Update README

README.md

@@ -1,2 +1,39 @@
-# soft-3d-engine
+# Software 3D Renderer
+
+## Features
+
+* OBJ model import
+* Depth buffering
+* Texture mapping with bilinear filtering
+* Lighting (ambient, diffuse, specular)
+* Smooth shading
+
+## Goals
+
+### Implement basic GPU pipeline in software
+
+To best learn what a GPU is doing, I wanted to recreate the functionality
+of the GPU in software. It's not anywhere near as fast as a GPU of course,
+but it's not slow either (for a single model that is relatively low-poly).
+
+### Simple code
+
+Coming from a C background, I wanted to use features of C++ that I found made
+the code cleaner and easier to understand while avoiding many of the fancier
+ones that seemed unnecessary. Primarily I leveraged operator overloading for
+vector and matrix operations, and used some simple classes with constructors.
+
+### Good cache performance
+
+The biggest bottleneck of modern CPU performance is latency between memory and
+the CPU, so I tried to use spatial and temporal locality to keep data in the cache.
+Although I chose to go for array-of-structs instead of struct-of-arrays, the
+cache miss rate is fairly low.
+
+### Minimal libraries
+
+I created my own *very* basic OBJ loader (rather than use `tinyobj`) to better
+understand how OBJ files are constructed, along with their respective MTL files.
+I also wrote my own linear algebra functions and classes (rather than use `glm`)
+to better understand the low-level math operations.