If we were to ask Oculus what are the main software problems faced by developers of virtual reality experiences, it is likely that performance and latency occupied prominent positions, something that Microsoft intends to change with DirectX 12.
In Anandtech they have made an interesting and very complete article in which they analyze the performance of current GPUs, both AMD and nVidia, under Windows 10 and DirectX 12. The new iteration of this API aims to change the way programs and drivers interact with the operating system to achieve greater efficiency and take advantage of the enormous power of current graphics. To do this, Windows 10 will have a new version of DirectX that promises to be the most revolutionary to date, and is that since AMD showed Mantle it became clear the need for an API for Windows that works with all the brands on the market: AMD, nVidia and Intel, which is increasingly offering better integrated solutions, especially in its Broadwell CPUs and the future Skylake.
Windows 10 will have the new WDDM 2.0 driver model, the biggest leap since the introduction of version 1 in the ill-fated Windows Vista. Such a model will allow many of the current DX11 GPUs to benefit from some of the features that DirectX 12 will offer. And fortunately, both AMD and nVidia are going to support a wide range of GPUs, from the 7000 family in the case of AMD and from the Fermi family (400 and 500) in the case of nVidia.
According to the numbers published by Anandtech, there are significant performance improvements with current graphics as the R9-290X or GTX-980, but are the results, as always, take it with pliers, since they have used the test Star Swarm, the same with the AMD introduced Mantle previously. This is a test designed to show the weak points of the current versions of DirectX based on performing a huge number of drawcalls, which are stuck in the bottleneck of the driver model and the current version of DirectX, so it is to be expected that in practice we will not see the increases of 400-500% that are observed in this test by migrating to DirectX12. You have several performance graphs throughout the Anandtech article, but we stick with this one.
The frametime measures the time it takes the GPU to draw a frame, and it is here that we can find the greatest benefits for virtual reality. The graph shows how a GTX 980 starts the test with a frametime around half that in DirectX 11, but once it stabilizes the test remains constant around 10 ms, that is, the fourth part. We repeat: this is a test designed to show the efficiency of DirectX 12 with respect to its predecessors and in the real world, changes will not be as drastic, but it is evident that the CPU overhead is much smaller, to the point that even processors with only 2 cores maintain a much better rate of frames per second and provide results close to those of his older brothers of 4, while the 6 that we can find in the ranges X79 and X99 Intel does not improve on the 4. If in virtual reality we are going to need fps rates that are constantly around 90, this change is more than necessary.
This revolution in DirectX could not come at a better time, since virtual reality is going to be extremely demanding on our teams and will require all the resources we can provide. Valve already claimed a year ago that SteamOS was pursuing a reduction in latency, and glNext could be Gabe Newell’s company’s big bet for its operating system. Fortunately, Windows is also betting on a change that allows us to take better advantage of our hardware. Both Unity and Unreal Engine will embrace the new version of DirectX, which will help current developers build on the work they’ve already done when it’s time to make the switch.
It is not expected that DirectX 12 and WDDM 2.0 will be incorporated into previous operating systems such as Windows 7, 8 or 8.1, but the fact that the update from them to Windows 10 is free will make this lack anecdotal for most users. If the Oculus Rift CV1 finally arrives at the end of the year coinciding with Windows 10, it is more than likely that it will be the version of Windows recommended by Oculus to get the best possible experience.
