Improve Rendering Performance

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

@@ -106,11 +106,13 @@ public class Engine {
                 -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);
+        int[] indices = {
+                0,1,3,
+                3,1,2
+        };
+        RawModel model = loader.loadToVAO(vertices, indices);
         // Run the rendering loop until the user has attempted to close
         // the window or has pressed the ESCAPE key.
         while ( !glfwWindowShouldClose(window) ) {

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

@@ -8,6 +8,7 @@ import org.lwjgl.opengl.GL20;
 import org.lwjgl.opengl.GL30;
 
 import java.nio.FloatBuffer;
+import java.nio.IntBuffer;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -16,11 +17,13 @@ public class Loader {
     private List<Integer> vaos = new ArrayList<>();
     private List<Integer> vbos = new ArrayList<>();
 
-    public RawModel loadToVAO(float[] positions) {
+    public RawModel loadToVAO(float[] positions, int[] indices) {
         int vaoID = createVAO();
+        bindIndicesBuffer(indices);
         storeDataInAttributeList(0, positions);
+
         unbindVAO();
-        return new RawModel(vaoID, positions.length/3);
+        return new RawModel(vaoID, indices.length);
     }
 
     private int createVAO() {
@@ -44,6 +47,22 @@ public class Loader {
         GL30.glBindVertexArray(0);
     }
 
+    private void bindIndicesBuffer(int[] indices) {
+        int vboID = GL15.glGenBuffers();
+        vbos.add(vboID);
+        GL15.glBindBuffer(GL15.GL_ELEMENT_ARRAY_BUFFER, vboID);
+        IntBuffer buffer = storeInIntBuffer(indices);
+        GL15.glBufferData(GL15.GL_ELEMENT_ARRAY_BUFFER, indices, GL15.GL_STATIC_DRAW);
+    }
+
+    private IntBuffer storeInIntBuffer(int[] data) {
+        IntBuffer intBuffer = BufferUtils.createIntBuffer(data.length);
+        intBuffer.put(data);
+        //Buffer is until know expected to be written to. Flip it, so it can be read
+        intBuffer.flip();
+        return intBuffer;
+    }
+
     private FloatBuffer storeInFloatBuffer(float[] data) {
         FloatBuffer floatBuffer = BufferUtils.createFloatBuffer(data.length);
         floatBuffer.put(data);
@@ -52,6 +71,7 @@ public class Loader {
         return floatBuffer;
     }
 
+
     public void cleanUp() {
         for(int vao: vaos) {
             GL30.glDeleteVertexArrays(vao);

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

@@ -8,13 +8,14 @@ import org.lwjgl.opengl.GL30;
 public class Renderer {
 
     public void prepare() {
+        GL11.glClear(GL11.GL_COLOR_BUFFER_BIT);
         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());
+        GL11.glDrawElements(GL11.GL_TRIANGLES, rawModel.getVertexCount(), GL11.GL_UNSIGNED_INT, 0);
         GL20.glDisableVertexAttribArray(0);
         GL30.glBindVertexArray(0);
     }