Re: Shadows = Red Square (???)

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Angus Dorbie (dorbie++at++sgi.com)
Fri, 23 Apr 1999 15:25:36 -0700

Jorge Valencia Loera wrote:
>
> Hi pf`s,
>
> I hope somebody can help me with these problems:
>
> (Even if you`re not sure if it`ll work, send me your ideas, thanks)
> I use pf 2.2 on RE2:
>
> I am currently adding the shadowing functionality to an existing
> application using pf built-in shadowing (shadow map) and I am having
> some strange anomalies appearing on my screens.
>
> 1. When I change the properties of the lights in my application in
> order to cast shadows, a red square about 1/8 the size of my screen
> appears on the lower left corner and there is no way to get rid of
> it!!! I have no idea of what it is BUT I`ve seen that if I increase my
> shadow map size the red square gets bigger too (??????). It is not an
> object of my scene and wherever my viewpoint position is, it always
> appears on the lower left corner.
> ALSO I`ve seen that if I move my viewpoint position in order to
> have an object in front of it (it = the square), the red square will
> be hidden by my object as if it was part of the background.... (???)
> If I move back the viewpoint, the square reappears

Sounds like the depth map channel is causing problems.

Strange, I'm thinking overlay planes, callbacks or strange clear
functions but it's difficult to figure what the problem might be from
here.

>
> 2. I`ve seen that also when I enable the shadows my scene gets
> brighter than it is without shadows, that makes parts of my scene
> completly saturated by WHITE pixels. (???) [too much light]
> I know that I can modify the intensity of each light to avoid that
> behavior but without shadows the intensity of my pfLightSources is OK.
> Does pf needs a higher intensity to cast shadows?
> Should I need to modify the attributes of my lights each time I enable
> & disable shadowing? (that`s something that will happen often in my
> simulation).

This will be fixed in the latest eoe. The multipass stuff was broken and
shadows was part of that problem.

>
> 3. The project I'm working on has two main parts (almost totally
> independent), the computation of all the different parts of the
> simulation (dynamics, GUI, ...) & the visual renderer (pf based)
> representing visually the state of the simulation. We are able to run
> the simulation with or without the visuals.
> When I load my simulation with the visuals for the first time,
> everything is OK (the shadows are casted correctly on all my textured
> objects) but if I unload the visuals (only the visuals, the other part
> keeps running) and reload it some minutes after, the shadows will only
> appear on some textures & won`t appear anymore on other textures (none
> of my objects or lights have moved! so the scene should be the same!!)
> It is really strange because a shadow can completly cover an object
> before I kill my visuals, but when I re-run my visuals the same shadow
> appears on parts of the object and doesn`t appear on other parts of
> the same object (the only difference between the parts is the
> texture).
> HINT: If I wait about 30-40 minutes before I load my visuals again
> everything is OK.

This sounds like your programs IPC.

How do you communicate with your performer app?

Cheers,ANgus.

-- 
"Microsoft's system was like a forest that hadn't had a controlled
 burn in decades, just waiting for one person with a match to turn
 it into a disaster. Melissa was Microsoft's fault. They left their
 system wide open to this sort of abuse, they knew it could happen
 and did nothing." -- Bruce Perens


For advanced 3D graphics Performer + OpenGL based examples and tutors:
http://www.dorbie.com/

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