说明
- OSG 入门看的，大佬绕道
- 示例来源于《OSG程序设计教程》
- 没有此电子书的小伙伴们，我已上传至CSDN
1. 多视口
- 程序功能：创建前后左右视图
#include <osgDB/ReadFile>
#include <osgViewer/Viewer>
#include <osgGA/TrackballManipulator>
#include <iostream>
// 创建前后左右视图
void CreateCamera(osgViewer::Viewer &viewer) {
// 系统接口。用来得到分辩率
osg::GraphicsContext::WindowingSystemInterface *wsi = osg::GraphicsContext::getWindowingSystemInterface();
// 窗口宽高
unsigned int width, height;
wsi->getScreenResolution(osg::GraphicsContext::ScreenIdentifier(0), width, height);
// 上下文关键参数
osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;
traits->x = 0;
traits->y = 0;
traits->width = width;
traits->height = height;
traits->windowDecoration = true;
traits->doubleBuffer = true;
traits->sharedContext = 0;
osg::ref_ptr<osg::GraphicsContext> gc = osg::GraphicsContext::createGraphicsContext(traits.get());
gc->setClearColor(osg::Vec4f(0.2f, 0.2f, 0.6f, 1.0f));
gc->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// 主视口
osg::ref_ptr<osg::Camera> cameraMaster = new osg::Camera;
cameraMaster->setGraphicsContext(gc.get());
// 相机视口设置
cameraMaster->setViewport(new osg::Viewport(traits->x, traits->y, traits->width, traits->height));
// 添加相机到VIEWER
viewer.addSlave(cameraMaster.get());
// 后视图
double aspectRatioScale = 1.0;
osg::ref_ptr<osg::Camera> camera = new osg::Camera;
// 设置上下文
camera->setGraphicsContext(gc.get());
// 设置后视图的窗口位置
camera->setViewport(new osg::Viewport(0, 0, width / 4, height / 4));
GLenum buffer = traits->doubleBuffer ? GL_BACK : GL_FRONT;
camera->setDrawBuffer(buffer);
camera->setReadBuffer(buffer);
// 添加相机到视口
viewer.addSlave(camera.get(), osg::Matrixd(), osg::Matrixd::rotate(osg::DegreesToRadians(180.0), 0.0, 1.0, 0.0));
// 初始化右视图
osg::ref_ptr<osg::Camera> rightViewer = new osg::Camera;
// 设置上下文
rightViewer->setGraphicsContext(gc.get());
// 设置视口位置
rightViewer->setViewport(new osg::Viewport(traits->width / 4, 0, traits->width / 4, traits->height / 4));
GLenum bufferright = traits->doubleBuffer ? GL_BACK : GL_FRONT;
rightViewer->setDrawBuffer(bufferright);
rightViewer->setReadBuffer(bufferright);
// 添加相机到视口当中
viewer.addSlave(rightViewer.get(), osg::Matrixd(), osg::Matrixd::rotate(osg::DegreesToRadians(213.0), 0.0, 1.0, 0.0));
// 初始化前视图
osg::ref_ptr<osg::Camera> frontViewer = new osg::Camera;
// 设置上下文
frontViewer->setGraphicsContext(gc.get());
frontViewer->setViewport(new osg::Viewport((traits->width / 4) * 2 - 1, 0, traits->width / 4, traits->height / 4));
GLenum bufferfront = traits->doubleBuffer ? GL_BACK : GL_FRONT;
frontViewer->setDrawBuffer(bufferfront);
frontViewer->setReadBuffer(bufferfront);
// 添加相机到视口当中
viewer.addSlave(frontViewer.get(), osg::Matrixd(), osg::Matrixd::rotate(osg::DegreesToRadians(246.0), 0.0, 1.0, 0.0));
//初始化左视图
osg::ref_ptr<osg::Camera> leftViewer = new osg::Camera;
// 上下文
leftViewer->setGraphicsContext(gc.get());
leftViewer->setViewport(new osg::Viewport((traits->width / 4) * 3 - 2, 0, traits->width / 4, traits->height / 4));
GLenum bufferleft = traits->doubleBuffer ? GL_BACK : GL_FRONT;
leftViewer->setDrawBuffer(bufferleft);
leftViewer->setReadBuffer(bufferleft);
// 添加相机到视口当中
