求交后高亮显示某个Drawable

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博客介绍了在3D场景中，如何通过求交算法找到点击位置对应的Drawable，并实现高亮显示。当点击发生时，创建一个Sphere Drawable并设置为绿色，用于标记高亮点。同时，提供了两种方式修改Drawable的颜色，一种是直接更改颜色数组，另一种是通过材质设置散射光。代码示例详细展示了具体操作步骤。

求交后高亮显示某个Drawable:

if (picker->containsIntersections())

{

osg::Vec3 ptWorldIntersectPointFirst= picker->getFirstIntersection().getWorldIntersectPoint();

cout<<"world coords vertex("<< ptWorldIntersectPointFirst.x()<<","

<< ptWorldIntersectPointFirst.y()<< ","<< ptWorldIntersectPointFirst.z()<<")"<< std::endl;

//高亮此点

double dPointRadius= 15.0f;

osg::ShapeDrawable* pShd= new osg::ShapeDrawable(

new osg::Sphere( ptWorldIntersectPointFirst, dPointRadius));

pShd->setColor( osg::Vec4( 0, 1, 0, 1));

geode->addDrawable( pShd);

////将此Drawable高亮显示(更改其材质－－散射光)

//osg::ref_ptr< osg::StateSet> pssDra= picker->getFirstIntersection().drawable->getOrCreateStateSet();

////改变颜色

//osg::Material* mat = dynamic_cast< osg::Material*>

// ( pssDra->getAttribute( osg::StateAttribute::MATERIAL));

//if ( mat == NULL)

//{

//mat = new osg::Material;

// mat->setDataVariance( osg::Object::DYNAMIC);

// pssDra->setAttribute( mat);

//}

//mat->setDiffuse( osg::Material::FRONT_AND_BACK, osg::Vec4( 1, 0, 0, 0));

//直接改变其颜色

osg::ref_ptr< osg::Geometry> pGmt= picker->getFirstIntersection().drawable->asGeometry();

if ( pGmt != NULL)

{

//颜色(先获取原始颜色数组，再调用dirty()更新)

osg::Vec4Array* pv4aColorsOld= dynamic_cast< osg::Vec4Array*> ( pGmt->getColorArray());

if ( pv4aColorsOld != NULL)

{

pv4aColorsOld->clear();

pv4aColorsOld->push_back( osg::Vec4( 1.0f, 0.0f, 0.0f, 1.0f) );//红色

pv4aColorsOld->dirty();//更新颜色数组

pGmt->getOrCreateStateSet()->setMode( GL_LIGHTING,osg::StateAttribute::OFF|

osg::StateAttribute::OVERRIDE);//关闭灯光

}

else

{

pv4aColorsOld= new osg::Vec4Array;

pv4aColorsOld->push_back( osg::Vec4( 1.0f, 0.0f, 0.0f, 1.0f) );//红色

pGmt->setColorArray( pv4aColorsOld);

pGmt->setColorBinding( osg::Geometry::BIND_OVERALL/*BIND_PER_PRIMITIVE_SET:*/);

pGmt->getOrCreateStateSet()->setMode( GL_LIGHTING,osg::StateAttribute::OFF|

osg::StateAttribute::OVERRIDE);//关闭灯光

}

注：要先获取颜色数组(getColorArray())，再更新(dirty())。如果调用Geometry ->setColorArray(…)来重新设置颜色数组，则会出错。

另一种方法是通过改变材质，但要开启光照，且高亮的颜色可能会随着光照而变化。

―――――――――――――――――――――――――

较完整代码如下：

bool CHUD_viewPoint::handle(const osgGA::GUIEventAdapter& ea,osgGA::GUIActionAdapter& aa)

{

switch(ea.getEventType())

{

case( osgGA::GUIEventAdapter::PUSH):

{

m_vPosWindowMouse.set( ea.getX(), ea.getY());//鼠标单击处的窗口坐标

osgViewer::Viewer* viewer = dynamic_cast< osgViewer::Viewer*>( &aa);

if (viewer)

{

UpdateText( viewer, ea);//更新文字信息

//主相机

osg::ref_ptr<osg::Camera> cameraMaster = viewer->getCamera();

osg::Matrix mvpw = cameraMaster->getViewMatrix() * cameraMaster->getProjectionMatrix();

if ( cameraMaster->getViewport()) mvpw.postMult( cameraMaster->getViewport()->computeWindowMatrix());

osg::Matrix _inverseMVPW;

