Fractal Architect 4 render engine

The Fractal Architect 4 render engine, given robust, quality drivers, has worked on all versions of Mac OS (except partially on High Sierra because of driver problems). AMD, Nvidia, and Intel GPUs all can be used. It supports CUDA  and OpenCL.

The Apple CPU OpenCL driver has always worked over the last 7 years, so when the GPU drivers are defective, users can still use the app with CPU rendering.

Nvidia GPUs and CUDA are also supported (but not in the FA 4 Mac App store version because of app sandboxing) on both Mac OS and Windows 10.

It has  been ported to Windows 10 and there it also works with AMD and Nvidia GPUS.  Intel GPUs worked with 1 version of Intel’s OpenCL drivers but not with a later OpenCL driver update. (So the Windows platform is also affected by driver quality issues.)

Intel’s OpenCL driver for CPU on Windows 10 does not work with the FA 4 render engine.

The render engine is a fantastic test case for GPU compute and can be used by OpenCL and CUDA driver developers to validate the quality of their drivers. The render engine itself is open source and licensed with LGPL license.

FAEngine – FA 4 Open Source Render Engine

The app itself is even easier to use for driver quality testing on Mac OS. Metal is supported by the app (but not in the open source render engine).

Earlier versions of the render engine have worked on all versions of Mac OS since 2009.

Fractal Software is made by Indie Hobbyists

Let’s make sure that is understood. There has never been a commercially successful product in this app category.

Right now, myself and Andreas Maschke are the most active developers in the flame fractal app category. I am the author of Fractal Architect. Andreas is the developer of JWildfire. Both our products are huge, with multiple man years of development. (For FA, it is 9 man years.) I receive testing support from Lennart Ostman, for which I am deeply grateful.

That gives the illusion of a huge team creating these products, but it is just 2 hobbyists doing what we love best. We do it for love, as I have never been paid a single cent for my time. I receive no financial support to produce this product. All test hardware is paid using app revenues. (The remainder I pay out of my own pocket.)

Fractal Architect 5 (in development) is about 3x larger than the historic Photoshop 1 when it was first released 27 years ago.

So when you expect Facebook pages, forums, blog, and tons of support, we are not Adobe with billions in revenue and 1000’s of employees. Remember I make NO money from this app.

All app revenues pays for test hardware – nothing else.

Is it time to remove GPU rendering support from the app?

Let’s face it. Apple has done a terrible job producing reliable drivers for OpenCL and Metal compute shaders. Each Mac OS update brings the terror of: Did Apple kill the drivers this time?

Since March 2017, the state of OpenCL drivers for AMD GPUs has been: Unusable

Either the app crashes or you get a total system lockup with OpenCL AMD rendering. (late 2016 MacBook Pro with AMD GPU)

With about 100 different Mac configurations released in the last 6 years that have GPUs, your results will probably be very different.

For the 5 previous years, the AMD OpenCL drivers had been rock solid.

Fractal Architect is the “Rosetta Stone” for GPU compute testing. It allows you to easily switch render devices between OpenCL, Metal, and CUDA. It allows you to check their LLVM compilers for their ability to compile the extremely complex kernels used by the app.

It allows you to profile and compare performance between devices and between different Mac models.

But supporting GPU rendering is very expensive. Guess who pays for all of the test Macs?

The revenue base to support this GPU support feature is tiny.  Flame fractal apps are a micro niche. To date (since 2009) the entire revenue from the app goes toward buying test hardware and nothing else !

This year, because of driver quality problems, worldwide sales of the app are now so low that I can only buy 1 test Mac every 3 years. I cant test the app on a current generation AMD GPU on a low end MacBook Air. I can’t test next years AMD GPU on last year’s Mac.

So should:

A) GPU rendering be removed from the app as test hardware is cost prohibitive?

or B) should it be left in because it will probably work with fixed drivers on future GPUs?

Perma-Broke Apple AMD OpenCL Drivers

Its now 7 months of broken OpenCL drivers for the AMD GPU in the late 2016 Touch Bar MacBook Pro. (Since Sierra 10.12.4. Affects all builds of High Sierra.)

Metal drivers work correctly for the Mac’s AMD GPU, but some fractals (10 to 20%) render incorrectly. So I don’t recommend Metal as an alternative.  (Note: this incorrect render output is a new problem. Older Metal driver versions did not have this problem. The drivers in Q1 2017 worked so well. Now it is Q4 2017.

