Subject: General Tech, Graphics Cards, Shows and Expos | August 15, 2014 - 08:33 PM | Scott Michaud
Tagged: siggraph 2014, Siggraph, OpenGL Next, opengl 4.5, opengl, nvidia, Mantle, Khronos, Intel, DirectX 12, amd
Let's be clear: there are two stories here. The first is the release of OpenGL 4.5 and the second is the announcement of the "Next Generation OpenGL Initiative". They both occur on the same press release, but they are two, different statements.
OpenGL 4.5 Released
OpenGL 4.5 expands the core specification with a few extensions. Compatible hardware, with OpenGL 4.5 drivers, will be guaranteed to support these. This includes features like direct_state_access, which allows accessing objects in a context without binding to it, and support of OpenGL ES3.1 features that are traditionally missing from OpenGL 4, which allows easier porting of OpenGL ES3.1 applications to OpenGL.
It also adds a few new extensions as an option:
ARB_pipeline_statistics_query lets a developer ask the GPU what it has been doing. This could be useful for "profiling" an application (list completed work to identify optimization points).
ARB_sparse_buffer allows developers to perform calculations on pieces of generic buffers, without loading it all into memory. This is similar to ARB_sparse_textures... except that those are for textures. Buffers are useful for things like vertex data (and so forth).
ARB_transform_feedback_overflow_query is apparently designed to let developers choose whether or not to draw objects based on whether the buffer is overflowed. I might be wrong, but it seems like this would be useful for deciding whether or not to draw objects generated by geometry shaders.
KHR_blend_equation_advanced allows new blending equations between objects. If you use Photoshop, this would be "multiply", "screen", "darken", "lighten", "difference", and so forth. On NVIDIA's side, this will be directly supported on Maxwell and Tegra K1 (and later). Fermi and Kepler will support the functionality, but the driver will perform the calculations with shaders. AMD has yet to comment, as far as I can tell.
Image from NVIDIA GTC Presentation
If you are a developer, NVIDIA has launched 340.65 (340.23.01 for Linux) beta drivers for developers. If you are not looking to create OpenGL 4.5 applications, do not get this driver. You really should not have any use for it, at all.
Next Generation OpenGL Initiative Announced
The Khronos Group has also announced "a call for participation" to outline a new specification for graphics and compute. They want it to allow developers explicit control over CPU and GPU tasks, be multithreaded, have minimal overhead, have a common shader language, and "rigorous conformance testing". This sounds a lot like the design goals of Mantle (and what we know of DirectX 12).
And really, from what I hear and understand, that is what OpenGL needs at this point. Graphics cards look nothing like they did a decade ago (or over two decades ago). They each have very similar interfaces and data structures, even if their fundamental architectures vary greatly. If we can draw a line in the sand, legacy APIs can be supported but not optimized heavily by the drivers. After a short time, available performance for legacy applications would be so high that it wouldn't matter, as long as they continue to run.
Add to it, next-generation drivers should be significantly easier to develop, considering the reduced error checking (and other responsibilities). As I said on Intel's DirectX 12 story, it is still unclear whether it will lead to enough performance increase to make most optimizations, such as those which increase workload or developer effort in exchange for queuing fewer GPU commands, unnecessary. We will need to wait for game developers to use it for a bit before we know.
Subject: General Tech, Graphics Cards, Mobile, Shows and Expos | July 7, 2014 - 04:06 AM | Scott Michaud
Tagged: tegra k1, OpenGL ES, opengl, Khronos, google io, google, android extension pack, Android
Sure, this is a little late. Honestly, when I first heard the announcement, I did not see much news in it. The slide from the keynote (below) showed four points: Tesselation, Geometry Shaders, Computer [sic] Shaders, and ASTC Texture Compression. Honestly, I thought tesselation and geometry shaders were part of the OpenGL ES 3.1 spec, like compute shaders. This led to my immediate reaction: "Oh cool. They implemented OpenGL ES 3.1. Nice. Not worth a news post."
Image Credit: Blogogist
Apparently, they were not part of the ES 3.1 spec (although compute shaders are). My mistake. It turns out that Google is cooking their their own vendor-specific extensions. This is quite interesting, as it adds functionality to the API without the developer needing to target a specific GPU vendor (INTEL, NV, ATI, AMD), waiting for approval from the Architecture Review Board (ARB), or using multi-vendor extensions (EXT). In other words, it sounds like developers can target Google's vendor without knowing the actual hardware.
Hiding the GPU vendor from the developer is not the only reason for Google to host their own vendor extension. The added features are mostly from full OpenGL. This makes sense, because it was announced with NVIDIA and their Tegra K1, Kepler-based SoC. Full OpenGL compatibility was NVIDIA's selling point for the K1, due to its heritage as a desktop GPU. But, instead of requiring apps to be programmed with full OpenGL in mind, Google's extension pushes it to OpenGL ES 3.1. If the developer wants to dip their toe into OpenGL, then they could add a few Android Extension Pack features to their existing ES engine.
Epic Games' Unreal Engine 4 "Rivalry" Demo from Google I/O 2014.
The last feature, ASTC Texture Compression, was an interesting one. Apparently the Khronos Group, owners of OpenGL, were looking for a new generation of texture compression technologies. NVIDIA suggested their ZIL technology. ARM and AMD also proposed "Adaptive Scalable Texture Compression". ARM and AMD won, although the Khronos Group stated that the collaboration between ARM and NVIDIA made both proposals better than either in isolation.
Android Extension Pack is set to launch with "Android L". The next release of Android is not currently associated with a snack food. If I was their marketer, I would block out the next three versions as 5.x, and name them (L)emon, then (M)eringue, and finally (P)ie.
Would I do anything with the two skipped letters before pie? (N)(O).
Subject: General Tech, Graphics Cards, Mobile, Shows and Expos | March 17, 2014 - 09:01 AM | Scott Michaud
Tagged: OpenGL ES, opengl, Khronos, gdc 14, GDC
Today, day one of Game Developers Conference 2014, the Khronos Group has officially released the 3.1 specification for OpenGL ES. The main new feature, brought over from OpenGL 4, is the addition of compute shaders. This opens GPGPU functionality to mobile and embedded devices for applications developed in OpenGL ES, especially if the developer does not want to add OpenCL.
The update is backward-compatible with OpenGL ES 2.0 and 3.0 applications, allowing developers to add features, as available, for their existing apps. On the device side, most functionality is expected to be a driver update (in the majority of cases).
OpenGL ES, standing for OpenGL for Embedded Systems but is rarely branded as such, delivers what they consider the most important features from the graphics library to the majority of devices. The Khronos Group has been working toward merging ES with the "full" graphics library over time. The last release, OpenGL ES 3.0, was focused on becoming a direct subset of OpenGL 4.3. This release expands upon the feature-space it occupies.
OpenGL ES also forms the basis for WebGL. The current draft of WebGL 2.0 uses OpenGL ES 3.0 although that was not discussed today. I have heard murmurs (not from Khronos) about some parties pushing for compute shaders in that specification, which this announcement puts us closer to.
The new specification also adds other features, such as the ability to issue a draw without CPU intervention. You could imagine a particle simulation, for instance, that wants to draw the result after its compute shader terminates. Shading is also less rigid, where vertex and fragment shaders do not need to be explicitly linked into a program before they are used. I inquired about the possibility that compute devices could be targetted (for devices with two GPUs) and possibly load balanced, in a similar method to WebCL but no confirmation or denial was provided (although he did mention that it would be interesting for apps that fall somewhere in the middle of OpenGL ES and OpenCL).
The OpenGL ES 3.1 spec is available at the Khronos website.