viewer.addSlave(leftViewer.get(), osg::Matrixd(), osg::Matrixd::rotate(osg::DegreesToRadians(279.0), 0.0, 1.0, 0.0));
}
int main(int argc, char **argv) {
osgViewer::Viewer viewer;
CreateCamera(viewer);
viewer.setCameraManipulator(new osgGA::TrackballManipulator());
viewer.setSceneData(osgDB::readNodeFile("ceep.ive"));
viewer.realize();
viewer.run();
return 0;
}
书上说运行效果是图的上方是主视口，下方是主视口的后面前后左右四个面，说实在的，我没有看出来这是什么鬼，但是代码还是好理解的
2. 多窗口渲染
- 意思不大
3. LOD
-
这里有一个简单的例子来说明该功能
-
一共在场景中添加了三个球，随着鼠标滚轮的滚动，显示不同级别的数据
示例来自于返回主页 准前端工程师的博客：osg的点云lod技术预研
#include <osgViewer/Viewer>
#include <osgViewer/ViewerEventHandlers>
#include <osg/Node>
#include <osg/Geode>
#include <osg/Geometry>
#include <osgDB/ReaderWriter>
#include <osgDB/ReadFile>
#include <osgDB/WriteFile>
#include <osgGA/StateSetManipulator>
#include <osgUtil/Optimizer>
#include <osgUtil/DelaunayTriangulator>
// 创建视图所需头
#include <osgDB/Registry>
#include <osg/Node>
#include <osg/ShapeDrawable>
#include <osgGA/StateSetManipulator>
int main() {
osg::ref_ptr<osgViewer::Viewer> viewer = new osgViewer::Viewer();
// 这里还是给显示进行一下初始化来看看
{
viewer->getCamera()->setClearColor(osg::Vec4(1, 1, 0.3, 0));
osg::ref_ptr<osg::GraphicsContext::Traits> traits = new osg::GraphicsContext::Traits;
traits->x = 40;
traits->y = 40;
traits->width = 600;
traits->height = 480;
traits->windowDecoration = true;
traits->doubleBuffer = true;
traits->sharedContext = 0;
osg::ref_ptr<osg::GraphicsContext> gc = osg::GraphicsContext::createGraphicsContext(traits.get());
osg::ref_ptr<osg::Camera> camera = new osg::Camera;
camera->setGraphicsContext(gc.get());
camera->setViewport(new osg::Viewport(0, 0, traits->width, traits->height));
GLenum buffer = traits->doubleBuffer ? GL_BACK : GL_FRONT;
camera->setDrawBuffer(buffer);
camera->setReadBuffer(buffer);
// add this slave camera to the viewer, with a shift left of the projection matrix
viewer->addSlave(camera.get());
}
osg::ref_ptr<osg::Group> root = new osg::Group();
osg::ref_ptr<osg::Geode> geode = new osg::Geode();
osg::ref_ptr<osg::TessellationHints> hints = new osg::TessellationHints;
hints->setDetailRatio(0.05);// 设置精细度
geode->addDrawable(new osg::ShapeDrawable(new osg::Sphere(osg::Vec3(0.0, 0.0, 0.0), 100.0), hints.get()));
osg::ref_ptr<osg::Geode> geode2 = new osg::Geode();
osg::ref_ptr<osg::TessellationHints> hints2 = new osg::TessellationHints;
hints2->setDetailRatio(0.5);
geode2->addDrawable(new osg::ShapeDrawable(new osg::Sphere(osg::Vec3(0.0, 0.0, 0.0), 100.0), hints2.get()));
osg::ref_ptr<osg::Geode> geode3 = new osg::Geode();
osg::ref_ptr<osg::TessellationHints> hint3 = new osg::TessellationHints;
hint3->setDetailRatio(10);
geode3->addDrawable(new osg::ShapeDrawable(new osg::Sphere(osg::Vec3(0.0, 0.0, 0.0), 100.0), hint3.get()));
osg::ref_ptr<osg::LOD> lod = new osg::LOD;
lod->addChild(geode, 300, 400);
lod->addChild(geode2, 400, 600);
lod->addChild(geode3, 600, 5000);
lod->setCenter(osg::Vec3(0.0, 0.0, 0.0));
root->addChild(lod);
viewer->setSceneData(root.get());
viewer->addEventHandler(new osgGA::StateSetManipulator(viewer->getCamera()->getOrCreateStateSet()));
return viewer->run();
}
4. 多通道
- 用到时再补充吧
5. Imposter
- 用到时再补充吧