONE_SECOND, MOE, "should reflect time difference");
+  }
+
+  @Test
+  void testMultipleUpdates() {
+    when(nanoTimer.nanoTime()).thenReturn(ONE_MILLISECOND).thenReturn(ONE_MILLISECOND * 4);
+
+    Time.update();
+    float delta1 = Time.deltaTime();
+
+    Time.update();
+    float delta2 = Time.deltaTime();
+
+    assertEquals(delta1, ONE_MILLISECOND / ONE_SECOND, MOE, "should be 1/1000th second");
+    assertEquals(delta2, (ONE_MILLISECOND * 3) / ONE_SECOND, MOE, "should be 3/1000th second");
+  }
+
+  @Test
+  void testConsistentStateAcrossCalls() {
+    when(nanoTimer.nanoTime()).thenReturn(ONE_MILLISECOND);
+
+    Time.update();
+    float delta1 = Time.deltaTime();
+    float delta2 = Time.deltaTime();
+
+    assertEquals(delta1, delta2, MOE, "should be equal delta time");
+  }
+}