We're using something like this:
msbuild .\DBName\DBName.sqlproj /t:build /p:Configuration="Local"
sqlpackage /a:script /tsn:TargetServer /sf:.\DBName\sql\Local\DBName.dacpac /pr:.\DBName\Publish\TargetServer.publish.xml /op:.\Scripts\DBName-TargetServer.sql
(where TargetServer and DBName make sense for your projects and the dacpac was just built) /a:Script - action == generate script /sf - dacpac for source /pr - Publish Profile to use /op - output filename
I usually combine that with the following to get a deploy report for changes:
sqlpackage /a:DeployReport /tsn:ServerName /sf:.\DBName\sql\Local\DBName.dacpac /pr:.\DBName\Publish\ServerName.publish.xml /op:.\Scripts\DBName-ServerName.xml