_inverseMVPW.invert( mvpw);

osg::Vec3d nearPoint = osg::Vec3d( ea.getX(), ea.getY(), 0.0)* _inverseMVPW;//透视投影中Znear平面的交点

osg::Vec3d farPoint = osg::Vec3d( ea.getX(), ea.getY(), 1.0)* _inverseMVPW;//透视投影中Zfar平面的交点

////求交

//osg::ref_ptr< osgUtil::LineSegmentIntersector > picker = new osgUtil::LineSegmentIntersector(

// osgUtil::Intersector::WINDOW, ea.getX(), ea.getY());

//osgUtil::IntersectionVisitor iv( picker.get());

////g_grpMouse->getParent( 0)->getChild( 0)->accept( iv);//模型求交

//cameraMaster->accept( iv);//模型求交(从相机往下遍历)

//求交

osg::ref_ptr< osgUtil::LineSegmentIntersector > picker =new osgUtil::LineSegmentIntersector(

nearPoint, farPoint);//线段(真实的世界坐标)

osgUtil::IntersectionVisitor iv( picker.get());

//g_grpMouse->getParent( 0)->getChild( 0)->accept( iv);//模型求交/**/

g_grpMouse->getParent( 0)->getChild( 0)->/*asGroup()->getChild( 0)->*/accept( iv);//模型求交/**/

// 根节点 cow的MT节点

//cameraMaster->accept( iv);//模型求交(从相机往下遍历)

if (picker->containsIntersections())

{

osg::Vec3 ptWorldIntersectPointFirst= picker->getFirstIntersection().getWorldIntersectPoint();

cout<<"world coords vertex("<< ptWorldIntersectPointFirst.x()<<","

<< ptWorldIntersectPointFirst.y()<< ","<< ptWorldIntersectPointFirst.z()<<")"<< std::endl;

//高亮此点

double dPointRadius= 15.0f;

osg::ShapeDrawable* pShd= new osg::ShapeDrawable(

new osg::Sphere( ptWorldIntersectPointFirst, dPointRadius));

pShd->setColor( osg::Vec4( 0, 1, 0, 1));

geode->addDrawable( pShd);

////将此Drawable高亮显示(更改其材质－－散射光)

//osg::ref_ptr< osg::StateSet> pssDra= picker->getFirstIntersection().drawable->getOrCreateStateSet();

////改变颜色

//osg::Material* mat = dynamic_cast< osg::Material*>

// ( pssDra->getAttribute( osg::StateAttribute::MATERIAL));

//if ( mat == NULL)

//{

/// mat = new osg::Material;

// mat->setDataVariance( osg::Object::DYNAMIC);

// pssDra->setAttribute( mat);

//}

//mat->setDiffuse( osg::Material::FRONT_AND_BACK, osg::Vec4( 1, 0, 0, 0));

//直接改变其颜色

osg::ref_ptr< osg::Geometry> pGmt= picker->getFirstIntersection().drawable->asGeometry();

if ( pGmt != NULL)

{

//颜色(先获取原始颜色数组，再调用dirty()更新)

osg::Vec4Array* pv4aColorsOld= dynamic_cast< osg::Vec4Array*> ( pGmt->getColorArray());

if ( pv4aColorsOld != NULL)

{

pv4aColorsOld->clear();

pv4aColorsOld->push_back( osg::Vec4( 1.0f, 0.0f, 0.0f, 1.0f) );//红色

pv4aColorsOld->dirty();//更新颜色数组

pGmt->getOrCreateStateSet()->setMode( GL_LIGHTING,osg::StateAttribute::OFF|

osg::StateAttribute::OVERRIDE);//关闭灯光

}

else

{

pv4aColorsOld= new osg::Vec4Array;

pv4aColorsOld->push_back( osg::Vec4( 1.0f, 0.0f, 0.0f, 1.0f) );//红色

pGmt->setColorArray( pv4aColorsOld);

pGmt->setColorBinding( osg::Geometry::BIND_OVERALL/*BIND_PER_PRIMITIVE_SET:*/);

pGmt->getOrCreateStateSet()->setMode( GL_LIGHTING,osg::StateAttribute::OFF|

osg::StateAttribute::OVERRIDE);//关闭灯光

}

return true;

}

default:

return false;

}