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最新推荐文章于 2023-11-10 13:40:19 发布

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本文介绍了如何在osg中实现自定义事件处理器，包括处理不同类型的事件，以及如何在视图中添加和移除事件处理器。此外，还详细讲解了物体相交的步骤，包括使用IntersectionVisitor进行相交检查和获取相交信息。最后，探讨了图形上下文的创建和使用。

自定义事件处理器

osgGA::GUIEventHandler 事件处理器/事件遍历器的回调
- 重载
  - handle
    - 参数osgGA::GUIEventAdapter
      - getEventType
      - getModKeyMask 返回MODKEY_CTRL/MODKEY_SHIFT/MODKEY_ALT
      - 注意：相应set方法不适合在handle中出现，用于osg底层显示系统向事件队列添加事件
    - 参数osgGA::GUIActionAdapter
      - osgViewer::Viewer* viewer = dynamic_castosgViewer::Viewer*(&aa);
事件处理管理
- addEventHandler
- removeEventHandler
步骤
- 自定义事件处理器
- viewer中加入自定义事件处理器
- 取消viewer主相机控制器
  - viewer.getCamera()->setAllowEventFocus(false);
- 设置viewer的ViewMatrix
  - viewer.getCamera()->setViewMatrixAsLookAt(osg::Vec3(0.0f,-100.0f,0.0f), osg::Vec3(), osg::Z_AXIS );

示例

#include <osg/MatrixTransform>
#include <osgDB/ReadFile>
#include <osgGA/GUIEventHandler>
#include <osgViewer/Viewer>

class ModelController : public osgGA::GUIEventHandler
{
public:
	ModelController(osg::MatrixTransform* node)
		: _model(node)
	{}
	virtual bool handle(const osgGA::GUIEventAdapter& ea,
		osgGA::GUIActionAdapter& aa);

protected:
	osg::ref_ptr<osg::MatrixTransform> _model;
};
bool ModelController::handle(const osgGA::GUIEventAdapter& ea,
	osgGA::GUIActionAdapter& aa)
{
	if (!_model) return false;
	osg::Matrix matrix = _model->getMatrix();

	switch (ea.getEventType())
	{
	case osgGA::GUIEventAdapter::KEYDOWN:
		switch (ea.getKey())
		{
		case 'a': case 'A':
			matrix *= osg::Matrix::rotate(-0.1f, osg::Z_AXIS);
			break;
		case 'd': case 'D':
			matrix *= osg::Matrix::rotate(0.1f, osg::Z_AXIS);
			break;
		case 'w': case 'W':
			matrix *= osg::Matrix::rotate(-0.1f, osg::X_AXIS);
			break;
		case 's': case 'S':
			matrix *= osg::Matrix::rotate(0.1f, osg::X_AXIS);
			break;
		default:break;
		}
		_model->setMatrix(matrix);
		break;
	default:
		break;
	}
	return false;
}
int main(int argc, char** argv)
{
	osg::ref_ptr<osg::Node> model = osgDB::readNodeFile("cessna.osg");
	osg::ref_ptr<osg::MatrixTransform> mt = new osg::MatrixTransform;
	mt->addChild(model.get());
	osg::ref_ptr<osg::Group> root = new osg::Group;
	root->addChild(mt.get());

	osg::ref_ptr<ModelController> ctrler =
		new ModelController(mt.get());
	osgViewer::Viewer viewer;
	viewer.addEventHandler(ctrler.get());
	viewer.getCamera()->setAllowEventFocus(false);
	viewer.getCamera()->setViewMatrixAsLookAt(
		osg::Vec3(0.0f, -100.0f, 0.0f), osg::Vec3(), osg::Z_AXIS);

	viewer.setSceneData(root.get());
	return viewer.run();
}

自定义事件

osgGA::EventQueue
- addEvent
  - osgGA::GUIEventAdapter
    - setEventType
    - setButton
- userEvent
  - 参数为osg::Referenced
说明：每一个事件都将遍历事件处理器

