render to Texture3D

huidian200803

最近学习一下渲染到3D纹理，创建一个256*256深度为32的3D纹理如下

1.                 osg::Texture3D* _texture = new osg::Texture3D;
   
2.                 _texture->setTextureSize(256,256,32);
   
3.                 _texture->setFilter(osg::Texture::MIN_FILTER,osg::Texture::LINEAR);
   
4.                 _texture->setFilter(osg::Texture::MAG_FILTER,osg::Texture::LINEAR);
   
5.                 _texture->setWrap(osg::Texture::WRAP_S,osg::Texture::CLAMP_TO_EDGE);
   
6.                 _texture->setWrap(osg::Texture::WRAP_T,osg::Texture::CLAMP_TO_EDGE);
   
7.                 _texture->setWrap(osg::Texture::WRAP_R,osg::Texture::CLAMP_TO_EDGE);
   
8.                 _texture->setInternalFormat(GL_RGB16F_ARB);
   
9.                 _texture->setSourceFormat (GL_RGB);
   
10.                 _texture->setSourceType(GL_FLOAT);
    
11.                

复制代码

创建一个平面pannel_1节点，一个2D的rtt相机cameraRtt，

场景根节点下面添加cameraRtt，cameraRtt下面添加pannel_1，cameraRtt始终(0,0,1)看(0,0,0)方向(0,1,0),pannel_1添加shader，使用geometry shader

1. shader = osg::Shader::readShaderFile(osg::Shader::GEOMETRY,filePath);
   
2.         pro->addShader(shader);       
   
3.         pro->setParameter( GL_GEOMETRY_VERTICES_OUT_EXT, 3 );
   
4.         pro->setParameter( GL_GEOMETRY_INPUT_TYPE_EXT, GL_TRIANGLES );
   
5.         pro->setParameter( GL_GEOMETRY_OUTPUT_TYPE_EXT, GL_TRIANGLE_STRIP );

复制代码

cameraRtt渲染到纹理，

1. 
   
2. m_cameraRtt->attach(osg::Camera::COLOR_BUFFER0,m_RttTexture3D.get(),0,m_cameraRtt->FACE_CONTROLLED_BY_GEOMETRY_SHADER);
   
3. m_cameraRtt->setRenderTargetImplementation(osg::Camera::FRAME_BUFFER_OBJECT);

复制代码

在shader中传入layer对层更新，

1.                        
   
2. osg::StateSet *state =  pannel_1->getOrCreateStateSet();
   
3. #if 1
   
4.                         {
   
5.                                 state->getOrCreateUniform("layer",osg::Uniform::INT)->set( m_layer);
   
6.                                 ++m_layer;
   
7.                                 if (m_layer==32)
   
8.                                 {
   
9.                                         m_layer = 0;
   
10.                                 }
    
11.                         }
    
12. #else
    
13.                         for (int layer = 0; layer < 32; ++layer)
    
14.                         {
    
15.                                 state->getOrCreateUniform("layer",osg::Uniform::INT)->set( m_layer);
    
16.                         }
    
17. #endif

复制代码

这里我也不太清楚是一更新设置一下layer还是一次更新设置多次设置layer的值，
vertex shader如下：

1. void main()
   
2. {
   
3.         gl_Position = ftransform();
   
4.         gl_TexCoord[0] = gl_MultiTexCoord0;
   
5.         gl_FrontColor = gl_Color;
   
6. }
   

复制代码

frag shader如下：

1. uniform sampler2D uTexture2D0;
   
2. void main()
   
3. {
   
4.         vec4   color  = texture2D(uTexture2D0,gl_TexCoord[0]);
   
5.         gl_FragData[0] = color;
   
6. }
   
7. 
   

复制代码

geometry   shader如下：

1. #version 120
   
2. uniform int layer;
   
3. #extension GL_EXT_geometry_shader4 : enable
   
4. void main()
   
5. {
   
6.         for(int i =0  ; i < gl_VerticesIn ; ++i)
   
7.         {
   
8.                 gl_Position = gl_PositionIn[i];
   
9.                  gl_TexCoord[0] = gl_TexCoordIn[i][0];
   
10.                 gl_Layer = layer;
    
11.                 EmitVertex();
    
12.         }
    
13.         EndPrimitive();
    
14. }
    

复制代码

在主相机下面添加一个面板pannel_2 设置纹理为 Texture3D，使用shader传入layer 通过gl_TexCoord[0].z = (layer)/32.0 来获取纹理，最后发现只有pannel_2的layer=0.0时才有纹理。
想要实现rtt 到Texture3D，通过geometry shader的gl_Layer改变图层，然后在贴到平面上显示，结果并未如愿，不知道哪里有问题，谁会这个帮忙指导一下啊！

看了一下osg源码，源码中camera里貌似是一下过程

1. void Camera::attach(BufferComponent buffer, osg::Texture* texture, unsigned int level, unsigned int face, bool mipMapGeneration,
   
2.                     unsigned int multisampleSamples,
   
3.                     unsigned int multisampleColorSamples)
   
4. {
   
5.     _bufferAttachmentMap[buffer]._texture = texture;
   
6.     _bufferAttachmentMap[buffer]._level = level;
   
7.     _bufferAttachmentMap[buffer]._face = face;
   
8.     _bufferAttachmentMap[buffer]._mipMapGeneration = mipMapGeneration;
   
9.     _bufferAttachmentMap[buffer]._multisampleSamples = multisampleSamples;
   
10.     _bufferAttachmentMap[buffer]._multisampleColorSamples = multisampleColorSamples;
    
11. }

复制代码

把attach对象存入map中，而后在FrameBufferObject中

1. FrameBufferAttachment::FrameBufferAttachment(Camera::Attachment& attachment)
   
2. {
   
3. ........
   
4. osg::Texture3D* texture3D = dynamic_cast<osg::Texture3D*>(texture);
   
5.         if (texture3D)
   
6.         {
   
7.             _ximpl = new Pimpl(Pimpl::TEXTURE3D, attachment._level);
   
8.             _ximpl->textureTarget = texture3D;
   
9.             _ximpl->zoffset = attachment._face;
   
10.             return;
    
11.         }
    
12. .............
    
13. }

复制代码

1. FrameBufferAttachment::FrameBufferAttachment(Texture3D* target, unsigned int zoffset, unsigned int level)
   
2. {
   
3.     _ximpl = new Pimpl(Pimpl::TEXTURE3D, level);
   
4.     _ximpl->textureTarget = target;
   
5.     _ximpl->zoffset = zoffset;
   
6. }

复制代码

1. void FrameBufferAttachment::attach(State &state, GLenum target, GLenum attachment_point, const FBOExtensions* ext) const
   
2. {
   
3. ........
   
4.   case Pimpl::TEXTURE3D:
   
5.         if (_ximpl->zoffset == Camera::FACE_CONTROLLED_BY_GEOMETRY_SHADER)
   
6.         {
   
7.             if (ext->glFramebufferTexture)
   
8.             {
   
9.                 ext->glFramebufferTexture(target, attachment_point, tobj->id(), _ximpl->level);
   
10.             }
    
11.         }
    
12.         else
    
13.             ext->glFramebufferTexture3D(target, attachment_point, GL_TEXTURE_3D, tobj->id(), _ximpl->level, _ximpl->zoffset);
    
14.         break;
    
15. ........
    
16. }

复制代码

我设置attach应该也没错啊，使用了Camera::FACE_CONTROLLED_BY_GEOMETRY_SHADER，求大神指导并纠正错误·····