Adding some GPU docs and creating output directories automatically.

docs/gpu.md

@@ -1,5 +1,57 @@
 # GPU Documentation
 
+## Options
+
+### General
+
+See the top of [src/xenia/gpu/gpu.cc](https://github.com/benvanik/xenia/blob/master/src/xenia/gpu/gpu.cc).
+
+`--vsync=false` will attempt to render the game as fast as possible instead of
+waiting for a fixed 60hz timer.
+
+### OpenGL
+
+See the top of [src/xenia/gpu/gl4/gl4_gpu.cc](https://github.com/benvanik/xenia/blob/master/src/xenia/gpu/gl4/gl4_gpu.cc).
+
+Buggy GL implementations can benefit from `--thread_safe_gl`.
+
+## Tools
+
+### Shader Dumps
+
+Adding `--dump_shaders=path/` will write all translated shaders to the given
+path with names based on input hash (so they'll be stable across runs).
+
+### xe-gpu-trace-viewer
+
+To quickly iterate on graphical issues, xenia can dump frames (or sequences of
+frames) while running that can be opened and inspected in a separate app.
+
+The basic workflow is:
+
+1. Capture the frame in game (using F4) or a stream of frames.
+2. Add the file path to the xe-gpu-trace-viewer Debugging command line in
+Visual Studio.
+3. Launch xe-gpu-trace-viewer.
+4. Poke around, find issues, etc.
+5. Modify code.
+6. Build and relaunch.
+7. Goto 4.
+
+#### Capturing Frames
+
+First, specify a path to capture traces to with
+`--trace_gpu_prefix=path/file_prefix_`. All files will have a randomish name
+based on that.
+
+When running xenia.exe you can hit F4 at any time to capture the next frame the
+game tries to draw (up until a VdSwap call). The file can be used immediately.
+
+#### Capturing Sequences
+
+Passing `--trace_gpu_stream` will write all frames rendered to a file, allowing
+you to seek through them in the trace viewer. These files will get large.
+
 ## References
 
 ### Command Buffer/Registers