将俯视图渲染到纹理 Render to texture

acmiyou

//创建一个小型场景..并将俯视图渲染到纹理 保存为bmp图像文件。并使用该纹理渲染一个矩形.
//以前没学过opengl 没怎么用过.不知道texturesize需要是2^n*2^m.在设置texturesize时候 没设置正确 导致错误..
//看来要学好osg得先掌握好opengl

1. #include<osgViewer/Viewer>
   
2. #include <osgViewer/CompositeViewer>
   
3. #include<osg/Node>
   
4. #include<osg/Geode>
   
5. #include<osg/Group>
   
6. #include<osg/Geometry>
   
7. #include<osg/Matrixd>
   
8. #include<osg/Shape>
   
9. #include<osg/ShapeDrawable>
   
10. #include<osg/PositionAttitudeTransform>
    
11. #include<osgDB/WriteFile>
    
12. #include<osg/Texture2D>
    
13. #include<iostream>
    
14. struct MyCameraPostDrawCallback : public osg::Camera::DrawCallback
    
15. {
    
16.     MyCameraPostDrawCallback(osg::Image* image):
    
17.         _image(image)
    
18.     {
    
19.     }
    
20. 
    
21.     virtual void operator () (const osg::Camera& /*camera*/) const
    
22.     {
    
23.                 osgDB::writeImageFile(*_image,"skyup.bmp");
    
24.     }
    
25.     osg::Image* _image;
    
26. };
    
27. 
    
28. 
    
29. osg::ref_ptr<osg::Group> create()
    
30. {
    
31.         osg::ref_ptr<osg::Group>root=new osg::Group;
    
32.         osg::ref_ptr<osg::Geometry> geom=new osg::Geometry;
    
33. 
    
34.         osg::ref_ptr<osg::Vec3Array> v=new osg::Vec3Array;
    
35. 
    
36.         geom->setVertexArray(v.get());
    
37.         GLint count=0;
    
38.         for(float i=-100;i<=100;i++)
    
39.         {
    
40.                 count+=4;
    
41.                 v->push_back(osg::Vec3(-100.f,i,0.f));
    
42.                 v->push_back(osg::Vec3(100.f,i,0.f));
    
43.                
    
44.                 v->push_back(osg::Vec3(i,-100.f,0.f));
    
45.                 v->push_back(osg::Vec3(i,100.f,0.f));
    
46.         }
    
47.         osg::ref_ptr<osg::Vec4Array> c=new osg::Vec4Array;
    
48. 
    
49.         geom->setColorArray(c.get());
    
50.         geom->setColorBinding(osg::Geometry::BIND_OVERALL);
    
51. 
    
52.         c->push_back(osg::Vec4(0.0f,10.0f,10.0f,1.f));
    
53. 
    
54.         osg::ref_ptr<osg::Vec3Array> n= new osg::Vec3Array;
    
55. 
    
56.         geom->setNormalArray(n.get());
    
57. 
    
58.         geom->setNormalBinding(osg::Geometry::BIND_OVERALL);
    
59.         n->push_back(osg::Vec3(0.f,1.f,0.f));
    
60. 
    
61.         geom->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::LINES,0,count));
    
62.        
    
63.         osg::Geode *geode =new osg::Geode;
    
64.         geode->addDrawable(geom.get());
    
65.         root->addChild(geode);
    
66. 
    
67.         osg::Box* unitCube = new osg::Box( osg::Vec3(1,1,2), 4);
    
68. 
    
69.         osg::ShapeDrawable* unitCubeDrawable = new osg::ShapeDrawable(unitCube);
    
70. // 声明Geode类的实例
    
71.         osg::Geode* basicShapesGeode = new osg::Geode();
    
72. 
    
73. // 将单位立方体添加到Geode中
    
74.         basicShapesGeode->addDrawable(unitCubeDrawable);
    
75. 
    
76. // 将Geode添加到场景中
    
77.         root->addChild(basicShapesGeode);
    
78.         osg::Sphere* unitSphere = new osg::Sphere( osg::Vec3(1,1,2), 3);
    
79.         osg::ShapeDrawable* unitSphereDrawable = new osg::ShapeDrawable(unitSphere);
    
80.         osg::PositionAttitudeTransform* sphereXForm = new osg::PositionAttitudeTransform();
    
81.         sphereXForm->setPosition(osg::Vec3(20,-20,1.5));
    
82. 
    
83.         osg::Geode* unitSphereGeode = new osg::Geode();
    
84.         root->addChild(sphereXForm);
    
85. 
    
86.         sphereXForm->addChild(unitSphereGeode);
    
87.         unitSphereGeode->addDrawable(unitSphereDrawable);
    
88. 
    
89.         return root.get();
    
90. }
    
91. osg::Group* createHUD(osg::ref_ptr<osg::Group> root)
    
92. {
    
93. 
    
