GDC 2025: DirectX State of the Union

At GDC this year, the DirectX team has unveiled significant advancements aimed at accelerating your projects and enhancing your development processes, with substantial updates in raytracing and PIX workflows. In case you missed it, here's a breakdown of the latest improvements and new features available soon to developers.

DirectX Raytracing 1.2 (DXR 1.2)

DXR 1.2 represents a substantial leap forward in raytracing performance, achieving improvements of up to 40% in complex scenes, as demonstrated by Remedy Entertainment with their Alan Wake 2 showcase at GDC. This upgrade facilitates smoother frame rates and richer, more detailed raytraced visuals.

Two key features introduced in DXR 1.2 are:

• Opacity Micro-Maps (OMM): This innovation reduces the necessity for any hit shader invocations by efficiently retrieving alpha information through dedicated hardware during ray traversal. OMM significantly optimizes performance, especially with high-detail opacity data such as alpha textures, reducing shader invocations without sacrificing visual fidelity.

• Shader Execution Reordering (SER): SER enhances execution and data coherency by allowing developers to instruct the driver on thread reordering. This optimization groups similar shading tasks together, lowering computational overhead and improving overall shading efficiency.

Together, OMM and SER deliver substantial performance benefits, making advanced real-time raytracing practical and accessible. Developers can experience these enhancements firsthand with the DXR 1.2 preview launching in late April 2025.

Cooperative Vectors

This exciting new feature coming to Direct3D and High-level Shader Language (HLSL) will revolutionize real-time graphics by enabling seamless integration of machine learning inferences directly into the graphics pipeline. Cooperative vectors is designed to enhance the efficiency and performance of graphics rendering by leveraging advanced mathematical principles. By enabling Windows applications to take advantage of dedicated hardware acceleration for these computations, cooperative vectors pave the way for more realistic and high-quality visual experiences. DirectX is going to help us all build the future of neural rendering starting with the cooperative vectors preview release in April!

DirectX Tools and Debugging Enhancements

DirectX’s powerful suite of development tools will also see substantial updates, particularly within PIX:

• PIX API: The new PIX API offers developers programmatic access to functionalities previously confined to the PIX user interface. Featuring a familiar C++ structure similar to D3D12 and supported in C# and Python, this API supports all PIX features, including GPU and timing captures, performance analysis, performance statistics dumping, and visual regression testing. The PIX API will enter private preview in April 2025; interested developers can contact askwinpix@microsoft.com for early access.

• Refreshed UI and Layout Editor: PIX’s UI receives a modern overhaul for improved usability, incorporating modern design principles. This includes the reintroduction of file layout and help options, as well as a new capture UI that displays all launch arguments and options in a more accessible manner. The Layout Editor has been significantly improved, allowing developers to easily undock, drag, and move different parts of the UI, similar to Visual Studio. This makes it simpler to add new views, split panes, and customize the workspace. These updates simplify workspace customization and streamline workflows, available with PIX on Windows in April.

• Custom Visualizer Improvements: Enhancements to the custom visualizer allow for greater flexibility and precision in visualizing complex data structures within the PIX tool. By enabling custom visualizations for buffers, meshes, and textures, developers can now reinterpret these resources in ways that are more meaningful and tailored to their specific needs, improving the debugging process and also enhancing the overall efficiency of development workflows. Additionally, the ability to write custom HLSL shaders for these visualizations means that developers can include any necessary game code to accurately represent their data, leading to more insightful and actionable debugging sessions. This will be available in the PIX on Windows release in April.

• Day-One DXR 1.2 Support: PIX will offer immediate integration with all new DXR 1.2 features, ensuring seamless transition from launch.
  

Additional PIX enhancements coming in April include:

• Improved reliability of PIX captures with several D3D updates.

• A new PIX UI integrating the D3DConfig command line utility for controlling parts of D3D such as forcing on features or controlling the debug layer.

• New image visualizers, such as seeing quad utilization and the VRS shading rate image.

• Significant improvements to the Acceleration Structure Viewer.

Updates to Windows Advanced Rasterization Platform (WARP)

WARP, the CPU-based software renderer for DirectX, also receives major updates enhancing its capabilities and performance. WARP is essentially a software renderer for DirectX, running on the CPU without requiring a GPU. This makes it an excellent tool for testing new features on systems without compatible GPUs or for diagnosing potential driver issues. The recent updates have made WARP fully compliant with DirectX 12 Ultimate, supporting advanced features like raytracing, mesh shaders, and work graphs. Additionally, performance improvements have been made, allowing for higher frame rates and more extensive testing scenarios. These updates ensure that WARP remains a valuable tool for developers, providing a reliable and efficient software rendering solution.

With DirectX, we remain committed to delivering cutting-edge tools and technology to empower developers in creating the next-generation real-time graphics experiences. To stay up to date, stay tuned to our blogs for release announcements and details in April: DirectX Developer Blog and PIX on Windows

If you're interested in PIX API private preview access, reach out to the team.