[osg-users] Fwd: Strange osgShadow appearance of multiple models self-shadowing under a point light

[michael kapelko]

Hi.
I can't say anything about your specific problems, but I had wrong shadows
when small objects were outside larget objects, i.e. if there's a plane and
a ball, and ball is outside the plane, the shadows were sometimes wrong.
To test my assumption, you can add a model with a plane that is underneath
*everything* in the scene and a wall that is heigher than *everything* in
the scene.

2017-06-27 23:14 GMT+07:00 Bris Li <tqjxlm at gmail.com>:

> Hi all,
>
> It's a problem with osgShadow.
> I hava a scene with multiple pagedLOD models bundled in a group. The
> models are tiles of a city, and each tile is a single model (buildings are
> not separeted with terrain).
> I uses the code in the osgShadow example for shadowing, and put a point
> light in _shadowedScene. The models shadow on themselves.
>
> As the attached image shows, the shadow result is partially correct. In
> some particular angle range from the light source, the correct shadow is
> casted. But in the other range, shadow is not cast correctly, but some
> strange shadows appear which I guess is casted from the model at the other
> side.
> Also, if I put the light on one side of the building, the other side of it
> is still lit, no shadow showing.
> I have tried different shadow implementations, but the results remain
> almost the same.
>
> I can't figure out what is happening since the shadow is just 'partially'
> abnormal. Stuck here for days.
>
> Thanks.
>
> Regards,
> tqjxlm.
>
> osg version 3.4.0.
> code:
> ------------------------------------------------------------
> ------------------------------------------------------------
> ---------------------------------------------
> *Shadow*
>  // arguments
>  char* argv[] = {
> "--vdsm",
> "--positionalLight",
> "--ortho",
> "--parallel-split",
> "--num-sm",
> "4",
> "--cascaded"
> };
>
> int argc = sizeof(argv) / sizeof(argv[0]);
>
> // use an ArgumentParser object to manage the program arguments
> osg::ArgumentParser arguments(&argc, argv);
>
> // get the viewer
> osgViewer::View& viewer = getViewer();
>
> // init shadowed scene
> _shadowedScene = new osgShadow::ShadowedScene;
> osgShadow::ShadowSettings* settings = _shadowedScene->getShadowSettings();
> settings->setReceivesShadowTraversalMask(ReceivesShadowTraversalMask);
> settings->setCastsShadowTraversalMask(CastsShadowTraversalMask);
>
> double distance;
> if (arguments.read("--max-shadow-distance", distance))
> {
> settings->setMaximumShadowMapDistance(distance);
> }
>
> // choose shadow map implementation
> osg::ref_ptr<osgShadow::MinimalShadowMap> msm = NULL;
> if (arguments.read("--no-shadows"))
> {
> OSG_NOTICE << "Not using a ShadowTechnique" << std::endl;
> _shadowedScene->setShadowTechnique(0);
> }
> else if (arguments.read("--stsm"))
> {
> osg::ref_ptr<osgShadow::StandardShadowMap> st = new
> osgShadow::StandardShadowMap;
> _shadowedScene->setShadowTechnique(st.get());
> }
> else if (arguments.read("--pssm"))
> {
> int mapcount = 3;
> while (arguments.read("--mapcount", mapcount));
> osg::ref_ptr<osgShadow::ParallelSplitShadowMap> pssm = new
> osgShadow::ParallelSplitShadowMap(NULL, mapcount);
>
> int mapres = 1024;
> while (arguments.read("--mapres", mapres))
> pssm->setTextureResolution(mapres);
>
> while (arguments.read("--debug-color")) { pssm->setDebugColorOn(); }
>
>
> int minNearSplit = 0;
> while (arguments.read("--minNearSplit", minNearSplit))
> if (minNearSplit > 0) {
> pssm->setMinNearDistanceForSplits(minNearSplit);
> }
>