示例

#include <osg/Switch>
#include <osgDB/ReadFile>
#include <osgGA/GUIEventHandler>
#include <osgViewer/Viewer>
#include <iostream>

struct TimerInfo : public osg::Referenced
{
	TimerInfo(unsigned int c) : _count(c) {}
	unsigned int _count;
};
class TimerHandler : public osgGA::GUIEventHandler
{
public:
	TimerHandler(osg::Switch* sw) : _switch(sw), _count(0) {}
	virtual bool handle(const osgGA::GUIEventAdapter& ea,
		osgGA::GUIActionAdapter& aa);

protected:
	osg::ref_ptr<osg::Switch> _switch;
	unsigned int _count;
};
bool TimerHandler::handle(const osgGA::GUIEventAdapter& ea,
	osgGA::GUIActionAdapter& aa)
{
	switch (ea.getEventType())
	{
	case osgGA::GUIEventAdapter::FRAME:
		if (_count % 100 == 0)
		{
			osgViewer::Viewer* viewer =
				dynamic_cast<osgViewer::Viewer*>(&aa);
			if (viewer)
			{
				viewer->getEventQueue()->userEvent(
					new TimerInfo(_count));
			}
		}
		_count++;
		break;
	case osgGA::GUIEventAdapter::USER:
		if (_switch.valid())
		{
			const TimerInfo* ti =
				dynamic_cast<const TimerInfo*>(ea.getUserData()
					);
			std::cout << "Timer event at: " << ti->_count <<
				std::endl;

			_switch->setValue(0, !_switch->getValue(0));
			_switch->setValue(1, !_switch->getValue(1));
		}
		break;
	default:
		break;
	}
	return false;
}
int main(int argc, char** argv)
{
	osg::ref_ptr<osg::Node> model1 = osgDB::readNodeFile("cessna.osg");
	osg::ref_ptr<osg::Node> model2 = osgDB::readNodeFile("cessnafire.osg");
	osg::ref_ptr<osg::Switch> root = new osg::Switch;
	root->addChild(model1.get(), false);
	root->addChild(model2.get(), true);
	osgViewer::Viewer viewer;
	viewer.setSceneData(root.get());
	viewer.addEventHandler(new TimerHandler(root.get()));
	return viewer.run();
}

物体相交

osgUtil::IntersectionVisitor
- 继承osg::NodeVisitor
- 参数为osgUtil::Intersector

步骤

定义自定义事件处理器
- 定义intersector
  - osg::ref_ptrosgUtil::LineSegmentIntersector intersector = new osgUtil::LineSegmentIntersector(osgUtil::Intersector::WINDOW, ea.getX(), ea.getY());
- 遍历
  - osgUtil::IntersectionVisitor iv( intersector.get() );
  - camera->accept( iv );
- 检查相交
  - containsIntersections
- 获取相交
  - getIntersections 由近到远
- 获取相交点
  - getLocalIntersectPoint
  - getWorldIntersectPoint
- 获取相交几何体及父节点
- 获取相交三角组元索引
- …

示例

#include <osg/MatrixTransform>
#include <osg/ShapeDrawable>
#include <osg/PolygonMode>
#include <osgDB/ReadFile>
#include <osgUtil/LineSegmentIntersector>
#include <osgViewer/Viewer>

class PickHandler : public osgGA::GUIEventHandler
{
public:
	osg::Node* getOrCreateSelectionBox();
	virtual bool handle(const osgGA::GUIEventAdapter& ea,
		osgGA::GUIActionAdapter& aa);

protected:
	osg::ref_ptr<osg::MatrixTransform> _selectionBox;
};
osg::Node* PickHandler::getOrCreateSelectionBox()
{
	if (!_selectionBox)
	{
		osg::ref_ptr<osg::Geode> geode = new osg::Geode;
		geode->addDrawable(
			new osg::ShapeDrawable(new osg::Box(osg::Vec3(),
				1.0f)));


