- Moved OpenGL library wrapper into platform

- Finished reorganizing PLANNING.md

planning/2D_GRAPHICS.md

@@ -0,0 +1,64 @@
+
+# 2D Graphics (`gfx2d`)
+
+## Table of Contents
+
+<!-- TOC -->
+* [Home](./CONTENTS.md#planning-documentation-for-fennec)
+* [2D Graphics (`gfx2d`)](#2d-graphics-gfx2d)
+  * [Table of Contents](#table-of-contents)
+  * [Introduction](#introduction)
+    * [Structures (`gfx2d`)](#structures-gfx2d)
+<!-- TOC -->
+
+
+## Introduction
+
+&ensp; This system handles the rendering of 2D meshes and textures.
+
+Links:
+- https://en.wikipedia.org/wiki/Quadtree
+- https://developer.nvidia.com/gpugems/gpugems3/part-iv-image-effects/chapter-25-rendering-vector-art-gpu
+
+
+### Structures (`gfx2d`)
+
+For the 2d rendering framework, Materials need to be rendered independently because we have  
+no size constraints for images. This disallows us from using a meta-shader like in  
+the 3d rendering framework.
+
+```c++
+struct Object
+{
+    vec2 location, scale; // A matrix would be 36 bytes, this is instead 20 bytes
+    float rotation;
+}
+```
+
+- BVH
+    - Quadtree
+        - Leaf Size and Tree Depth should be calculated by the scene, constraints are as follows:
+            - Min Object Size
+            - Max Object Size
+            - Scene Center
+            - Scene Edge
+        - Insertions and Updates are done on the CPU
+        - Nodes
+            - Start Index 32-bits
+            - Object Count 32-bits
+        - Objects
+            - Buffer of Object IDs grouped by Octree Node
+    - Culling
+        - Starting at each Octree Leaf, traverse upwards.
+        - Insert Visible Leaf IDs
+            - Track using atomic buffer
+    - Generate the Command Buffer for Culled Meshes from the Visible Leaf Buffer
+        - Count Materials
+        - Count Meshes per Material
+    - Generate the Culled Object Buffer by copying objects from the Object Buffer
+        - Adjust Buffer Size using the counts
+        - Insert using another atomic buffer
+
+- Translucent objects will be sorted. We can cheat by using a z-index instead of a z-coordinate.  
+  This will allow us to sort objects as they are created. We can still bulk render each z-index,  
+  with meshes and objects being grouped by material.