The legacy of Apple’s unusable GPU compute drivers goes on and on.

OpenCL/Metal Rendering on Intel GPUs Works !

Fractal Architect version 4.5.0 submitted to Apple today (Dec 14, 2016) makes it possible to use either OpenCL or Metal GPU rendering with Intel processors.  This capability requires Mac OS Sierra.

With Mac OS Sierra, it seems that all Intel CPUs (2013 and later) having Intel HD, Intel Iris, or Intel Iris Pro GPUS can now take advantage of either OpenCL or Metal  rendering for HUGE speed increases. For example, a 2013 MacBook Air gets approx. a 9x speed increase !  That is like a baby going from crawling to Olympic sprinting.

On Macbook Pros and iMacs having both a discrete AMD GPU and an Intel processor with its integrated GPU, you can use both GPUs together for rendering. This gives you almost twice the rendering speed !

Thank you Apple for giving us great OpenCL and Metal drivers on Mac OS Sierra !!

Note: Older versions of Mac OS and Macs produced in 2012 or earlier may have compatibility problems. (But CPU rendering works fine.)

Mac OS Sierra and GPU Rendering

Now that it is release day, how does Sierra handle GPU rendering using Fractal Architect 4 ?

Fractal Architect is a hard core test for GPU compute drivers and seems to the best test tool available for GPU vendors to evaluate the quality of their driver/runtime APIs.

We tested with 5 different Mac configurations, and this is what we found (over 100 different Mac configurations have been released by Apple that have Metal/OpenCL compatible GPUs).

Evaluating Sierra Before Updating to It

You should evaluate Sierra with your favorite apps before committing to a full upgrade.

Doing a full Time Machine backup before doing a full upgrade is a very good idea. There is no easy way back to El Capitan, once you have committed to a full upgrade

You can install Sierra on to an external hard drive and then boot off that external hard drive to try it out. I recommend using a Samsung T3 Portable Flash SSD drive because of its great performance. Traditional external hard drives can be painfully slow.

Metal Rendering

Metal rendering on recent Intel GPUs works very well. Render speed on Intel Iris Pro close to that of AMD GPU on 2015 Macbook Pro.

2013 and earlier Intel GPUs have a compile problem  on Sierra, but not on El Capitan. 

If you only have a Intel GPU in your Mac, you will want to evaluate Sierra first (before upgrading to it), to see if your Intel GPU is compatible with Metal rendering

Metal rendering on AMD GPUs is much faster on Sierra than El Capitan.

Metal rendering on older 2012 Nvidia GPU works. Other years Nvidia GPUs were not tested.

OpenCL Rendering

OpenCL on older Nvidia and AMD GPUs works (unlike El Capitan where they were broken). On more recent GPUs, OpenCL works about the same as in El Capitan.

OpenCL on Intel GPUs still broken – but of course Metal can now be used on more recent Intel GPUs.

CUDA Rendering on Nvidia GPUs

CUDA does not work on any sandboxed app sold through the Mac App Store. Fractal Architect 4-CUDA adds CUDA as an alternate rendering platform. (It was written for users affected by the horrible Nvidia OpenCL drivers released with Mac OS El Capitan.)

Bad News for Sierra: Nvidia has not yet released usable CUDA drivers for Sierra. Stay on El Capitan if you need CUDA support.

Dual Metal GPU Rendering on 2015 Macbook Pro

For a laptop to offer dual GPU rendering, this is a big deal. You can render on both the AMD and Intel Iris Pro GPUs at the same time.

You could do this too on El Capitan, but the AMD Metal drivers are much faster on Sierra.

Dual Metal GPU Rendering on 2013 Mac Pro

This works very well.  Rendering video animations on this Mac is very fast.

Dual OpenCL rendering is not recommended due to a critical kernel dispatching bug present in recent versions of Mac OS. (Metal does not have this bug.)

Score:  Kickass with Caveats

Apple has clearly made a big effort to improve the Metal compute drivers for Sierra. OpenCL drivers (which had so many issues in EL Capitan) now seem to work as well as they did with Mac OS Yosemite.

Apple engineers actually found the cause of a bug preventing Metal rendering from working on Intel GPUs. We found the cause of a core bug in Metal preventing Metal Rendering on AMD/Nvidia. Hopefully, this collaboration can continue so Apple can achieve 100% rock solid GPU compute platform across all of its Mac configurations.

