Shaders

UGUIDOTS provides specialized materials and that are compatible to URP to handle Translation and FillAmount.

Default UI Material

The Default UI Material works with Universal Render Pipeline, but has limitations in that the transformation matrix has to be updated in the mesh exclusively.

If a UI element has to move, instead of exclusively just updating the transformation matrix, we can copy the translation to the shader instead.

Material Property Index

All images and text elements have a MaterialPropertyIndex component which allows the element to access the index of the MaterialPropertyBatch in the root canvas.

By accessing the index, you are able to retrieve the associated material property and manipulate any properties.

DefaultImage Material

The DefaultImage material is very similar to the DefaultUI material, except that it allows for translation and fill.

The UIPingPongSystem and HeartFillSystem in the UGUIDots.Samples provides an example of updating the translation and fill property.

• For translation, simply pass a Vector4 to the Translation property. The translation is added in the Vertex pass in local space and the matrix is converted in world space when rendering.
• For fill, ensure that the shader supports fill amount and pass a float to the FillAmount property.

All properties that are supported can be found in the ShaderConstants static class.

Limitations

Canvas Rebuilds

• If you have a continuously moving element in your UI and you schedule a Canvas rebuild - original transformation is not properly resetted. This creates a very odd offset effect.

Batching

Each material property is associated with a collection of elements.

Imagine a canvas with 3 batches. There is only 1 material property per batch, as a batch is a collective representation of the same properties.

• Canvas
  • A -> Material Property A
  • B -> Material Property B
  • C -> Material Property C

If you need to update UI Elements individually that are in the same batch, currently, the only recommended way is to separate the elements from the batch. Currently the HeartFillSystem does this if you inspect the # of batches in the Fill Canvas in the sample.

I understand that this is a cumbersome workflow. I will likely introduce a much more comprehensive analysis window in the future to handle this situation better.