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15 February 2007 91,014 views 3 Comments

Required render passes

Post Light only requires 5 passes from your scene:

  • Color pass
  • Specular pass
  • Roughness pass
  • Normal pass
  • Position pass

Once you have rendered these, Post Light has almost all the information it needs to be able to light your scene correctly. The only other bit of information Post Light needs, is the camera position, which is read directly from the scene. This is needed to be able to render the specular lighting correctly.

The "PostLightPhong" shader

To make things easier for you, I’ve put together a special modified phong shader called PostLightPhong that will output the different passes for you.

It contains a single parameter that lets you switch the output of the shader between each pass, making it incredibly easy to set up in your passes. It’ also guaranteed to render identically to the standard XSI phong shader, since it actually contains the XSI phong shader in it’s implementation.

To add the PostLightPhong shader to your render tree, you need to add it through the render tree’s Node menu. Select the Illumination->More… menu option and use the Paths drop down menu on the right hand side of the file browser to navigate to the Post Light addon menu. From here you can select the PostLightPhong preset.

The PostLightPhong shader is identical to XSI’s standard Phong shader, so you can replace any existing Phong shaders without worrying that the render will be different. The only difference is an extra parameter called “Post Light Pass” on the first tab of the interface. This parameter allows you to get the Post Light Phong shader to output each of the five passes needed for Post Light.

With the Post Light Pass parameter set to “Phong Shader”, it will render identically to XSI’s standard Phong shader. Each of the other settings corresponds to one of the passes required by the Post Light FXTree plugin. This means that when you are setting up your render passes, you only need to add one override for this parameter for each pass. This makes setting up the render passes much easier than having to construct the passes manually.

The PostLightPhong shader takes all the hard work out of producing the render passes. The only thing you need to remember is to use the correct output format for each pass.

Color Standard with alpha (e.g. 32 bit Targa)
Specular Standard (e.g. Targa)
Specular Shininess Floating point (e.g. Floating point TIFF)
Normal Standard (e.g. Targa)
Position Floating point (e.g. Floating point TIFF)

Please note:

Enabling bump on an input shader that is plugged into the PostLightPhong shader, will not work when generating the Normal pass. All bump shaders must go into the bump input of the PostLightPhong shader, or into the material bump input.

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  • Adam Seeley said:

    Hi, Any idea if this works in Xp 64 bit Soft 2010/2011/2011 sp1.



  • AndyN (author) said:

    Hi Adam,
    That’s a good question. I can’t see a reason why not, but it would need to be recompiled and I’m afraid I don’t have access to a Windows 64bit machine.

    It could only support phong based lighting models so it didn’t catch on as it probably wasn’t flexible enough for most pipelines. Anyway, as a result, I haven’t kept it up to date.


  • Moykul said:

    Brilliant tool! Thank you so much!

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