Updated README

Author: dzhdanNV

README.md

@@ -1,25 +1,48 @@
 # NRD SAMPLE
 
-All-in-one repository including all relevant pieces to see [*NRD (NVIDIA Real-time Denoisers)*](https://github.com/NVIDIA-RTX/NRD) in action. The sample is cross-platform, it's based on [*NRI (NVIDIA Rendering Interface)*](https://github.com/NVIDIA-RTX/NRI) to bring cross-GraphicsAPI support.
-
-*NRD sample* is a land for high performance path tracing for games. Some features to highlight:
-- minimalistic path tracer utilizing *Trace Ray Inline*
-- HALF resolution (checkerboard), FULL resolution and FULL resolution tracing with PROBABILISTIC diffuse / specular selection at the primary hit
-- NRD denoising, including occlusion-only and spherical harmonics (spherical gaussians) modes
-- overhead-free multi-bounce propagation (even in case of a single bounce) based on reusing the previously denoised frame
-- SHARC radiance cache
-- reference accumulation
-- several rays per pixel and bounces
-- realistic glass with multi-bounce reflections and refractions
-- mip level calculation
-- curvature estimation
-- native integration of DLSS-SR and DLSS-RR via NGX API (not StreamLine)
+NRD Sample is a high-performance playground and reference implementation for path tracing in games. It provides a comprehensive environment to see [*NRD (NVIDIA Real-time Denoisers)*](https://github.com/NVIDIA-RTX/NRD) in action across all possible use cases and compare it directly with *DLSS-RR*. While *NRD* and *DLSS-RR* are highly competitive today, effective comparison requires enabling *NRD* "SH" mode (set via the `NRD_MODE` macro in `Shared.hlsli`). The sample is designed to demonstrate production-ready path tracing best practices suitable for real-time gaming that balance visual fidelity with high performance. A core focus of the project is high-performance glass and transparency rendering. Built on the [*NRI (NVIDIA Rendering Interface)*](https://github.com/NVIDIA-RTX/NRI), the sample is natively cross-platform, supporting both *D3D12* and *Vulkan*. The ideas from the sample are already used in several *AAA* games and game mods.
+
+Features:
+- best-in-class performance:
+  - RTX 4080 @ 1440p (native) shows ~150 FPS at day time and ~110 FPS at night time in *Bistro* scene (when the importance sampling comes into play)
+- fast path tracing based on *Trace Ray Inline* supporting:
+  - tracing variants:
+    - full resolution: probabilistic diffuse or specular lobe selection at the primary hit (recommended main use case)
+    - half resolution: 0.5 diffuse ray + 0.5 specular ray (checkerboard rendering)
+    - full resolution: 1 diffuse ray + 1 specular ray
+  - material models:
+    - "base color - metalness"
+    - RTXCR hair and skin
+  - smart levels of radiance caching, allowing to do only 1 bounce:
+    - L1 radiance cache: previously denoised frame (essential for refractions)
+    - L2 radiance cache: [*SHARC*](https://github.com/NVIDIA-RTX/SHARC) (global voxel-based cache)
+  - simple and robust importance sampling scheme designed to work with generic emissive pixels, i.e. not analytical lights (not RESTIR)
+  - realistic fast and robust glass with multi-bounce reflections and refractions not requiring denoising
+  - several rays per pixel and bounces (mostly for comparison)
+  - extremely fast implementation of Ray Cones for mip level calculation
+  - curvature estimation
+- *NRD* denoising:
+  - simple integration based on [*NRD Integration*](https://github.com/NVIDIA-RTX/NRD/tree/master/Integration) layer
+  - *RELAX* and *REBLUR* for radiance
+  - *SIGMA* for sun shadows
+  - Spherical Harmonics (Gaussians) mode essential for upscalers
+  - history confidence bumping IQ of dynamic lighting to a new level
+  - *NRD* debug validation layer
+  - denoising best practices including hair denoising
+  - occlusion-only modes
+  - reference accumulation
+  - NRD unit tests
+  - NRD special tests
+- native integration of *DLSS-SR*, *DLSS-RR*, *FSR* and *XeSS* via *NRIUpscaler* extension (not StreamLine)
+ - NOTE: don't forget to modify `NRD_MODE` in `Shared.hlsli` to `SH` to unclock Spherical Harmonics (Gaussians) resolve mode essential for image quality!
 
