Hey Ross,
Sure, we gladly answer them for you!
1- In the Sprite Template -- what does the offset input do? I've messed around with it for awhile and noticed its use in one of the examples but I'm still having trouble wrapping my head around it.You just found a bug, the Offset input should allow you to apply an offset to your vertex position.
Thanks to you, we found an issue where the value set on that input port is being ignored in some cases thus causing confusion on your end. We apologize for this.
2 - In the "Simple Sprite" example -- where is _AlphaTex defined? I see that it's global and that there is an affect when I remove it from the graph -- but I can't find where it's actually set.This value is being set on the Sprite Templates. When you create a shader based on a Template it inherits all its shader properties and global variables.
You can at any point see the contents of the template your're using by hitting the Edit Template button on the Ouput Node Properties window.
You can access these inherited parameters from your shader by using the Templates Parameter node.
3 - What's the use of the swizzle node when the append node's functionality seems to encompass the swizzle's functionality plus more? I noticed that the swizzle node is used a lot in the examples -- so presumably it has some advantage, performance-wise maybe?Swizzle and Append are very different nodes. An Append node allows the creation of a new vector from different sources as the Swizzle node does a swizzle operation which allows you to reorganize or access certain channels of a vector.
So bottom-line, if you just need to access to certain channels of a single vector than you should use Swizzle, if you need to create a new vector from different sources then you should use Append.
Please check the following link for more information on the Append node:
http://wiki.amplify.pt/index.php?title=Unity_Products:Amplify_Shader_Editor/AppendPlease check the following link for more information on the Swizzle node:
http://wiki.amplify.pt/index.php?title=Unity_Products:Amplify_Shader_Editor/SwizzleRegarding the Offset issue, rest assured that it will be fixed on our next build. We'll let you know as soon as it is available.
Please let us know if you have further questions!