Core allows you to view the task allocation on the Gantt chart either for a project or a resource. If you wan't to view the task allocation across all active projects of an employee or a vendor, you can choose to display the Gantt chart by Resource (Employee or Vendor). For that, in Allocation and Forecasting > Task Allocation > Gantt chart, select Resource under Show and then choose the resource whose allocation you want to view. Select the other options as required. Core displays the allocations accordingly on the Gantt chart. Check the Core Help for details.