Comments on: Ray Tracing: Shoot Before You Fly

By: Jack

Jack — Sat, 28 Aug 2010 22:29:45 +0000

Well said. Companies should achieve a good flight simulation engine first and then put an FPS into it later. I've been trying to get night looking good in Crysis Wars, but because of all the graphics and vis cheating, it looks HORRIBLE! Once you start trying to mess with Wars, you find out its really a load of crap and cheats. I really don't understand why it takes so much power to run, it must be really bad programming. And after seeing what is coming out in Crysis 2 which is aimed at consoles, that game looks even worse.

By: Anonymous

Anonymous — Thu, 08 Apr 2010 19:51:25 +0000

If these "tricks" were implemented in x-plane then fsx would have nothing left.
X-plane has made huge improvements lately and if it used shadow mapping and environment mapping i can only imagine how good it would look

By: Benjamin Supnik

Benjamin Supnik — Thu, 08 Apr 2010 13:23:05 +0000

Shadow mapping does correctly change the shadows with response to a change in light direction.

Shadow mapping _can_ cope with non-parallel light rays (think of a lamp casting light in all directions) or parallel (think of the sun - so far away, rays are nearly parallel).

Shadow mapping does not require authors to annotate or modify their content in any way.

Shadow mapping does NOT provide translucent shadows, so translucent windows tend to be a problem. Usually the best approach is to simply not shadow them.

I cannot comment on any future features in any future version of X-Plane.

By: Steve

Steve — Thu, 08 Apr 2010 13:09:33 +0000

Interesting. Does shadow mapping account for differences in light angle? Is it also something that the aircraft author would need to provide, or would X-Plane calculate the "volume?" Is this a possibility for XP 10?

By: Benjamin Supnik

Benjamin Supnik — Thu, 08 Apr 2010 12:53:25 +0000

"What sort of trick might work to simulate the sort of effect ray tracing provides in the way of self shadows?"

Shadow mapping.

http://en.wikipedia.org/wiki/Shadow_mapping

Stencil shadow volumes would also technically work

http://en.wikipedia.org/wiki/Shadow_volume

but shadow mapping has a number of advantages over stencil shadow volumes for a flight simulator.

By: Steve

Steve — Thu, 08 Apr 2010 12:49:05 +0000

What sort of trick might work to simulate the sort of effect ray tracing provides in the way of self shadows? Like the shadow that a high mounted wing will cast on the fuselage of an aircraft? Since most X-Plane flying happens at altitude, ray traced ground shadows are less useful than shadows on the aircraft. This might limit the amount of ray tracing needed, allowing for frame rate to remain high.

By: Benjamin Supnik

Benjamin Supnik — Wed, 07 Apr 2010 22:31:47 +0000

FS X is almost certainly using environment mapping.

http://en.wikipedia.org/wiki/Reflection_mapping

It's not ray tracing – it's a "trick". Tricks are good. Tricks mean 30 fps, not 0.3 fps. 🙂

By: Anonymous

Anonymous — Wed, 07 Apr 2010 22:26:21 +0000

do you have any idea what fsx uses?
on siny surfaces you can see reflections of trees sky and land. is this a form of ray tracing or just a visual trick?

By: Dan

Dan — Mon, 05 Apr 2010 07:32:54 +0000

What about atmospheric scattering? Is it just as taxing on the hardware as ray tracing?

By: Christer Hellholm

Christer Hellholm — Sun, 04 Apr 2010 15:01:04 +0000

I do hope that Laminar Research will at spare time create a new fork that is an X-Plane with OpenRT. When time is right (i.e. general hardware requirements and business model), Laminar can easily switch to X-Plane OpenRT fork. Like Apple did with Mac OS X PowerPC and Mac OS X Intel.

I know that Laminar Research do have limited resources, but test developing an OpenRT version at spare time shouldn't cost so much.The positive side effect is that you're building OpenRT competence.