Graphics

API Wars – DirectX vs Vulkan vs Metal in 2024

February 25, 2024

Introduction

The battle for supremacy among graphics APIs rages on in 2024, with DirectX, Vulkan, and Metal as the main contenders. As a developer, I need to understand the strengths and weaknesses of each API to make the right choice for my projects. In this article, I will compare the capabilities, performance, platform support, and developer experience of DirectX, Vulkan, and Metal to determine which is best positioned for the future.

DirectX

Overview

DirectX is a graphics API developed by Microsoft. The latest version, DirectX 12, brings several improvements in performance and efficiency over previous versions.

Strengths

Mature and stable API – DirectX has been around for over 20 years and is the most mature graphics API. It offers stable tools and documentation.
Strong hardware vendor support – DirectX is deeply integrated with Windows and has broad support from GPU vendors like Nvidia, AMD, and Intel.
Ease of development – DirectX has a straightforward API design and excellent documentation. Programming with DirectX is easier compared to Vulkan.
Wide platform support – DirectX runs on all Windows platforms from Windows 7 onwards.

Weaknesses

Windows exclusive – DirectX only works on Windows platforms, limiting its reach.
Higher CPU overhead – DirectX 12 reduced overhead compared to DirectX 11 but still has higher CPU utilization than Vulkan.
Limitations for demanding games – DirectX’s multithreading support falls behind Vulkan, impacting performance in heavy AAA games.

Vulkan

Overview

Vulkan is an open-source, cross-platform graphics and compute API maintained by the Khronos group. It offers lower overhead and better utilization of multi-core CPUs compared to DirectX 12.

Strengths

Cross-platform – Vulkan works across Windows, Linux, macOS, Android, and more. This makes it very attractive for game developers looking for wider reach.
Lower CPU overhead – Vulkan is designed to have minimal driver overhead, allowing better CPU/GPU parallelism. This translates to higher frame rates in games.
Explicit control – Vulkan gives developers greater control over GPU commands. This allows optimization for specific hardware.
High performance – The low overhead and asynchronous design of Vulkan allows it to extract maximum performance out of modern GPUs.

Weaknesses

Challenging to program – Vulkan has a verbose, complex API requiring strong graphics programming skills. Debugging and profiling tools are still maturing.
Immature tools/documentation – Being a newer API, the developer tools and documentation around Vulkan are not as mature as DirectX.
Limited game engine support – Fewer game engines support Vulkan compared to DirectX, although support is improving.

Metal

Overview

Metal is a low-level graphics API developed by Apple and used across their platforms like iOS, macOS, tvOS, iPadOS, and watchOS.

Strengths

High efficiency on Apple chips – Metal is designed to exploit the unique capabilities of Apple-designed GPUs. It delivers excellent performance on Apple silicon.
Cross-Apple platform – Metal provides a unified graphics API across Apple’s ecosystems, from phones to computers.
Objective-C integration – Metal interfaces very cleanly with Objective-C, making adoption easier for Apple developers.
Console-to-mobile portability – Makes it easier to port games between Apple consoles (Apple TV) and mobile devices.

Weaknesses

Apple-only – Metal only works on Apple platforms, limiting its reach for game developers.
Immature on Mac – While mature on iOS, Metal on macOS still lags Vulkan and DirectX in features and performance.
Minimal hardware vendor support – Nvidia and AMD have limited incentive to optimize their macOS drivers for Metal.

Verdict

For developing games targeting Windows first, DirectX 12 remains the safe, stable choice in 2024 thanks to its maturity, robustness, and widespread game engine support.

However, for multi-platform development, Vulkan is hard to ignore. Its cross-platform capabilities and nearly bare-metal efficiency give it the performance advantage in demanding AAA titles. As tools and support for Vulkan improve, it is well positioned to become the leading graphics API.

On Apple platforms, Metal remains the default choice. It delivers great performance on Apple silicon, although its scope is limited by Apple-only platform support.

Overall, while DirectX maintains dominance on Windows, Vulkan’s cross-platform nature gives it the edge to become the de facto graphics API of the future across Windows, Linux, and mobile. Metal will continue to serve Apple’s walled gardens.

The Future

Improving Vulkan adoption

While Vulkan offers compelling advantages, adoption has been slowed by its challenging programming model. However, efforts are underway to simplify Vulkan:

New Vulkan SDK tools like the Vulkan Mesh Shader make programming easier.
Middleware engines like Unity and Unreal Engine are adding Vulkan support, hiding the complexity from developers.
Apple’s MoltenVK allows Vulkan to run on Metal, expanding the reach of Vulkan-based games.
Nvidia’s new RTX GPUs demonstrate significant performance gains with Vulkan over DirectX 12 in ray tracing workloads.

DirectX still going strong

Despite Vulkan’s rise, DirectX will remain relevant on Windows through the continued update and improvement of DirectX 12.

DirectX 12’s new mesh shading feature brings it close to par with Vulkan in some workloads.
DirectX Raytracing is maturing into an easy way to add ray tracing effects without Vulkan’s programming burden.
The new DirectStorage API takes advantage of NVMe SSDs to stream assets faster.

Conclusion

While Vulkan appears poised to become the leading cross-platform graphics API, thanks to its overhead advantages, DirectX will remain the preferred choice for Windows-centric game developers who value its maturity and robust tooling. Metal will continue to serve Apple platforms well.

The competition for lower overhead, reduced CPU utilization, and better multi-threading support will ultimately benefit all developers through forcing continual improvement of these critical graphics APIs.