Render white rectangle

client/src/main/java/core/engine/Engine.java

@@ -1,5 +1,6 @@
 package core.engine;
 
+import core.engine.model.RawModel;
 import org.lwjgl.Version;
 import org.lwjgl.glfw.GLFWErrorCallback;
 import org.lwjgl.glfw.GLFWVidMode;
@@ -19,6 +20,8 @@ import static org.lwjgl.system.MemoryUtil.NULL;
 public class Engine {
 
     private long window;
+    private final Loader loader = new Loader();
+    private final Renderer renderer = new Renderer();
 
     public Engine() {
 
@@ -99,18 +102,29 @@ public class Engine {
 
         // Set the clear color
         glClearColor(1.0f, 0.0f, 0.0f, 0.0f);
-
+        float[] vertices = {
+                -0.5f, 0.5f, 0f,
+                -0.5f, -0.5f, 0f,
+                0.5f, -0.5f, 0f,
+                0.5f, -0.5f, 0f,
+                0.5f, 0.5f, 0f,
+                -0.5f, 0.5f, 0f
+        };
+        RawModel model = loader.loadToVAO(vertices);
         // Run the rendering loop until the user has attempted to close
         // the window or has pressed the ESCAPE key.
         while ( !glfwWindowShouldClose(window) ) {
+            renderer.prepare();
             glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // clear the framebuffer
-
+            renderer.render(model);
             glfwSwapBuffers(window); // swap the color buffers
 
             // Poll for window events. The key callback above will only be
             // invoked during this call.
             glfwPollEvents();
         }
+
+        loader.cleanUp();
     }
 
 }

client/src/main/java/core/engine/Loader.java

@@ -0,0 +1,64 @@
+package core.engine;
+
+import core.engine.model.RawModel;
+import org.lwjgl.BufferUtils;
+import org.lwjgl.opengl.GL11;
+import org.lwjgl.opengl.GL15;
+import org.lwjgl.opengl.GL20;
+import org.lwjgl.opengl.GL30;
+
+import java.nio.FloatBuffer;
+import java.util.ArrayList;
+import java.util.List;
+
+public class Loader {
+
+    private List<Integer> vaos = new ArrayList<>();
+    private List<Integer> vbos = new ArrayList<>();
+
+    public RawModel loadToVAO(float[] positions) {
+        int vaoID = createVAO();
+        storeDataInAttributeList(0, positions);
+        unbindVAO();
+        return new RawModel(vaoID, positions.length/3);
+    }
+
+    private int createVAO() {
+        int vao = GL30.glGenVertexArrays();
+        vaos.add(vao);
+        GL30.glBindVertexArray(vao);
+        return vao;
+    }
+
+    private void storeDataInAttributeList(int attributeNumber, float[] data) {
+        int vboID = GL15.glGenBuffers();
+        vbos.add(vboID);
+        GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, vboID);
+        FloatBuffer floatBuffer = storeInFloatBuffer(data);
+        GL15.glBufferData(GL15.GL_ARRAY_BUFFER, floatBuffer, GL15.GL_STATIC_DRAW);
+        GL20.glVertexAttribPointer(attributeNumber, 3, GL11.GL_FLOAT, false, 0,0);
+        GL15.glBindBuffer(GL15.GL_ARRAY_BUFFER, 0);
+    }
+
+    private void unbindVAO() {
+        GL30.glBindVertexArray(0);
+    }
+
+    private FloatBuffer storeInFloatBuffer(float[] data) {
+        FloatBuffer floatBuffer = BufferUtils.createFloatBuffer(data.length);
+        floatBuffer.put(data);
+        //Buffer is until know expected to be written to. Flip it, so it can be read
+        floatBuffer.flip();
+        return floatBuffer;
+    }
+
+    public void cleanUp() {
+        for(int vao: vaos) {
+            GL30.glDeleteVertexArrays(vao);
+        }
+
+        for(int vbo: vbos) {
+            GL15.glDeleteBuffers(vbo);
+        }
+    }
+}

client/src/main/java/core/engine/Renderer.java

@@ -0,0 +1,21 @@
+package core.engine;
+
+import core.engine.model.RawModel;
+import org.lwjgl.opengl.GL11;
+import org.lwjgl.opengl.GL20;
+import org.lwjgl.opengl.GL30;
+
+public class Renderer {
+
+    public void prepare() {
+        GL11.glClearColor(1,0,0,1);
+    }
+
+    public void render(RawModel rawModel) {
+        GL30.glBindVertexArray(rawModel.getVaoID());
+        GL20.glEnableVertexAttribArray(0);
+        GL11.glDrawArrays(GL11.GL_TRIANGLES, 0, rawModel.getVertexCount());
+        GL20.glDisableVertexAttribArray(0);
+        GL30.glBindVertexArray(0);
+    }
+}

client/src/main/java/core/engine/model/RawModel.java

@@ -0,0 +1,20 @@
+package core.engine.model;
+
+public class RawModel {
+
+    private final int vaoID;
+    private final int vertexCount;
+
+    public RawModel(int vaoID, int vertexCount) {
+        this.vaoID = vaoID;
+        this.vertexCount = vertexCount;
+    }
+
+    public int getVaoID() {
+        return vaoID;
+    }
+
+    public int getVertexCount() {
+        return vertexCount;
+    }
+}