I figured it out! make sure on your skeletal mesh that you set the post process animation blueprint to the animation blueprint with your pose drivers in it.
Create a duplicate pose driver that is set to drive curves
- In your animation blueprint with your pose driver that is driving your skeleton. Duplicate that pose driver node.
- On the duplicated pose driver set the tag to something unique so it’s not the same as the original.
- On the duplicated pose drive set the Drive Output to Drive Curves.
- Make sure the new duplicated pose driver is in the animation pose chain by connecting the output of your input pose or anim sequence to the input of the duplicated pose driver and the output to the original pose driver.
Create a material parameter collection to drive your material
- Right click in your content browser and go Material>Material Parameter Collection.
- Name that node.
- Double click that node and add a scalar param and name it. Save it.
- In your material create a collection parameter node.
- Select that node and in the details panel choose the choose the collection node and the parameter.
- Connect the output of that node to the input of your material you want to drive.
Back in your animation blueprint with the pose drivers
- Go to the event graph in your animation blueprint
- create a set scalar parameter node and connect the execution pin to the Event Blueprint Update Animation node
- set the collection of the set scalar parameter node to the material parameter collection you made earlier
- set the parameter name to the one you created
- Create a Get Curve Value node and type in the EXACT pose name from your pose driver node that is driving curves.
- Connect the return value from the Get Curve Value node to the parameter value on the Set Scalar Parameter node.