Probably 90% of Macs released in the last 3 years can now  use GPU rendering –( that is a guesstimate since we have no means to actually test 100 different Mac model configurations). This is a huge improvement over the El Capitan release, when we estimated then that only 30% of Macs could use GPU rendering.

We found issues on Sierra only with older Intel GPUs (i.e. 2013 Macbook Air). Workaround: Stay on El Capitan for now.

Intel CPU rendering has always worked. But when you can get 10x  faster rendering on a laptop with Metal, who wants to use CPU rendering ?

Meeting with Matt Feemster

Matt Feemster is the author of Fractorium, a GPU accelerated flame fractal renderer for Windows and Ubuntu Linux.

My son and I attended Nvidia’s CUDA conference and got to meet Matt since he lives in the Bay Area too.

The 3 Amigos – the only people on Planet Earth that have released apps that support GPU flame fractal rendering to date.

Left: Steven Brodhead Jr   – author of Flam4
Center: Steven Brodhead – author of Fractal Architect
Right: Matt Feemster         – author of Fractorium


Fractal Architect 4 Version 4.4 – Metal Rendering on AMD + Nvidia

This release is almost ready.

I figured out how to workaround a key Apple Metal bug and now Metal rendering works on AMD and Nvidia GPUs too! With Mac OS Sierra, the Metal rendering has great performance.

Metal can render on 2 GPUs at the same time. For instance, the 2013 Mac Pro with its twin GPUs renders almost twice as fast.

You can also combine rendering using both Intel Iris Pro and AMD GPUs on a 2015 Macbook Pro. Tested on Mac OS El Capitan 10.11.6.

Both GPUs: 159.75 Mips      8.5X
AMD:                93.14 Mips       4.9X
Intel Iris Pro: 84.64 Mips       4.5X
CUP (4 core): 18.84 Mips      1X

Bug Fix: Fixed image gamma for Resume renders (restart render to add higher quality)

Metal Rendering on Intel, AMD, & Nvidia GPUs Works!

Sierra Metal is Working Well on AMD and Nvidia

With Sierra coming out shortly, Metal renders can be made on all 3 GPU platforms: Intel, AMD, and Nvidia using Fractal Architect 4 version 4.4.0.

Apple has done a very good job on the Sierra release. In general, Metal is working well, and for some older GPUs, OpenCL rendering now works again (El Capitan’s OpenCL drivers were so broken).

Both Mac OS El Capitan and Sierra support Metal rendering, but the quality of the Metal drivers varies depends on the specific GPU configuration and OS version used.

For example, on Sierra the AMD drivers are much faster than on El Capitan.

On 2013 Mac Pro, with 2 AMD GPUs, you can use both GPUs for even more speed using Metal (but OpenCL driver has a critical bug preventing usage of more than 1 GPU).

Warning – Sierra Metal may not work on your GPU

On El Capitan, my 2013 Macbook Air renders 10.5 X faster than CPU. On Sierra, the Metal compiler cannot compile the app’s kernels on the 2013 Macbook Air, resulting in no GPU rendering at all !

But 2015 Intel Iris Pro in Macbook Pro works great with Metal !

Evaluating Sierra First

Since GPU compatibility is so hit and miss, I recommend installing Sierra first on an external hard drive and trying it out on your Mac(s).

You boot off that external drive by holding down the Option key at boot and select the external drive from the list shown at boot time.

Since normal hard drives are so SLOW, I recommend the following external drive: Samsung 250 GB T3 Portable SSD. This has worked very well for me, and the cost is reasonable.

Evaluate both OpenCL and Metal

Apple’s OpenCL drivers have been very good on AMD GPUs, but don’t work at all on Intel GPUs. But that OpenCL on AMD, may be faster than Metal on AMD. So remember to try both to see what works better.

Intel GPU Rendering now works on all Macs since 2012

This is BIG News !

Fractal Architect 4  now fully supports Metal GPU rendering on all Macs built since 2012 (using the Mac’s Intel GPU). Version 4.3.3 of FA 4 has some critical fixes.

Last October, we reported issues with Metal rendering. Those issues have been resolved in version 4.3.3 of Fractal Architect 4.

With the latest Sierra Beta, OpenCL GPU rendering now works on Intel GPUs for the first time too.

The rendering performance increase is HUGE.

El Capitan 10.11.6  Performance using Intel Metal

2013 Macbook Air     10.5 X faster than CPU
2015 Macbook Pro      4.8 X faster than CPU

Fractaling Across the Universe