Getting Steam to run with proprietary nVidia.

According to this earlier posting, I had switched my Debian / Stretch, Debian 9 -based computer named ‘Plato’ from the open-source ‘Nouveau’ drivers, which are delivered via ‘Mesa’ packages, to the ‘proprietary nVidia drivers’, because the latter offer more power, in several ways.

But then one question which we’d want an answer to, is how to get “Steam” to run. Just from the Linux package manager, the available games are slim picking, and through a Steam membership, we can buy Linux-versions of at least some powerful games, meaning, to pay for with money.

But, when I tried to launch Steam naively, which used to launch, I only got a message-box which said, that Steam could not find the 32-bit version of ‘libGL.so’ – and then Steam died. This temporary result ‘makes sense’, because I had only installed the default, 64-bit libraries, that go with the proprietary packages. Steam is a 32-bit application by default, and I have a multi-arch setup, as a prerequisite.

And so my next project became, to create a 32-bit as well as the existing, 64-bit interface to the rendering system.

The steps that I took assume, that I had previously chosen to install the ‘GLVND’ version of the GLX binaries, and unless the reader has done same, the following recipe will be incorrect. Only, the ‘GLVND’ packages which I initially installed, are not listed in the posting linked to above; they belonged to the suggested packages, which I wrote I had written down on paper, and then added to the command-line, which transformed my graphics system.

When I installed the additional, 32-bit libraries, I did get a disturbing error message, but my box still runs.

Continue reading Getting Steam to run with proprietary nVidia.

xscreensaver Bug With Latest Proprietary nVidia Graphics Drivers

As described in this posting, I have just applied a major software-update to the computer I name ‘Plato’, in which I replaced its open-source graphics drivers, with the proprietary nVidia drivers, suitable for its graphics card, and for its Linux-build.

That would be drivers version ‘375.82-1~deb9u1′ , from the package manager, for a ‘Debian 9.4′ system.

I have just noticed a major bug, which other people should know about, before they also decide to go with the proprietary drivers. They tend to cause some malfunction with OpenGL-based ‘xscreensaver’ screen-savers, version ‘5.36-1′ .

The bug seems to be, that if I use the graphical configuration tool to preview several screen-savers, when I switch from one screen-saver to another, the previous GL-screen-saver being previewed fails to terminate, which in turn causes the configuration window to freeze, so that the next-chosen screen-saver cannot be previewed. A small blank rectangle takes its place, in the configuration window. When this happens, I actually need to ‘kill -9′ the screen-saver-process – belonging to the screen-saver in question and not ‘/usr/bin/xscreensaver’ – the former of which is taking up 100% of 1 CPU core with nice-time, before I can continue previewing screen-savers.

The problem with this as I see it is, it could also happen after the screen-saver has locked the screen, and when I have entered my password to unlock it. The mere fact that I was always able to unlock one GL-based screen-saver in the past was good in itself, but may only have been luck! The strangeness with which my bug seems to differ from other users’ bug-reports, is that when my OpenGL-based screen-saver was rendering to the root window – i.e., to the whole screen – it did exit properly when unlocked by me.

So as it currently stands, I have set my screen-saver on the computer ‘Plato’, to just a blank screen… :-(

At the same time, OpenGL applications seem to run just fine, like this example, just tested:

screenshot_20180430_142338

However, since the description of the screen-saver packages in the package manager states “GL(Mesa)” screen-savers, it may be better just to ‘remove’ the ‘xscreensaver-gl’ and ‘xscreensaver-gl-extra’ packages.

I found out, that this bug also affects ‘rss-glx 0.9.1-6.1′ .

(Updated 04/30/2018, 19h25 … )

Continue reading xscreensaver Bug With Latest Proprietary nVidia Graphics Drivers

OpenGL | ES

I have frequently blogged about the existence of ‘OpenGL‘, which is both an open-source alternative to ‘DirectX’, and an API for communicating 3D graphics directly to a graphics card. It mainly gets used on PCs.

Well I thought I should mention, that the version of that API which gets used in smart-phones and tablets, including under Android and iOS, is actually named ‘OpenGL | ES‘ . The ‘ES’ stands for ‘Embedded Systems’.

(Update 12/09/2017 : )

Some users might wonder, if they use the Android utility I suggested above, why their devices show as having both GLES 1.x and GLES 3.y .

My personal guess would be, that the compositing only requires GLES 1.x , so that as long as the hardware provides that, Android will run. OTOH, If we’re playing “Baldur’s Gate”, then this app will require the full power of GLES 3.y …

Dirk

 

Quickie: How 2D Graphics is just a Special Case of 3D Graphics

I have previously written in-depth, about what the rendering pipeline is, by which 3D graphics are rendered to a 2D, perspective view, as part of computer games, or as part of other applications that require 3D, in real time. But one problem with my writing in-depth might be, that people fail to see some relevance in the words, if the word-count goes beyond 500 words. :-)

So I’m going to try to summarize it more-briefly.

Vertex-Positions in 3D can be rotated and translated, using matrices. Matrices can be composited, meaning that if a sequence of multiplications of position-vectors by known matrices accomplishes what we want, then a multiplication by a single, derived matrix can accomplish the same thing.

According to DirectX 9 or OpenGL 2.x , 3D objects consisted of vertices that formed triangles, the positions and normal-vectors of which were transformed and rotated, respectively, and where vertices additionally possessed texture-coordinates, which could all be processed by “Vertex Pipelines”. The output from Vertex Pipelines was then rasterized and interpolated, and fed to “Pixel Pipelines”, that performed per-screen-pixel computations on the interpolated values, and on how these values were applied to Texture Images which were sampled.

All this work was done by dedicated graphics hardware, which is now known as a GPU. It was not done by software.

One difference that exists today, is that the specialization of GPU cores into Vertex- and Pixel-Pipelines no longer exists. Due to something called Unified Shader Model, any one GPU-core can act either as a Vertex- or as a Pixel-Shader, and powerful GPUs possess hundreds of cores.

So the practical question does arise, how any of this applies to 2D applications, such as Desktop Compositing. And the answer would be, that it has always been possible to render a single rectangle, as though oriented in a 3D coordinate system. This rectangle, which is also referred to as a “Quad”, first gets Tessellated, which means that it receives a diagonal subdivision into two triangles, which are still references to the same 4 vertices as before.

When an application receives a drawing surface, onto which it draws its GUI – using CPU-time – the corners of this drawing surface have 2D texture coordinates that are combinations of [ 0 ] and ( +1 ) . The drawing-surfaces themselves can be input to the GPU as though Texture Images. And the 4 vertices that define the position of the drawing surface on the desktop, can simply result from a matrix, that is much simpler than any matrix would have needed to be, that performed rotation in 3D etc., before a screen-positioning could be formed from it. Either way, the Vertex Program only needs to multiply the (notional) positions of the corners of a drawing surface, by a single matrix, before a screen-position results. This matrix does not need to be computed from complicated trig functions in the 2D case.

And the GPU renders the scene to a frame-buffer, just as it rendered 3D games.

Continue reading Quickie: How 2D Graphics is just a Special Case of 3D Graphics