topic Re: OpenGL-problems in Visualization

OpenGL-problems

KeesW — Thu, 11 May 2023 13:58:54 GMT

Here is a strange happening. We're generating an axonometric of a large house. Works fine with the internal engine but with OpenGL, a couple of the roof slabs are missing and so is a portion of the floor. Is this likely to be an OpenGL bug, or a video card problem?

Also, a chap in our drawing office uses Revit. This has apparently been otimised for OpenGL and he says that it shows shadows. I was told that OpenGL has limitations and one of them is that it won't show shadows. Is that right? Or is this a (poor) Graphisoft implementation of OpenGL?

OpenGL default images are very dark. Is that normal?

Cornelis (Kees) Wegman
AC10, Windows XP Pro, 1GB RAM, NVidea FX 5200, 40GB HD (lots of space left on it)

Re: OpenGL-problems

Dwight — Sun, 23 Jul 2006 13:26:34 GMT

To test the OpenGL performance of your card, make the OpenGL view smaller.

As for the image being dark, the brightness of the scene is related to the light present in the scene - turn up your sun and ambient lights.

Re: OpenGL-problems

Dwight — Sun, 23 Jul 2006 13:27:30 GMT

Ooops.

As for shadows -

Yes, OpenGL can do transparency, shadows - the works.

And so it goes.

Re: OpenGL-problems

Link — Sun, 23 Jul 2006 21:56:45 GMT

KeesW wrote:
Works fine with the internal engine but with OpenGL, a couple of the roof slabs are missing and so is a portion of the floor. Is this likely to be an OpenGL bug, or a video card problem?

You may want to check your OpenGL options available from the 3D Windows Settings dialog. Maybe you have a transparent material applied to your roofs & slabs (unlikely), or parts of your model are being culled or incorrectly checked for occlusion(more likely). Not all OpenGL cards support Occlusion checking.

For more information, check p.105 of the ArchiCAD 10 New Features Guide, from your Help menu.

Or it could be an OpenGL bug, or a video card problem!

Dwight wrote:
Yes, OpenGL can do transparency, shadows - the works.

Shadows hey? You sure mate?

Cheers,
Link.

Re: OpenGL-problems

Dwight — Sun, 23 Jul 2006 22:05:30 GMT

Well, not in ArchiCAD, but the code allows for it.

And also transparency that we don't have in ArchiCAD.

SketchUp is a prime example of OpenGL shadow casting.

And here, for example, is one of many articles on the topic:

http://www.opengl.org/resources/code/samples/mjktips/rts/index.html

Re: OpenGL-problems

Link — Sun, 23 Jul 2006 22:13:10 GMT

Dwight wrote:
Well, not in ArchiCAD, but the code allows for it.

Graphisoft musn't have been willing to pay for that extra functionality!

Cheers,
Link.

Re: OpenGL-problems

Dwight — Sun, 23 Jul 2006 22:21:41 GMT

Shadow casting might be tricky, but lots of applications can implement transparency - and not just the on/off invisibility that we have.

OpenGL, with textures, transparency and shadow casting could supplant many of the occasions where we make a photo rendering - in seconds per frame.

Re: OpenGL-problems

__archiben — Sun, 23 Jul 2006 22:51:41 GMT

Dwight wrote:
Shadow casting might be tricky, but lots of applications can implement transparency - and not just the on/off invisibility that we have.

it's a really poor show that software as expensive as archicad is cannot implement openGL with the same degree of success as many smaller, cheaper applications can.

i had no idea openGL transparency could be anything other than on or off until i saw the great work pavol had made of it's implementation in 'archishock' . . . when someone can write an add-on for archicad that takes the archicad material data and turns out a far superior openGL implementation you have to wonder just how low graphisoft's internal standards might be don't you?!

~/archiben

Re: OpenGL-problems

KeesW — Sun, 23 Jul 2006 23:41:58 GMT

Thanks for your comments. So OpenGL will do shadows? Disappointing to find Graphisoft implement yet another slightly underdone application. AC is not a cut-price product - at least not for the purchaser.

I am becoming weary of having to constantly apologize for unnecessary shortcomings of Archicad - especially when talking to Revit users. They undoubtedly have other problems but at least their important add-ons appear to be complete. How about a patch from GS to bring our OpenGL upto scratch?

Kees

Re: OpenGL-problems

Anonymous — Tue, 25 Jul 2006 22:25:10 GMT

Do you want to know what the Mac can do with the right OpenGL code?

http://www.ati.com/developer/demos/macss2/index.html

Imagine if our archicad models could implement some of these features, at least go past the flat shading we currently look at, then shadows, then...

Re: OpenGL-problems

andrewzarb — Tue, 25 Jul 2006 23:30:36 GMT

Open Gl is a great language, just look at what games like Quake can do with it; transparency, reflections, shadows, lighting...

I remember playing on a SiliconGraphics Indigo in 1995, anyone remember those? Silicon Graphics wrote Open GL and their machines back then could show stuff ArchiCAD users only dream about.

Re: OpenGL-problems

KeesW — Sun, 06 Aug 2006 07:57:28 GMT

I have loaded Archicad 10 on a new home computer. Same problems with open-GL exist - ie some roofs not showing. Transparency settings are OK and occlusion I can't find. Reducing the size of the 3D window doesn't help. Roofs and slabs show correctly with internal 3D engine.

Both graphic cards are NVidea.

Strangly enough, changing the material does fix it. Settings of all roofs seem the same but new paramenters have been added in the floor plan and section parameter box of elements. Guess I'll just keep looking.

Re: OpenGL-problems

Ralph Wessel — Sun, 06 Aug 2006 19:32:45 GMT

Dwight wrote:
Ooops.
Yes, OpenGL can do transparency, shadows - the works.

OpenGL can render shadows, but it doesn't calculate them for you, i.e. it isn't as easy as just flicking a switch to turn on the shadows in OpenGL. ArchiCAD models can quickly generate a lot of polygons, and the time required to calculate shadows cast from them might be excessive. Consider the time ArchiCAD takes to calculate cast shadows for a section/elevation view.

Games shouldn't be compared to CAD because game engines and graphics are designed to work within a very narrow (highly optimised) context. I'm sure we will see shadows in ArchiCAD's 3D window at some time in the future though.

BTW, I've also seen roofs randomly disappearing in the 3D and/or section windows. They usually reappear if I edit the object in any way (or slightly move the section line. I haven't confirmed it yet, but it's my impression that it is usually roofs with a skylight inserted.

Re: OpenGL-problems

Dwight — Sun, 06 Aug 2006 19:43:34 GMT

Fair enough. But who cares if it takes a while to generate shadows? The advantages of an OpenGL shortcut to PhotoRendering are numerous.

If Archicad users could generate a shadow-casting OpenGL view with surface textures and window transparency, those features would represent a substantial quality improvement in design communication because:
1: OpenGL exists because it is fast(er), even when imaging shadows, and especially for fly-thrus where photoreal quality is always diminished and movement emphasized.
2: Almost all design decisions could be more attractively and more quickly shown - the lesson of SketchUp is that a pastel cartoon rendering like it makes is as good as a wink to a blind man.
3: The superficial nature of OpenGl helps disguise incomplete models - at a time when design decisions get made....