【多重采样纹理】【后处理】使用Texture2DMultisample作为FBO输出的后处理例子

smtKafka

国内外论坛搜了一下没有相关的例子，尝试写了一个记录一下。重点说明：颜色和深度纹理都要写，且OSG_GL_TEXTURE_STORAGE设置一致。

1. #include <osg/Group>
   
2. #include <osg/Geode>
   
3. #include <osg/Geometry>
   
4. #include <osg/Camera>
   
5. #include <osgViewer/Viewer>
   
6. #include <osgGA/StateSetManipulator>
   
7. #include <osg/Texture2D>
   
8. #include <osg/Texture2DMultisample>
   
9. #include <Windows.h>
   
10. 
    
11. int main()
    
12. {
    
13.     putenv("OSG_GL_TEXTURE_STORAGE=DISABLE");
    
14. 
    
15.     const double w = 800;
    
16.     const double h = 600;
    
17.     // 创建场景图
    
18.     osg::ref_ptr<osg::Group> root = new osg::Group;
    
19. 
    
20.     // 创建采样相机
    
21.     osg::ref_ptr<osg::Camera> renderToTextureCamera = new osg::Camera;
    
22.     renderToTextureCamera->setRenderOrder(osg::Camera::PRE_RENDER);
    
23. 
    
24.     renderToTextureCamera->setClearMask(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    
25.     renderToTextureCamera->setClearColor(osg::Vec4(0.0, 0.0, 0.0, 0.0));
    
26.     renderToTextureCamera->setViewport(0, 0, w, h);
    
27. 
    
28.     osg::ref_ptr<osg::Geode> geode = new osg::Geode;
    
29.     // 创建红色矩形的顶点数组
    
30.     osg::ref_ptr<osg::Vec3Array> vertices = new osg::Vec3Array;
    
31.     //vertices->push_back(osg::Vec3(-0.5, -0.5, 0.0));
    
32.     //vertices->push_back(osg::Vec3(0.5, -0.5, 0.0));
    
33.     //vertices->push_back(osg::Vec3(0.5, 0.5, 0.0));
    
34.     //vertices->push_back(osg::Vec3(-0.5, 0.5, 0.0));
    
35. 
    
36.     vertices->push_back(osg::Vec3(-0.5, 0.0, -0.5));
    
37.     vertices->push_back(osg::Vec3(0.5, 0.0, -0.5));
    
38.     vertices->push_back(osg::Vec3(0.5, 0.0, 0.5));
    
39.     vertices->push_back(osg::Vec3(-0.5, 0.0, 0.5));
    
40.     // 创建红色矩形的颜色数组
    
41.     osg::ref_ptr<osg::Vec4Array> colors = new osg::Vec4Array;
    
42.     colors->push_back(osg::Vec4(1.0, 0.0, 0.0, 1.0)); // 红色
    
43. 
    
44.     // 创建Geometry并设置顶点和颜色数组
    
45.     osg::ref_ptr<osg::Geometry> geometry = new osg::Geometry;
    
46.     geometry->setVertexArray(vertices);
    
47.     geometry->setColorArray(colors, osg::Array::BIND_OVERALL);
    
48.     geometry->addPrimitiveSet(new osg::DrawArrays(GL_QUADS, 0, 4));
    
49.     geode->addDrawable(geometry);
    
50. 
    
51.     // 添加红色球到采样相机
    
52.     renderToTextureCamera->addChild(geode);
    
53.     root->addChild(renderToTextureCamera);
    
54. 
    
55.     // 创建一个纹理用于存储渲染结果
    
56.     osg::ref_ptr<osg::Texture2D> textureColor = new osg::Texture2D;
    
57.     textureColor->setTextureSize(512, 512);
    
58.     textureColor->setInternalFormat(GL_RGBA);
    
59. 
    
60.     osg::ref_ptr<osg::Texture2D> textureDepth = new osg::Texture2D;
    
61.     textureDepth->setTextureSize(512, 512);
    
62.     textureDepth->setInternalFormat(GL_DEPTH_COMPONENT24);
    
63. 
    
64.     osg::ref_ptr<osg::Texture2DMultisample> textureMSColor = new osg::Texture2DMultisample(4, true);
    
65.     textureMSColor->setTextureSize(512, 512);
    
66.     textureMSColor->setInternalFormat(GL_RGBA);
    
67. 
    
68.     osg::ref_ptr<osg::Texture2DMultisample> textureMSDepth = new osg::Texture2DMultisample(4, true);
    
69.     textureMSDepth->setTextureSize(512, 512);
    
70.     textureMSDepth->setInternalFormat(GL_DEPTH_COMPONENT24);
    
71. 
    
72.     // 设置渲染到纹理的相机的纹理
    
73.     renderToTextureCamera->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);
    
74.     renderToTextureCamera->setRenderOrder(osg::Camera::POST_RENDER);
    
75. 
    
76.     bool isMultisample = true;
    
77. 
    
78.     if (isMultisample)
    
79.     {
    
80.         renderToTextureCamera->attach(osg::Camera::COLOR_BUFFER, textureMSColor);
    
81.         renderToTextureCamera->attach(osg::Camera::DEPTH_BUFFER, textureMSDepth);
    
82.     }
    
83.     else
    
84.     {
    
85.         renderToTextureCamera->attach(osg::Camera::COLOR_BUFFER, textureColor);
    
86.         //renderToTextureCamera->attach(osg::Camera::DEPTH_BUFFER, textureDepth);
    
87.     }
    
88. 
    
