Does Fast Volume Rendering have the third way?

Now I know that there are two way for Fast Volume Rendering.The first is to use glColorTableExt.And the second is to use shading language.Does Fast Volume Rendering have the third way?Like Texture Combiner?
this is the code I found in some place:

    //--------------------------------------------------
			// Initialization Step 1: Texture Setup
			//--------------------------------------------------
			// first texture stage
			glActiveTextureARB(GL_TEXTURE0_ARB);
			// disable 2D textures, enable 3D texture	
			glDisable(GL_TEXTURE_2D);
			glEnable(GL_TEXTURE_3D_EXT);
			// enable the texture shader
			glEnable(GL_TEXTURE_SHADER_NV);
            glTexEnvi(GL_TEXTURE_SHADER_NV, GL_SHADER_OPERATION_NV, GL_TEXTURE_3D);
			
			// second texture stage = dependent texture (Alpha and Red component)
			glActiveTextureARB(GL_TEXTURE1_ARB);
			// disable 2D textures, enable 3D texture
			glEnable(GL_TEXTURE_2D);
			// enable the texture shader
			glEnable(GL_TEXTURE_SHADER_NV);
			// bind the texture that contains the color table
			glBindTexture(GL_TEXTURE_2D, m_pDependentTexNames[0]); 
			// enable linear interpolation
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);  
			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);  
			// setup for dependent texture lookup 
			glTexEnvi(GL_TEXTURE_SHADER_NV, GL_SHADER_OPERATION_NV, GL_DEPENDENT_AR_TEXTURE_2D_NV );
			glTexEnvi(GL_TEXTURE_SHADER_NV, GL_PREVIOUS_TEXTURE_INPUT_NV, GL_TEXTURE0_ARB);

Does it use the Texture Combiner to deal with the Data Texture and the Lookup table Texture?

These code come from OpenQvis.I Search all the sources,but did not find shading language.And my graphic card does not support glColorTableEXT.So I want to know whether there is another way for Fast Volume Rendering.

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