shadow speckles

xDan · Post by **xDan** » Sat Apr 22, 2006 12:37 pm

Hi

My shadows have speckles in them

Almost like the model has lots of small holes in it which keep dissapearing and appearing.

How can I fix this?

Here's a screenshot:
http://www.freepgs.com/defilter/images/ ... eckles.png
the speckles change every frame. you'll have to copy the link to get it work

Thanks

hybrid · Post by **hybrid** » Sat Apr 22, 2006 1:02 pm

I guess it's zbuffer fighting. The terrain sometimes wins and is thus rendered in front of the shadow.

xDan · Post by **xDan** » Sat Apr 22, 2006 5:58 pm

Is there anything I can do? I tried making the zfar close (like 300).

The reason I moved to irrlicht was because I wanted easy shadows. Oh and particle effects. And normal mapping. And water.

xDan · Post by **xDan** » Tue Apr 25, 2006 3:49 pm

Let me try a different tack. Has anyone managed to get shadows working without these problems? Just, like, out of interest.

If not I guess shadows should be removed from irrlicht's feature list.

gfxstyler · Post by **gfxstyler** » Tue Apr 25, 2006 5:17 pm

yeah, i can enable them and they look just normal.

does your mesh have holes?

xDan · Post by **xDan** » Tue Apr 25, 2006 9:08 pm

no
I've googled z fighting and tried suggestions - larger znear, closer zfar but to no avail

is there a way in irrlicht to increase the zbuffer accuracy? and what is it by default?

a quote from a website: "glDepthFunc(GL_LEQUAL); // we put it again to LESS or EQUAL (or else you will get some z-fighting)"
*wonders if GL_LEQUAL is set*

although I suppose it must be all correct or other people would have problems.

hybrid · Post by **hybrid** » Tue Apr 25, 2006 9:29 pm

Code: Select all

$ grep -r GL_LEQUAL .
./COpenGLDriver.cpp:    glDepthFunc(GL_LEQUAL);
./COpenGLDriver.cpp:    glDepthFunc(GL_LEQUAL);
./COpenGLDriver.cpp:    glDepthFunc( GL_LEQUAL );

And no hits with GL_LESS. So at least not the wrong value is set

Did you try the same with DirectX? Spintz produced a fix for it to keep the FPU precision high if set to high in your settings. IIRC there is the possibility to have 16bit and 32bit zbuffer and Irrlicht usually reset it to 16bit without this fix. Maybe the same holds still for OpenGL in some occasions?

hybrid · Post by **hybrid** » Wed Apr 26, 2006 9:04 am

Another short update n this topic. The problem is easily reproducable: Start the SpecialFX example and turn on real-time shadows. You'll the the errors right behind the dwarf on the topmost step. At least for the unpatched irrlicht-1.0. I could not see this problem in irrlicht-0.14.
xDan, could you please try your app with 0.14? I'll check the source diff where the probably causes could lie.

xDan · Post by **xDan** » Wed Apr 26, 2006 8:32 pm

I'm using 0.14

I don't think I have it compiled for directx but I will find the libraries and try it...
maybe I will try out 1.0 as well.

hybrid · Post by **hybrid** » Wed Apr 26, 2006 8:42 pm

Darn, so it's not due to engine changes, but a longer term problem. The SpecialFX example changed textures and probably other things, so this might be the reason for appearance in the latest version.

xDan · Post by **xDan** » Wed Apr 26, 2006 9:28 pm

Looks the same with directx 8 or 9.
I will go have a look at irrlicht 1.0...

funcdoobiest · Post by **funcdoobiest** » Tue Oct 03, 2006 1:30 am

Any news on this, having the same problem with the character model: animated .X mesh, made in 3ds max, not sure which exporter the artist used, resaved in the DX model viewer.

Luke · Post by **Luke** » Tue Oct 03, 2006 11:27 am

Hybrid:

It may not be a problem with Irrlicht at all, the dwarf mesh has a gap under its head to save on polygons, its not visible unless you take the body away. Maybe someone skilled in modelling can fill it in and hopefully it will fix this.

Off topic:

Irrlicht’s shadow system is very limited (eg options in turn self shadowing off, what meshes receive shadows, etc) are there any future plans to improve this?

funcdoobiest · Post by **funcdoobiest** » Tue Oct 03, 2006 4:23 pm

^ I very much doubt it, if xDans problem is anything like mine, it appears that there are loads of TINY holes (like the size of a pixel) but I am certain it is not a problem with holes in the mesh, that is simply the easiest way to describe how it looks... and also the models I am using are all closed volumes.

bitplane · Post by **bitplane** » Tue Oct 03, 2006 5:54 pm

can you provide a screenshot? what's your graphics card? does it happen in OGL? can you provide a model file? is the recieving surface flat, or bumpy? does it only happen when the shadow is over certain type of material? have you tried the latest svn version of irrlicht?
if we can get enough info and a repeatable test case together this thread can be moved to bug reports.