> int maxfardist = 0;
> while (arguments.read("--maxFarDist", maxfardist))
> if (maxfardist > 0) {
> pssm->setMaxFarDistance(maxfardist);
> std::cout << "ParallelSplitShadowMap : setMaxFarDistance(" << maxfardist
> << ")" << std::endl;
> }
>
> int moveVCamFactor = 0;
> while (arguments.read("--moveVCamFactor", moveVCamFactor))
> if (maxfardist > 0) {
> pssm->setMoveVCamBehindRCamFactor(moveVCamFactor);
> }
>
> double polyoffsetfactor = pssm->getPolygonOffset().x();
> double polyoffsetunit = pssm->getPolygonOffset().y();
> while (arguments.read("--PolyOffset-Factor", polyoffsetfactor));
> while (arguments.read("--PolyOffset-Unit", polyoffsetunit));
> pssm->setPolygonOffset(osg::Vec2(polyoffsetfactor, polyoffsetunit));
>
> _shadowedScene->setShadowTechnique(pssm.get());
> }
> else if (arguments.read("--ssm"))
> {
> osg::ref_ptr<osgShadow::SoftShadowMap> sm = new osgShadow::SoftShadowMap;
> _shadowedScene->setShadowTechnique(sm.get());
> }
> else if (arguments.read("--vdsm"))
> {
> while (arguments.read("--debugHUD")) settings->setDebugDraw(true);
> if (arguments.read("--persp")) settings->setShadowMapProjecti
> onHint(osgShadow::ShadowSettings::PERSPECTIVE_SHADOW_MAP);
> if (arguments.read("--ortho")) settings->setShadowMapProjecti
> onHint(osgShadow::ShadowSettings::ORTHOGRAPHIC_SHADOW_MAP);
>
> unsigned int unit = 1;
> if (arguments.read("--unit", unit)) settings->setBaseShadowTexture
> Unit(unit);
>
> double n = 0.0;
> if (arguments.read("-n", n)) settings->setMinimumShadowMapNearFarRatio(n);
>
> unsigned int numShadowMaps;
> if (arguments.read("--num-sm", numShadowMaps))
> settings->setNumShadowMapsPerLight(numShadowMaps);
>
> if (arguments.read("--parallel-split") || arguments.read("--ps"))
> settings->setMultipleShadowMapHint(osgShadow::ShadowSettings
> ::PARALLEL_SPLIT);
> if (arguments.read("--cascaded")) settings->setMultipleShadowMap
> Hint(osgShadow::ShadowSettings::CASCADED);
>
>
> int mapres = 1024;
> while (arguments.read("--mapres", mapres))
> settings->setTextureSize(osg::Vec2s(mapres, mapres));
>
> osg::ref_ptr<osgShadow::ViewDependentShadowMap> vdsm = new
> osgShadow::ViewDependentShadowMap;
> _shadowedScene->setShadowTechnique(vdsm.get());
> }
> else if (arguments.read("--lispsm"))
> {
> if (arguments.read("--ViewBounds"))
> msm = new osgShadow::LightSpacePerspectiveShadowMapVB;
> else if (arguments.read("--CullBounds"))
> msm = new osgShadow::LightSpacePerspectiveShadowMapCB;
> else // if( arguments.read( "--DrawBounds" ) ) // default
> msm = new osgShadow::LightSpacePerspectiveShadowMapDB;
> }
> else if (arguments.read("--msm"))
> {
> if (arguments.read("--ViewBounds"))
> msm = new osgShadow::MinimalShadowMap;
> else if (arguments.read("--CullBounds"))
> msm = new osgShadow::MinimalCullBoundsShadowMap;
> else // if( arguments.read( "--DrawBounds" ) ) // default
> msm = new osgShadow::MinimalDrawBoundsShadowMap;
> }
> else /* if (arguments.read("--sm")) */
> {
> osg::ref_ptr<osgShadow::ShadowMap> sm = new osgShadow::ShadowMap;
> _shadowedScene->setShadowTechnique(sm.get());
>
> int mapres = 1024;
> while (arguments.read("--mapres", mapres))
> sm->setTextureSize(osg::Vec2s(mapres, mapres));
> }
>
> if (msm)// Set common MSM & LISPSM arguments
> {
> _shadowedScene->setShadowTechnique(msm.get());
> while (arguments.read("--debugHUD")) msm->setDebugDraw(true);
>
> float minLightMargin = 10.f;
> float maxFarPlane = 0;
> unsigned int texSize = 1024;
> unsigned int baseTexUnit = 0;
> unsigned int shadowTexUnit = 1;
>
> while (arguments.read("--moveVCamFactor", minLightMargin));
> while (arguments.read("--minLightMargin", minLightMargin));
