How to display only selected fields based on project roles in same transitions screen

[ssam]

I need to display set of custom fields based on project role and current status of an issue.

for eg,

If current state is pending approval, while transiting to next status. in pop up screen we need to display first approver comment. and if from first approval to second approval we need to display second approver comment. 

By using same screen with all required fields, need to display only fields based on role and status.