89.     // 创建HUD相机
    
90.     osg::ref_ptr<osg::Camera> hudCamera = new osg::Camera;
    
91.     hudCamera->setClearMask(GL_DEPTH_BUFFER_BIT);
    
92.     hudCamera->setReferenceFrame(osg::Camera::ABSOLUTE_RF);
    
93.     hudCamera->setViewMatrix(osg::Matrix::identity());
    
94.     hudCamera->setProjectionMatrix(osg::Matrix::ortho2D(0, w, 0, h));
    
95.     hudCamera->setRenderOrder(osg::Camera::POST_RENDER);
    
96. 
    
97.     hudCamera->setViewport(0, 0, w, h);
    
98.     hudCamera->setAllowEventFocus(false);
    
99.     hudCamera->setCullingActive(false);
    
100. 
     
101.     // 创建顶点着色器
     
102.     osg::ref_ptr<osg::Shader> vertShader = new osg::Shader(osg::Shader::VERTEX, R"(
     
103.     #version 430
     
104.     layout(location = 0) in vec3 VertexPosition;
     
105.     out vec2 TexCoord;
     
106.     void main()
     
107.     {
     
108.         TexCoord = (VertexPosition.xy + vec2(1.0)) * 0.5; // 转换到纹理坐标范围 [0, 1]
     
109.         gl_Position = vec4(VertexPosition, 1);
     
110.     }
     
111.     )");
     
112. 
     
113.     // 创建带有多重采样支持的片段着色器
     
114.     osg::ref_ptr<osg::Shader> fragShaderMS = new osg::Shader(osg::Shader::FRAGMENT, R"(
     
115.     #version 430
     
116.     #extension GL_ARB_texture_multisample : enable
     
117. 
     
118.     in vec2 TexCoord;
     
119.     out vec4 FragColor;
     
120.     uniform sampler2DMS tex; // 多重采样纹理
     
121. 
     
122.     void main()
     
123.     {
     
124.         ivec2 texSize = textureSize(tex);
     
125.         ivec2 coord = ivec2(TexCoord * vec2(texSize));
     
126.         vec4 a1 = texelFetch(tex, coord, 0);
     
127.         vec4 a2 = texelFetch(tex, coord, 1);
     
128.         vec4 a3 = texelFetch(tex, coord, 2);
     
129.         vec4 a4 = texelFetch(tex, coord, 3);
     
130.         //FragColor = (a1+a2+a3+a4)/4.0;
     
131.         FragColor = a1;
     
132.     }
     
133.     )");
     
134. 
     
135.     // 创建不带多重采样的片段着色器
     
136.     osg::ref_ptr<osg::Shader> fragShader = new osg::Shader(osg::Shader::FRAGMENT, R"(
     
137.     #version 430
     
138.     in vec2 TexCoord;
     
139.     out vec4 FragColor;
     
140.     uniform sampler2D tex;
     
141. 
     
142.     void main()
     
143.     {
     
144.         FragColor = texture(tex, TexCoord);
     
145.     }
     
146.     )");
     
147. 
     
148.     // 创建Program，并将Shader附加到其中
     
149.     osg::ref_ptr<osg::Program> program = new osg::Program;
     
150.     program->addShader(vertShader);
     
151.     if (isMultisample)
     
152.     {
     
153.         program->addShader(fragShaderMS);
     
154.     }
     
155.     else
     
156.     {
     
157.         program->addShader(fragShader);
     
158.     }
     
159. 
     
160.     // 将Program设置到hudGeometry的StateSet中
     
161.     hudCamera->getOrCreateStateSet()->setAttributeAndModes(program, osg::StateAttribute::ON);
     
162. 
     
163.     // 创建HUD相机中显示纹理的节点
     
164.     osg::ref_ptr<osg::Geode> hudGeode = new osg::Geode;
     
165.     osg::ref_ptr<osg::Geometry> hudGeometry = osg::createTexturedQuadGeometry(osg::Vec3(-1.0f, -1.0f, 0.0f), osg::Vec3(2.0f, 0.0f, 0.0f), osg::Vec3(0.0f, 2.0f, 0.0f));
     
166.     hudGeode->addDrawable(hudGeometry);
     
167. 
     
168.     // 设置HUD相机的纹理
     
169.     if (isMultisample)
     
170.     {
     
171.         hudCamera->getOrCreateStateSet()->setTextureAttributeAndModes(0, textureMSColor, osg::StateAttribute::ON);
     
172.     }
     
173.     else
     
174.     {
     
175.         hudCamera->getOrCreateStateSet()->setTextureAttributeAndModes(0, textureColor, osg::StateAttribute::ON);
     
176.     }
     
177.     hudCamera->getOrCreateStateSet()->addUniform(new osg::Uniform("tex", 0));
     
178.     hudGeometry->getOrCreateStateSet()->setMode(GL_LIGHTING, osg::StateAttribute::OFF);
     
179. 
     
180.     hudCamera->addChild(hudGeode);
     
181.     root->addChild(hudCamera);
     
182. 
     
183.     // 创建查看器
     
184.     osgViewer::Viewer viewer;
     
185.     viewer.setSceneData(root);
     
186. 
     
187.     // 添加事件处理器
     
188.     viewer.addEventHandler(new osgGA::StateSetManipulator(viewer.getCamera()->getOrCreateStateSet()));
     
189.     viewer.setUpViewInWindow(100, 100, w, h);
     
190. 
     
191.     viewer.run();
     
192. }
     

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