94.         osg::Group* group=new osg::Group();
    
95.         osg::Camera* camera = new osg::Camera;
    
96.         osg::Geode *geode =new osg::Geode;
    
97.         osg::Texture2D* texture2D = new osg::Texture2D;
    
98.         texture2D->setTextureSize(256,256);
    
99.         texture2D->setInternalFormat(GL_RGBA);
    
100.         texture2D->setFilter(osg::Texture2D::MIN_FILTER,osg::Texture2D::LINEAR);
     
101.         texture2D->setFilter(osg::Texture2D::MAG_FILTER,osg::Texture2D::LINEAR);
     
102.         osg::ref_ptr<osg::Geometry> geom=new osg::Geometry;
     
103.         osg::ref_ptr<osg::Vec3Array> v=new osg::Vec3Array;
     
104.         geom->setVertexArray(v.get());
     
105.         v->push_back(osg::Vec3(-100,-100,0));
     
106.         v->push_back(osg::Vec3(100,-100,0));
     
107.         v->push_back(osg::Vec3(100,100,0));
     
108.         v->push_back(osg::Vec3(-100,100,0));
     
109. 
     
110.         osg::ref_ptr<osg::Vec4Array> c=new osg::Vec4Array;
     
111.         geom->setColorArray(c.get());
     
112.         geom->setColorBinding(osg::Geometry::BIND_OVERALL);
     
113. 
     
114.         c->push_back(osg::Vec4(1.0f,1.0f,1.0f,0.5f));
     
115. 
     
116.         osg::ref_ptr<osg::Vec3Array> n= new osg::Vec3Array;
     
117. 
     
118.         geom->setNormalArray(n.get());
     
119. 
     
120.         geom->setNormalBinding(osg::Geometry::BIND_OVERALL);
     
121.         n->push_back(osg::Vec3(0.f,0.f,1.f));
     
122. 
     
123.         geom->addPrimitiveSet(new osg::DrawArrays(osg::PrimitiveSet::QUADS,0,4));
     
124. 
     
125.         osg::Vec2Array* texcoords = new osg::Vec2Array(4);
     
126.         (*texcoords)[0].set(0.0f,0.0f);
     
127.         (*texcoords)[1].set(1.0f,0.0f);
     
128.         (*texcoords)[2].set(1.0f,1.0f);
     
129.         (*texcoords)[3].set(0.0f,1.0f);
     
130.         geom->setTexCoordArray(0,texcoords);
     
131.         geom->setDataVariance(osg::Object::DYNAMIC);
     
132. 
     
133.         osg::StateSet* state = new osg::StateSet();
     
134.         state->setTextureAttributeAndModes(0,texture2D,osg::StateAttribute::ON);
     
135. 
     
136.         geom->setStateSet(state);
     
137.         geode->addDrawable(geom.get());
     
138.         group->addChild(geode);
     
139. 
     
140.     camera->setClearColor(osg::Vec4(0.1f,0.1f,0.3f,1.0f));
     
141.     camera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
     
142.         camera->setProjectionMatrix(osg::Matrix::ortho2D(-100,100,-100,100));
     
143.         camera->setReferenceFrame(osg::Transform::ABSOLUTE_RF);
     
144. 
     
145.         osg::Matrixd mat;
     
146.         osg::Vec3f _eye=osg::Vec3f(0.0,0.0,9.0);
     
147.         osg::Vec3f _center=osg::Vec3f(0.0,0.0,0.0);
     
148.         osg::Vec3f _up=osg::Vec3f(0.0,1.0,0.0);
     
149.         mat.makeLookAt(_eye,_center,_up);
     
150.         camera->setViewMatrix(mat);
     
151. 
     
152.         camera->setViewport(0,0,256,256);
     
153.         camera->setRenderOrder(osg::Camera::POST_RENDER);
     
154.         camera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);
     
155.         //camera->attach(osg::Camera::COLOR_BUFFER,texture, 0, 0, false,0,0);
     
156.         osg::Image* image=new osg::Image();
     
157.         image->allocateImage(256, 256, 1, GL_RGBA, GL_UNSIGNED_BYTE);
     
158.         camera->attach(osg::Camera::COLOR_BUFFER,image,0,0);
     
159.         texture2D->setImage(0,image);
     
160.         camera->setPostDrawCallback(new MyCameraPostDrawCallback(image));
     
161.         camera->addChild(root.get());
     
162.         group->addChild(camera);
     
163.     return group;
     
164. }
     
165. int main()
     
166. {
     
167.         osg::ref_ptr<osg::Group> root=create();
     
168.         osgViewer::Viewer viewer;
     
169.         osg::Group* ans=new osg::Group();
     
170.         ans->addChild(createHUD(root));
     
171.         viewer.setSceneData(ans);
     
172.         viewer.run();
     
173. }

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[ 本帖最后由 acmiyou 于 2009-6-6 01:58 编辑 ]

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