Just four and a half months after releasing the OpenGL 4 specification, the Khronos Group has released the final version of the OpenGL 4.1 specification. OpenGL 4.0 brought feature parity with Direct3D 11's new features—in particular, compute shaders and tessellation—and with 4.1, the Khronos Group claims that it is surpassing the functionality offered in Microsoft's 3D API.
OpenGL 4.1 includes more robust error handling to make running buggy programs safer, richer debugging features to make developing OpenGL software simpler, and a new ability to save and restore programs written to use the shaders found in modern video hardware. Shader programs, an important part of modern 3D software and hardware, are written in a hardware-independent language, and then compiled at runtime by the OpenGL driver. This allows the programs to be properly optimized for the specific GPU hardware. The downside is that compilation can be a slow process, and if it has to be performed each time a game starts, for example, it can lead to noticeable delays. OpenGL 4.1 allows software to cache the compiled programs and therefore bypass the slow compilation step.
OpenGL 4.1 also strengthens OpenGL's cross-platform appeal. OpenGL has three guises; the standard OpenGL used in desktop and workstation hardware, OpenGL ES used in various embedded platforms such as the iPhone and PlayStation 3, and WebGL, which enables webpages to include 3D OpenGL graphics without needing browser plugins. Previously, OpenGL ES was slightly incompatible with conventional OpenGL. With OpenGL 4.1, that's no longer the case; the desktop platform is a superset of the embedded one. This will ease porting and development, as it will enable a common codebase to be used across both desktop and embedded applications, and allow embedded developers to use the often superior development infrastructure that desktop systems provide.
The more robust error handling in OpenGL 4.1 will strengthen WebGL. Traditionally, OpenGL drivers have only been exposed to "trusted" applications—3D software running at the user's request on the desktop. Errant programs that tried to access memory improperly would crash or misbehave, but this was an acceptable performance decision. With WebGL, that's no longer the case; webpages have a long history of attempting malicious activities, and WebGL gives malicious pages the ability to try to attack video drivers. The new, more robust error handling allows WebGL vendors to make the OpenGL driver stricter in the checks it applies, providing some protection against such attacks.
Whether this truly constitutes a leapfrogging of Direct3D 11 is not obvious. Direct3D has long had the ability to save compiled shaders, and has long provided rich debugging features. What Direct3D doesn't offer, however, is the kind of cross-platform support that OpenGL has. Obviously, Direct3D is only available on Windows; Linux and Mac OS X are OpenGL-only. Microsoft's OpenGL ES equivalent is, roughly speaking, XNA. XNA is supported on desktop Windows, the Xbox 360, and the forthcoming Windows Phone 7 platform, but, though it's conceptually similar to Direct3D, it is not programmatically identical.
Further, Microsoft has no kind of WebGL equivalent. If WebGL gains traction—which is certainly not inevitable, especially given Microsoft's apparent reluctance to include it in Internet Explorer—then there may be a substantial increase in the amount of OpenGL code being written.
With OpenGL 4.0, the Khronos group also released OpenGL 3.3, which provided OpenGL 3-level hardware with those OpenGL 4 features that they could support. Although the new features found in OpenGL 4.1 do not require any OpenGL 4-specific hardware, the group has decided not to create a corresponding OpenGL 3.4 release.
NVIDIA says that it will release OpenGL 4.1 drivers on or before Wednesday, with AMD (ATI) releasing them shortly. As is now traditional, Apple has given no indication of when, if ever, it will update Mac OS X's OpenGL drivers to support the new standard; the company does not have full support for OpenGL 3.0.
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