> while (arguments.read("--maxFarDist", maxFarPlane));
> while (arguments.read("--mapres", texSize));
> while (arguments.read("--baseTextureUnit", baseTexUnit));
> while (arguments.read("--shadowTextureUnit", shadowTexUnit));
>
> msm->setMinLightMargin(minLightMargin);
> msm->setMaxFarPlane(maxFarPlane);
> msm->setTextureSize(osg::Vec2s(texSize, texSize));
> msm->setShadowTextureCoordIndex(shadowTexUnit);
> msm->setShadowTextureUnit(shadowTexUnit);
> msm->setBaseTextureCoordIndex(baseTexUnit);
> msm->setBaseTextureUnit(baseTexUnit);
> }
>
> // init light
> osg::Vec4 lightpos(0.0, 0.0, 1, 0.0);
> bool spotlight = false;
> while (arguments.read("--positionalLight")) { lightpos.set(0.5, 0.5, 1.5,
> 1.0); }
> while (arguments.read("--directionalLight")) { lightpos.set(0.0, 0.0, 1,
> 0.0); }
> while (arguments.read("--spotLight")) { lightpos.set(0.5, 0.5, 1.5, 1.0);
> spotlight = true; }
>
>  // set light position, create a light ball for visualization
> osg::ref_ptr<osg::Geode> coord = createIndicator(_intersectedPoint);
> _lsIndicator = dynamic_cast<osg::ShapeDrawable*>(coord->getDrawable(0));
> _worldRoot->addChild(coord);
>
> _ls = new osg::LightSource;
> _ls->getLight()->setPosition(lightpos);
>  _ls->getLight()->setAmbient(osg::Vec4(0.7, 0.7, 0.7, 1.0));
>  _ls->getLight()->setDiffuse(osg::Vec4(0.8, 0.8, 0.8, 1.0));
>
> // set shadowed model
> _model = _loadedModels;
>  _nodeMask = _model->getNodeMask();
> _model->setNodeMask(_nodeMask | CastsShadowTraversalMask |
> ReceivesShadowTraversalMask);
>
> _shadowedScene->addChild(_model.get());
> _shadowedScene->addChild(_ls.get());
>
>  _root->addChild(_shadowedScene);
> ------------------------------------------------------------
> ------------------------------------------------------------
> ---------------------------------------------
> *View initialization*
> osg::StateSet* state = _root->getOrCreateStateSet();
> state->setMode(GL_DEPTH_TEST, osg::StateAttribute::ON);
>
> osg::ref_ptr<osgViewer::View> view = new osgViewer::View;
>
> osg::Camera* camera = view->getCamera();
> camera->setGraphicsContext( gw );
>
> const osg::GraphicsContext::Traits* traits = gw->getTraits();
>
> camera->setClearColor( osg::Vec4(1.0, 1.0, 1.0, 1.0) );
> camera->setViewport( new osg::Viewport(0, 0, traits->width,
> traits->height) );
> camera->setProjectionMatrixAsPerspective(
> 30.0f, static_cast<double>(traits->width)/static_cast<double>(traits->height),
> 0.1f, 100000.0f );
> camera->setComputeNearFarMode(osg::Camera::COMPUTE_NEAR_FAR_
> USING_BOUNDING_VOLUMES);
> camera->setNearFarRatio(0.000002);
> GLuint buffer = gw->getTraits()->doubleBuffer ? GL_BACK : GL_FRONT;
> camera->setReadBuffer(buffer);
> camera->setDrawBuffer(buffer);
>
> view->setSceneData( scene );
> view->addEventHandler(new osgViewer::StatsHandler);
> view->addEventHandler(new osgViewer::ThreadingHandler);
> view->addEventHandler(new osgViewer::WindowSizeHandler);
> view->addEventHandler(new osgViewer::LODScaleHandler);
> ------------------------------------------------------------
> ------------------------------------------------------------
> ---------------------------------------------
>
> And the screen shots:
>
> Strange shadow on a square.
>
>
>
> No shadow of the flag.
>
>
>
> Change light position, flag is shadowed correctly.
>
>
>
> Light on a build wall.
>
>
>
> The back side should not be lit.
>
>
> ​
>
>
> _______________________________________________
> osg-users mailing list
> osg-users at lists.openscenegraph.org
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>
>
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