重用颜色传递函数和透明度传递函数

    // MIP
    // Create an opacity ramp from the window and level values.
    // Color is white. Blending is MIP.
    case 0:
      colorFun->AddRGBSegment(0.0, 1.0, 1.0, 1.0, 255.0, 1.0, 1.0, 1.0 );
      opacityFun->AddSegment( opacityLevel - 0.5*opacityWindow, 0.0,
                              opacityLevel + 0.5*opacityWindow, 1.0 );
      mapper->SetBlendModeToMaximumIntensity();
      break;

    // CompositeRamp
    // Create a ramp from the window and level values. Use compositing
    // without shading. Color is a ramp from black to white.
    case 1:
      colorFun->AddRGBSegment(opacityLevel - 0.5*opacityWindow, 0.0, 0.0, 0.0,
                              opacityLevel + 0.5*opacityWindow, 1.0, 1.0, 1.0 );
      opacityFun->AddSegment( opacityLevel - 0.5*opacityWindow, 0.0,
                              opacityLevel + 0.5*opacityWindow, 1.0 );
      mapper->SetBlendModeToComposite();
      property->ShadeOff();
      break;

    // CompositeShadeRamp
    // Create a ramp from the window and level values. Use compositing
    // with shading. Color is white.
    case 2:
      colorFun->AddRGBSegment(0.0, 1.0, 1.0, 1.0, 255.0, 1.0, 1.0, 1.0 );
      opacityFun->AddSegment( opacityLevel - 0.5*opacityWindow, 0.0,
                              opacityLevel + 0.5*opacityWindow, 1.0 );
      mapper->SetBlendModeToComposite();
      property->ShadeOn();
      break;

    // CT_Skin
    // Use compositing and functions set to highlight skin in CT data
    // Not for use on RGB data
    case 3:
      colorFun->AddRGBPoint( -3024, 0, 0, 0, 0.5, 0.0 );
      colorFun->AddRGBPoint( -1000, .62, .36, .18, 0.5, 0.0 );
      colorFun->AddRGBPoint( -500, .88, .60, .29, 0.33, 0.45 );
      colorFun->AddRGBPoint( 3071, .83, .66, 1, 0.5, 0.0 );

      opacityFun->AddPoint(-3024, 0, 0.5, 0.0 );
      opacityFun->AddPoint(-1000, 0, 0.5, 0.0 );
      opacityFun->AddPoint(-500, 1.0, 0.33, 0.45 );
      opacityFun->AddPoint(3071, 1.0, 0.5, 0.0);

      mapper->SetBlendModeToComposite();
      property->ShadeOn();
      property->SetAmbient(0.1);
      property->SetDiffuse(0.9);
      property->SetSpecular(0.2);
      property->SetSpecularPower(10.0);
      property->SetScalarOpacityUnitDistance(0.8919);
      break;

    // CT_Bone
    // Use compositing and functions set to highlight bone in CT data
    // Not for use on RGB data
    case 4:
      colorFun->AddRGBPoint( -3024, 0, 0, 0, 0.5, 0.0 );
      colorFun->AddRGBPoint( -16, 0.73, 0.25, 0.30, 0.49, .61 );
      colorFun->AddRGBPoint( 641, .90, .82, .56, .5, 0.0 );
      colorFun->AddRGBPoint( 3071, 1, 1, 1, .5, 0.0 );

      opacityFun->AddPoint(-3024, 0, 0.5, 0.0 );
      opacityFun->AddPoint(-16, 0, .49, .61 );
      opacityFun->AddPoint(641, .72, .5, 0.0 );
      opacityFun->AddPoint(3071, .71, 0.5, 0.0);

      mapper->SetBlendModeToComposite();
      property->ShadeOn();
      property->SetAmbient(0.1);
      property->SetDiffuse(0.9);
      property->SetSpecular(0.2);
      property->SetSpecularPower(10.0);
      property->SetScalarOpacityUnitDistance(0.8919);
      break;

    // CT_Muscle
    // Use compositing and functions set to highlight muscle in CT data
    // Not for use on RGB data
    case 5:
      colorFun->AddRGBPoint( -3024, 0, 0, 0, 0.5, 0.0 );
      colorFun->AddRGBPoint( -155, .55, .25, .15, 0.5, .92 );
      colorFun->AddRGBPoint( 217, .88, .60, .29, 0.33, 0.45 );
      colorFun->AddRGBPoint( 420, 1, .94, .95, 0.5, 0.0 );
      colorFun->AddRGBPoint( 3071, .83, .66, 1, 0.5, 0.0 );

      opacityFun->AddPoint(-3024, 0, 0.5, 0.0 );
      opacityFun->AddPoint(-155, 0, 0.5, 0.92 );
      opacityFun->AddPoint(217, .68, 0.33, 0.45 );
      opacityFun->AddPoint(420,.83, 0.5, 0.0);
      opacityFun->AddPoint(3071, .80, 0.5, 0.0);

      mapper->SetBlendModeToComposite();
      property->ShadeOn();
      property->SetAmbient(0.1);
      property->SetDiffuse(0.9);
      property->SetSpecular(0.2);
      property->SetSpecularPower(10.0);
      property->SetScalarOpacityUnitDistance(0.8919);
      break;

    // RGB_Composite
    // Use compositing and functions set to highlight red/green/blue regions
    // in RGB data. Not for use on single component data
    case 6:
      opacityFun->AddPoint(0, 0.0);
      opacityFun->AddPoint(5.0, 0.0);
      opacityFun->AddPoint(30.0, 0.05);
      opacityFun->AddPoint(31.0, 0.0);
      opacityFun->AddPoint(90.0, 0.0);
      opacityFun->AddPoint(100.0, 0.3);
      opacityFun->AddPoint(110.0, 0.0);
      opacityFun->AddPoint(190.0, 0.0);
      opacityFun->AddPoint(200.0, 0.4);
      opacityFun->AddPoint(210.0, 0.0);
      opacityFun->AddPoint(245.0, 0.0);
      opacityFun->AddPoint(255.0, 0.5);

      mapper->SetBlendModeToComposite();
      property->ShadeOff();
      property->SetScalarOpacityUnitDistance(1.0);
      break;

demo：https://lorensen.github.io/VTKExamples/site/Cxx/VolumeRendering/FixedPointVolumeRayCastMapperCT/