		_selectionBox = new osg::MatrixTransform;
		_selectionBox->setNodeMask(0x1);
		_selectionBox->addChild(geode.get());


		osg::StateSet* ss = _selectionBox->getOrCreateStateSet();
		ss->setMode(GL_LIGHTING, osg::StateAttribute::OFF);
		ss->setAttributeAndModes(new osg::PolygonMode(osg::PolygonMode::FRONT_AND_BACK, osg::PolygonMode::LINE));
	}
	return _selectionBox.get();
}
bool PickHandler::handle(const osgGA::GUIEventAdapter& ea,
	osgGA::GUIActionAdapter& aa)
{
	if (ea.getEventType() != osgGA::GUIEventAdapter::RELEASE || ea.getButton() != osgGA::GUIEventAdapter::LEFT_MOUSE_BUTTON
		||
		!(ea.getModKeyMask()&osgGA::GUIEventAdapter::MODKEY_CTRL)
		)
		return false;


	osgViewer::Viewer* viewer =
		dynamic_cast<osgViewer::Viewer*>(&aa);
	if (viewer)
	{
		osg::ref_ptr<osgUtil::LineSegmentIntersector>
			intersector =
			new osgUtil::LineSegmentIntersector(
				osgUtil::Intersector::WINDOW, ea.getX(), ea.getY()
			);
		osgUtil::IntersectionVisitor iv(intersector.get());
		iv.setTraversalMask(~0x1);
		viewer->getCamera()->accept(iv);

		if (intersector->containsIntersections())
		{
			osgUtil::LineSegmentIntersector::Intersection result = *(intersector->getIntersections().begin());
			osg::BoundingBox bb = result.drawable->getBoundingBox();
			osg::Vec3 worldCenter = bb.center() * osg::computeLocalToWorld(result.nodePath);
			_selectionBox->setMatrix(
				osg::Matrix::scale(bb.xMax() - bb.xMin(),
					bb.yMax() - bb.yMin(),
					bb.zMax() - bb.zMin()) *
				osg::Matrix::translate(worldCenter));
		}
	}
	return false;
}
int main(int argc, char** argv)
{
	osg::ref_ptr<osg::Node> model1 = osgDB::readNodeFile("cessna.osg");
	osg::ref_ptr<osg::Node> model2 = osgDB::readNodeFile("cow.osg");
	osg::ref_ptr<osg::Group> root = new osg::Group;
	root->addChild(model1.get());
	root->addChild(model2.get());

	osg::ref_ptr<PickHandler> picker = new PickHandler;
	root->addChild(picker->getOrCreateSelectionBox());

	osgViewer::Viewer viewer;
	viewer.setSceneData(root.get());
	viewer.addEventHandler(picker.get());
	return viewer.run();
}

图形上下文

形式
- 相关的窗口API
- 缓冲，比如opengl的像素缓冲
osg
- osg::GraphicsContext
  - createGraphicsContext()
    - 参数为osg::GraphicsContext::Traits
- osgViewer::GraphicsWindow
  - getEventQueue() 处理GUI事件
步骤
- 创建traits
- 创建graphics context
- 附加到相机
- 设置相机为主相机

示例

#include <osg/GraphicsContext>
#include <osgDB/ReadFile>
#include <osgViewer/Viewer>


int main(int argc, char** argv)
{
	osg::ref_ptr<osg::GraphicsContext::Traits> traits =
		new osg::GraphicsContext::Traits;
	traits->x = 50;
	traits->y = 50;
	traits->width = 800;
	traits->height = 600;
	traits->windowDecoration = true;
	traits->doubleBuffer = true;
	traits->samples = 4;

	osg::ref_ptr<osg::GraphicsContext> gc =
		osg::GraphicsContext::createGraphicsContext(traits.get());

	osg::ref_ptr<osg::Camera> camera = new osg::Camera;
	camera->setGraphicsContext(gc);
	camera->setViewport(
		new osg::Viewport(0, 0, traits->width, traits->height));
	camera->setClearMask(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT);
	camera->setClearColor(osg::Vec4f(0.2f, 0.2f, 0.4f, 1.0f));
	camera->setProjectionMatrixAsPerspective(
		30.0f, (double)traits->width / (double)traits->height,
		1.0, 1000.0);

	osg::ref_ptr<osg::Node> root = osgDB::readNodeFile(
		"cessna.osg");

	osgViewer::Viewer viewer;
	viewer.setCamera(camera.get());
	viewer.setSceneData(root.get());
	return viewer.run();
}