Persistent buffers v1.5

- Add new sync function to GlBuffer

src/main/java/com/jozufozu/flywheel/backend/gl/buffer/GlBuffer.java

@@ -27,6 +27,10 @@ public abstract class GlBuffer extends GlObject {
 		GL20.glBindBuffer(type.glEnum, 0);
 	}
 
+	public void doneForThisFrame() {
+
+	}
+
 	public abstract void alloc(long size);
 
 	public abstract void upload(ByteBuffer directBuffer);

src/main/java/com/jozufozu/flywheel/backend/gl/buffer/PersistentGlBuffer.java

@@ -20,9 +20,7 @@ public class PersistentGlBuffer extends GlBuffer {
 	}
 
 	@Override
-	public void unbind() {
+	public void doneForThisFrame() {
-		super.unbind();
-
 		fence = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);
 	}
 

src/main/java/com/jozufozu/flywheel/backend/instancing/Instancer.java

@@ -90,6 +90,9 @@ public class Instancer<D extends InstanceData> {
 
 		if (glInstanceCount > 0) model.drawInstances(glInstanceCount);
 
+		// persistent mapping sync point
+		instanceVBO.doneForThisFrame();
+
 		vao.unbind();
 	}