Irrlicht Engine

Posted: **Thu Sep 16, 2010 8:07 pm**

Hi guys,

when I try to manually set the LOD of a patch with ITerrainSceneNode::SetLODOfPatch, then you can see the patch is flickering. For me it looks like that the terrain updates the LOD level of an patch after I set it and then I set it again and so on.
So is there a way to prevent this or to tell the terrain that a specific patch shouldn't be updated?

Thanks,
-Lu

Posted: **Sun Sep 19, 2010 12:28 pm**

Sorry for the double post, but here's a minimal code and a video for the problem

Link to the video

The code:

Code: Select all

#include "irrlicht.h"

#pragma comment(lib,"irrlicht.lib")

using namespace irr;



int main()
{
    //create device,sgmr and driver
    IrrlichtDevice * device = createDevice(video::EDT_OPENGL);
    scene::ISceneManager * smgr = device->getSceneManager();
    video::IVideoDriver * driver = device->getVideoDriver();

    //create camera
    scene::ICameraSceneNode * camera = smgr->addCameraSceneNodeFPS(); 


    //create a heightmap
    video::IImage * heightmap = driver->createImage(video::ECF_R8G8B8,core::dimension2d<u32>(65,65));
    for(int x=0;x<65;++x)
        for(int y=0;y<65;++y)
            heightmap->setPixel(x,y,video::SColor(255,(sin(float(x+y))+1)*122+1,(sin(float(x+y))+1)*122+1,(sin(float(x+y))+1)*122+1),false);
    driver->writeImageToFile(heightmap,"heightmap.png",0);
    heightmap->drop();
    heightmap = 0;

    //create terrain
    scene::ITerrainSceneNode * terrain = smgr->addTerrainSceneNode("heightmap.png",0,-1,core::vector3df(0,-50,0),core::vector3df(),core::vector3df(10,0.1,10));
    terrain->setMaterialFlag(video::EMF_WIREFRAME,true);


    //set ambient light
    smgr->setAmbientLight(video::SColorf(1.0,1.0,1.0,1.0));

    //run
    while(device->run())
    {
        //set patch lod ==> flickering
        terrain->setLODOfPatch(0,0,3);

        //draw
        driver->beginScene();
        smgr->drawAll();
        driver->endScene();
    }


    return 0;
}

Posted: **Sun Sep 19, 2010 3:22 pm**

Looks like a bug, I'll move it to the bug forum and investigate further.

Posted: **Mon Sep 20, 2010 8:07 pm**

Thanks for moving this topic hybrid.

I took a short look in the source and for me it seems, that if the camera moved or rotated by a certain value (set with ITerrainSceneNode::setCameraMovementDelta or the equivalent for the rotation), the geo data gets updated.
So maybe there must be a flag which indicats if the LOD was manually set and then don't change the LOD state of this patch but clear the flag (I Don't know really how to explain it, so I hope that this was understandable

).
Well I try if I can do this myself and if I'm successful, post it here.

-Lu

Irrlicht Engine

Patch flickering when manually setting the LOD

Patch flickering when manually setting the LOD