View Full Version : OpenGL vs DirectX ??

02-03-2003, 08:28 PM
Dear all,

A few years ago, I posted a request to ask which graphics library was the best between OpenGl and

Of course, this was application-dependant.

We were (and still are!) performing 3D scientifical visualization modelling of anatomical surfaces
and rendering resolution is of importance. Process speed also, but not like in the game

The answers I received where unanimous: go for OpenGL (and that is what we did).

I am sending this email for the following reasons: we are planning to start a collaboration with
some computer programming people
who are extensively using DirectX (very limited experience with OpenGL).

Of course they are pushing that the work would be performed using DirectX ... while I feel OpenGL
is still superior.

I am forwarding their answers to my concerns (see below). Clearly things moved lately and DirectX
seems to have progressed ...

I stopped programming myselve a while ago, and I do not feel I am still aware of the last
developments on that particular questions ...

Can somebody give us some advices on that ?

Thank you VERY much in advance !!!!!!!!!


------- Start of forwarded message -------

> PS: I know that you develop your program using DirectX, while
> (at least when I was still programming) OpenGl was generaly
> acknowledged to be superior for scientifical application
> where resolution is of importance, while DirectX was more
> suitable for games (where resolution is usually lower). Are
> you certain that DirectX is the best choice for our
> application ? As you know realistic visualisation is of
> importance for us, so we need to choose the best ...

There are a lot of internet sources comparing OpenGL and DirectX:

The summary table chart:

This chart is rather good but "Software Emulation of Unaccelerated Features"
is fully present in DirectX via selectring reference rasterizer device.

A good article to read:

So reasons why i've chosen DirectX:
1. It is generally faster since it is more hardware dependant.
2. It supports more rendering features
3. It supports the fastest general vertex format ever: nonindexed triangle
strip in native way.
4. It has better documentation. (Subjective judgment)
5. I'm neither not working with non windows platforms nor aiming them in
6. It has more general features. It is possible to perform very fast
"visual" hull collision in directX via vertex&pixel shader technique even
for nonconvex hulls. Not yet implemented and still not planned in nearest
future, but nevertheless.
7. It have some nifty embedded features besides D3D like Direct Input and so
on, which allow my tool to support almost any external device for input
(just stub into future)

>OpenGl was generaly acknowledged to be superior for scientifical application

Not exactly. The OpenGl have a great compatibility, so if you are aiming for
workstations with no directX, the OpenGl is the only exit.

------- End of forwarded message -------


Associate Professor, Marie Curie Fellow
Department of Anatomy (CP 619)
University of Brussels (ULB)
Lennik Street 808
1070 Brussels - Belgium
Phone: +32-2-555-6325 (-6376)
Fax: +32-2-555-6378
Email: sintjans@ulb.ac.be
LAB website: http://homepages.ulb.ac.be/~anatemb
VAKHUM project coordinator: http://www.ulb.ac.be/project/vakhum

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