Quake BSP map viewer in Vulkan

This is a multithreaded BSP tree Vulkan renderer written in C++ and a port of the same viewer written in OpenGL. It handles basic geometry and curved patch rendering but with no support for game-specific shaders, entities etc. It implement PVS and frustum culling so performance is optimal. At the moment only Quake III Arena maps are supported but an interface is provided for adding other BSP versions in the future.

Building

The project should work out of the box with latest Vulkan SDK (tested against SDK 1.1.82.1) and Visual Studio 2015+

Building on Linux and MacOS

Assuming that the Vulkan SDK is already downloaded and properly set up on your target platform:

• set the VULKAN_SDK environment variable pointing to the location of downloaded Vulkan SDK
• download and install SDL2 (libsdl2-dev 2.0.7 or higher for Linux, SDL2.framework 2.0.8 or higher for MacOS)
• run the Makefile (Linux) or XCode project (MacOS) to build the application

MacOS uses the Vulkan loader bundled with the SDK, rather than directly linking against MoltenVK.framework. This is done so that validation layers are available for debugging.

Building for mobile: iOS and Android

Disclaimer: there are no plans to introduce mobile-specific controls in the application, since its purpose is solely to demonstrate how to pull off a Vulkan renderer that "just works". For clarity, both Android and iOS code makes use of SDL2 in the same way as the desktop version - this is a terrible idea and something you should NOT do in your own applications. The proper way is to make direct use of the native APIs for minimum overhead.

Requirements:

• set the VULKAN_SDK environment variable pointing to the location of downloaded Vulkan SDK
• download and extract SDL 2.0.8 source code (NOT runtime libraries!) into contrib folder

Android:

• Android Studio 3.0 or higher with CMake and Android SDK installed
• Android NDK with ANDROID_NDK_HOME environment variable set and pointing to its location (using latest NDK is highly recommended due to better validation layer support)

Enter the android folder and run ./gradlew assembleDebug for debug build (with validation layers enabled by default) or ./gradlew assembleRelease for release build. This application uses dedicated Vulkan loader code on Android instead of linking directly to dynamic library in the NDK, so it's possible to run it on Vulkan-capable hardware with API level 23 or lower.

iOS:

• XCode 9.0 or higher, MoltenVK requires iOS 9+ to work

Running the project in XCode should work out of the box. The build may fail if the textures and models folders don't exist in the repo root directory - if you want to run the app regardless, simply remove them from resources and "Copy Files" build steps. Note that iOS version does not support a dedicated Vulkan loader or validation layers - this is a Vulkan SDK limitation that may be removed in the future. Simulator builds are also not available due to lack of Metal support.

Usage

Running the viewer:

QuakeBspViewer.exe

Running the viewer with multithreaded renderer:

QuakeBspViewer.exe -mt

Use tilde key (~) to toggle statistics menu on/off. Note that you must have Quake III Arena textures and models unpacked in the root directory if you want to see proper texturing. To move around use the WASD keys. RF keys lift you up/down and QE keys let you do the barrel roll.

OpenGL vs Vulkan

Performance comparison between OpenGL, Vulkan and Vulkan multithreaded versions (tested on Intel i5 and GTX 970). Differences become more apparent as the amount of rendered geometry increases. All measurements are average values collected when rendering the attached sample BSP with all textures present:

Sidenote: The application detects and uses maximum number of threads when launched in multithreaded mode. Because of this, as the number of available threads increases, you might notice a slight performance degradation when compared to singlethreaded version. This is expected, since the visible faces are divided between threads without taking into consideration the BSP leaves they belong to. This might lead to a situation where with large amount of threads the work is not evenly distributed if PVS and frustum culling are enabled. Since this is a "proof of concept" project, there are no plans to improve this behavior.

Dependencies

This project uses following external libraries:

• stb_image library for texture loading
• SDL2 library for window/input
• Vulkan Memory Allocator for painless memory management of Vulkan resources

Vulkan code overview

For people interested in learning Vulkan and jumping into core features, the renderer/vulkan folder contains all files related to creating buffers, instances, surfaces and command lists. Note that this is not an attempt at writing an overly abstract rendering engine and few settings are tailored for this particular project. Core BSP and overlay rendering is done in src/Q3BspMap.cpp and src/renderer/Font.cpp. Global Vulkan handles (instance, device, etc.) are stored in src/RenderContext.cpp.

Keyword list:

• multiple pipeline rendering
• multithreaded command buffer generation (double buffered primary presentation buffers and secondary buffers for threads)
• pipeline dynamic state, derivatives and cache
• uniform buffer objects and push constants
• texture mapping (filtered and unfiltered)
• memory allocation handled using VMA
• validation layers enabled by default in debug builds
• multisampling (MSAA) using maximum sample count supported by hardware
• mipmapping

Vulkan references

• https://www.khronos.org/registry/vulkan/specs/1.0/html/vkspec.html
• https://arm-software.github.io/vulkan-sdk
• https://www.khronos.org/assets/uploads/developers/library/2016-vulkan-devday-uk/7-Keeping-your-GPU-fed.pdf
• https://github.com/KhronosGroup/Vulkan-Docs/wiki/Synchronization-Examples
• https://developer.nvidia.com/sites/default/files/akamai/gameworks/blog/munich/mschott_vulkan_multi_threading.pdf