how to store the depth buffer's value into the HILO texture?

abc9804

I want to doing the operation z-zfront,zfront's values are in the depth buffer.Now I want to store these values into a HILO texture,how to do this?

I have checked the OpenGL extension specifications about the NV_texture_shader,we can build a HILO texture:

1. 
   
2. GLushort HILOtexture[] = {0, 0};
   
3. glGenTextures(1, &this->hilotextureid);
   
4. glBindTexture(GL_TEXTURE_2D, this->hilotextureid);  
   
5. glTexImage2D(GL_TEXTURE_2D, 0, GL_HILO_NV, 1, 1, 0, GL_HILO_NV,
   
6.                    GL_UNSIGNED_SHORT, &HILOtexture);
   

复制代码

these codes are from the open source,but I can't understand these,why the size of the HILO texture is 1*1? How to use it to store the depth values?should I bulid a depth texture?how to relate them?

congy

如果你是中国人，请用中文。