cleanup and refactoring

raytracer/nvpro_core/fileformats/README.md

@@ -0,0 +1,53 @@
+## Table of Contents
+- [khr_df.h](#khr_dfh)
+- [nv_ktx.h](#nv_ktxh)
+- [tiny_converter.hpp](#tiny_converterhpp)
+
+## khr_df.h
+
+This header defines a structure that can describe the layout of image
+formats in memory. This means that the data format is transparent to
+the application, and the expectation is that this should be used when
+the layout is defined external to the API. Many Khronos APIs deliberately
+keep the internal layout of images opaque, to allow proprietary layouts
+and optimizations. This structure is not appropriate for describing
+opaque layouts.
+
+
+## nv_ktx.h
+
+A mostly self-contained reader and writer for KTX2 files and reader for KTX1
+files. Relies on Vulkan (for KTX2), GL (for KTX1), and the
+Khronos Data Format.
+
+Sample usage for reading files:
+
+```cpp
+KTXImage image;
+ErrorWithText maybe_error = image.readFromFile("data/image.ktx2");
+if(maybe_error.has_value())
+{
+// Do something with the error message, maybe_error.value()
+}
+else
+{
+// Access subresources using image.subresource(...), and upload them
+// to the GPU using your graphics API of choice.
+}
+```
+
+Define NVP_SUPPORTS_ZSTD, NVP_SUPPORTS_GZLIB, and NVP_SUPPORTS_BASISU to
+include the Zstd, Zlib, and Basis Universal headers respectively, and to
+enable reading these formats. This will also enable writing Zstd and
+Basis Universal-compressed formats.
+If you're using this inside the nvpro-samples framework, you can add all
+three quickly by adding _add_package_KTX() to your dependencies
+in CMakeLists.txt.
+
+
+## tiny_converter.hpp
+
+Class TinyConverter
+
+> This class is used to convert a tinyobj::ObjReader to a tinygltf::Model.
+