Terrain Flicker

I am having an issue where groups of tiles will flicker. It looks as though they are switching between visible and not each frame. I took two screen shots to show what it looks like.

As you can see, even when the tiles that are flickering are visible, it doesn't fill in completely. Where should I begin looking for an answer to this issue?

Any shadow mode used?

Could you also post the terrain cfg file? And your computer specs?

I do use Additive Stencil Shadows. I am running it on a Dell XPS600 P4 3.56GHz with dual GeForce 6800's each having 256MB. Here is my terrain config file:GroupName=PLSM2

Width=4
Height=4

Data2DFormat=HeightField
LandScapeFileName=Cleveland

FileSystem=../Media/materials/textures

NumTextureFormatSupported=19

TextureFormatSupported0=Image
TextureFormatSupported1=BaseTexture
TextureFormatSupported2=Splatting
TextureFormatSupported3=Splatting5
TextureFormat=Image
ImageFilename=ClevelandTexture

ScaleX=15000
ScaleY=1000
ScaleZ=15000

Deformable=no
VertexCompression=yes
VertexProgramMorph=yes
VertexNormals=yes

NumMatHeightSplat=4
MaterialHeight1=15
MaterialHeight2=50
SplatFilename0=splatting_sand.png
SplatFilename1=splatting_grass.png
SplatFilename2=splatting_rock.png
SplatFilename3=splatting_snow.png

# where to put camera on load.
BaseCameraViewpoint.x=935.0f
BaseCameraViewpoint.y=24000.0f
BaseCameraViewpoint.z=-432.0f

Baselookat.x=0.0f
Baselookat.y=0.0f
Baselookat.z=0.0f

Might wanna try disabling stencil shadows and find out if that's the prob.

Nope, it still flickers, I am going to try going through and disabling things one by one and see if I can find it.

When I set VertexProgramMorph=no OR VertexCompression=no OR VertexNormals=no I get this error. But it goes away in some cases
-----------------------------------
Details:
-----------------------------------
Error #: -2005530516
Function: D3D9RenderSystem::_render
Description: Failed to DrawPrimitive : Invalid call.
File: ..\src\OgreD3D9RenderSystem.cpp
Line: 2458
Stack unwinding: <<beginning of stack>>

Here's what it doesVPM | VC | VN | Result
------------------------
no | no | no | works
no | no | yes | works
no | yes | no | error
no | yes | yes | error
yes | no | no | error
yes | no | yes | error
yes | yes | no | error
yes | yes | yes | works

But the combinations that work still flicker.

Are you sure you did disable shadows before new tests ?
Does demo using same terrain does that too ?
Does other texture mode give same results ?
Are you using multiples camera ?
CVS or SDK ?

I did disable shadows and it still flickered, so I enabled them again.
I can't run the PLSM demo, it keeps crashing with this error-----------------------------------
Details:
-----------------------------------
Error #: 7
Function: TextAreaOverlayElement::setFontName
Description: Could not find font BlueHighway.
File: ..\src\OgreTextAreaOverlayElement.cpp
Line: 337
Stack unwinding: <<beginning of stack>>
What do you mean by texture mode?
I only have 1 camera and I am using he CVS version of Ogre and the PLSM.

I will disable shadows and run through my previous tests again.

Ok, here's what I foundwhen I redid my tests with shadows disabled:VPM | VC | VN | Result
------------------------
no | no | no | works, Flickers
no | no | yes | works, Flickers
no | yes | no | error
no | yes | yes | error
yes | no | no | error
yes | no | yes | error
yes | yes | no | error
yes | yes | yes | works, Flickers

I got the same bluehighway error btw.

I went through the overlays and changed all occurances of BlueHighway to Arial and then added the arial.ttf file to the filesystem and it crashed with the same error, except it said Arial instead.

I commented out the overlay creation code..


//Overlay *o = OverlayManager::getSingleton().getByName( "PagingLandScape2/DebugOverlay" );
//o-> show();
//showDebugOverlay(true);


and then checked anywhere isVisible() was being called on the overlay and always returned false:



if ( false && OverlayManager::getSingleton().getByName( "PagingLandScape2/DebugOverlay" ) -> isVisible())



Ok, using your suggestions I got it to run and I pointed it at my cfg and everything and there was no flickering!

Well, that's sorta good news.

blue highway is ogre cvs font change (license problem), Ogre 1.2rc2 will not have any other font.

Anyone found out anything more on the problem (other than it just went away by itself)?

I got the same bad flickering problem. It seems the terrain segment that are rendered when the program start will be paged in/out correctly but everything outside that perimeter will either be paged out or will flickering on and off every frame.

It happens in my own code, not in the terrain viewer strangely. Well, I'll start back with the viewer and work my way down. If anyone did find out what causes that I'd appreciate to hear about it though. Would save me some searching

Cheers!

C.

I've found an explanation for my own blinking/flickering problem. I have 2 cameras in my scene. If both cameras are within range of a terrain section it will be on, if both cameras are out of range of a terrain section it will be off, if only 1 camera is within range of a terrain section it will blink/flicker. That's why I thought terrain sections that were originally loaded behaved properly : these tiles were always within range of camera 1.

Can you achieve to reproduce it in demo ?

Sorry for not getting back to you, it's been a busy weekend! But that was exactly the problem I had! I couldn't explain it as well as you though!

I had the main player camera and a second that I used as a "Minimap." I accidentally placed the minimap camera 200 units away from the player in the X direction and I had issues with flicker. When I was going through my code to try to track down the flickering, I noticed my error and fixed it along with moving some code around. Just general cleaning up and when I recompiled the flickering went away!

Ok, I can verify that the flicker is due to having multiple cameras looking at non-coincident areas of terrain. I have created an application that has a camera stationary at the top of a tower and another that the usre can move around. Once the user moves outside of the area that is covered my the stationary camera flickering occurs. It appears that the area covered my the intersection of the two cameras(fig 1.) is rendered properly, but the rest flickers.(fig 2, 3.) I guess what needs to be done is that the PLSM needs to render the union(fig 4.) of the terrain visible by all of the cameras. This shouldn't change the way that it acts with one camera, or with multiple in the same area, just with multiple that are spread out like in the example I showed.

Figure 1



Figure 2

The camera for the minimap is placed on a tower that you can see way in the back in the center of this pic.

Figure 3


Figure 4

thanks for the clear report.
I will try to reproduce and fix the bug.

Let me know of there is anything else that I can do to help!

fixed in cvs and source pack.

Incredible!! Thank you!!