 GitHub branches:
-- `main` - "all-in-one" branch: all possible options and settings are there. Since this branch covers all aspects, it's for NRD development and maintenance mostly
-- `simplex` - "best practices" branch: optimized for the recommended usage (the path tracer does a probabilistic split at the primary hit, `HitDistanceReconstructionMode::AREA_3X3` enabled in NRD). This branch is recommended to borrow best practices of path tracing and NRD usage. It offers better performance and has less code
+- "best practices" `simplex` branch
+  - optimized for recommended usage (probabilistic split, `HitDistanceReconstructionMode::AREA_3X3` reconstruction). Recommended for learning NRD integration and borrowing PT code. It offers better performance and has less code
+- "all-in-one" `main` branch
+  - contains every possible option and setting, used primarily for NRD development and maintenance.
 
-# BUILD INSTRUCTIONS
+## HOW TO BUILD
 
 - Install [*Cmake*](https://cmake.org/download/) 3.30+
 - Build (variant 1) - using *Git* and *CMake* explicitly
@@ -30,22 +53,25 @@ GitHub branches:
     - Run `1-Deploy`
     - Run `2-Build`
 
-### CMAKE OPTIONS
+*CMake* options:
 
 - `USE_MINIMAL_DATA=OFF` - download minimal resource package (90MB)
+- `RTXCR_INTEGRATION` - use RTXCR for hair and skin rendering, download sample scene
 
-# HOW TO RUN
+## HOW TO RUN
 
-- Run `3-Run NRD sample` script and answer the cmdline questions to set the runtime parameters
+- Run `3-Run` script and answer the cmdline questions to set the runtime parameters
 - If [Smart Command Line Arguments extension for Visual Studio](https://marketplace.visualstudio.com/items?itemName=MBulli.SmartCommandlineArguments) is installed, all command line arguments will be loaded into corresponding window
-- The executables can be found in `_Bin`. The executable loads resources from `_Data`, therefore please run the samples with working directory set to the project root folder (needed pieces of the command line can be found in `3-Run NRD sample` script)
+- The executables can be found in `_Bin`. The executable loads resources from `_Data`, therefore please run the samples with working directory set to the project root folder (needed pieces of the command line can be found in `3-Run` script)
 
-### REQUIREMENTS
+Requirements:
+- any GPU supporting "trace ray inline"
 
-Any ray tracing compatible GPU.
+## USAGE
 
-### USAGE
+By default, NRD is used in common mode. To switch to "SH" or "occlusion-only" modes, modify the `NRD_MODE` macro in `Shared.hlsli` to one of the following: `NORMAL`, `OCCLUSION`, `SH`, or `DIRECTIONAL_OCCLUSION`. RELAX doesn't support AO / SO denoising. If RELAX is the current denoiser, ambient term will be flat.
 
+Controls:
 - Right mouse button + W/S/A/D - move camera
 - Mouse scroll - accelerate / decelerate
 - F1 - toggle "gDebug" (can be useful for debugging and experiments)
@@ -54,8 +80,3 @@ Any ray tracing compatible GPU.
 - Tab - UI toggle
 - Space - animation toggle
 - PgUp/PgDown - switch between denoisers
-
-By default *NRD* is used in common mode. But it can also be used in occlusion-only (including directional) and SH (spherical harmonics) modes in the sample. To change the behavior `NRD_MODE` macro needs to be changed from `NORMAL` to `OCCLUSION`, `SH` or `DIRECTIONAL_OCCLUSION` in `Shared.hlsli`.
-
-Notes:
-- RELAX doesn't support AO / SO denoising. If RELAX is the current denoiser, ambient term will be flat, but energy correct.