
Why Geometry Shaders Are Slow (Unless You’re Intel) - mxfh
http://www.joshbarczak.com/blog/?p=667
======
westoncb
I was working on a problem recently that's remarkably similar the author's
rendering of hundreds of thousands of cubes (each arbitrarily oriented in
space), and looked into geometry shaders some. There were several points where
I thought I'd be able to use them to implement some resource saving trick that
occurred to me—but was discouraged by further reading each time.

I guess there are uses out there that they're more ideally suited for, but
it'd be great if they did what they do... only fast :)

Now I'm excited about this, though
([https://www.khronos.org/vulkan)—which](https://www.khronos.org/vulkan\)—which)
I only noticed through the author's blog.

~~~
frozenport
Ugg! Graphics and GPU compute were split by choice because OpenGL programming
is an esoteric art, the only thing that can fix these is simplification -
something I don't trust Khronos with because of my miserable experience with
OpenCL when compared to CUDA.

~~~
greggman
Let's hope that since they had input from Value, Epic, and other users of the
API instead of just producers they are doing a better job then they did with
OpenCL.

~~~
wlesieutre
From what I've heard, Vulkan is largely based on Mantle.

And while Khronos hasn't released anything unless you're a member of the
secret club, you can take a look at Mantle here: [http://www.amd.com/en-
us/innovations/software-technologies/t...](http://www.amd.com/en-
us/innovations/software-technologies/technologies-gaming/mantle#downloads)

------
bjwbell
Does anyone know of a real world game or app that uses geometry shaders?

Everything I've read (including this) says they're good in theory but not so
much in practice.

~~~
malkia
Assasin's Creed mentions of Geometry Shaders being used - (March, 2014, GDC) -
[https://bartwronski.files.wordpress.com/2014/03/ac4_gdc.pdf](https://bartwronski.files.wordpress.com/2014/03/ac4_gdc.pdf)

possibly many others.

EDIT: Here is much more updated version (4 versions actually with much more
detailed images/video and more notes) - from the author's web-page -
[http://bartwronski.com/2014/05/09/digital-
dragons-2014-slide...](http://bartwronski.com/2014/05/09/digital-
dragons-2014-slides/)

oh, and if you are looking for some fun graphics failures :)

[http://igetyourfail.blogspot.com/2009/02/behold-power-of-
geo...](http://igetyourfail.blogspot.com/2009/02/behold-power-of-geometry-
shaders.html)

~~~
psykotic
For post-processing, Capcom's MT Framework used geometry shaders to generate
primitives in lieu of scattered read-modify-writes to pixels. I'm not sure if
the bang for the buck was there, but the concept was clever enough that it
stuck with me.

