Sum of 3 fields depending on user login??

Sum of 3 fields depending on user login??

Would love for someone to help me out with this. I can't think of a solution and have spent SO many hours....

I am using a form, where up to 3 users can split a commission on a team. The main agent adds the file, then they add one or two agents to share commission. Then, 3 fields are calculated that shows the commission for agent 1, agent 2 and agent 3. 

Now, I want each agent to be able to see their commission in a view or report form. I would prefer it to show as one field only, that represents the amount they earned, regardless if they were agent 1, 2 or 3 in the form fields. 

So, to give an example (this is not real code!)

IF Agent_1 == zoho.loginuserid then Agent_1_Commission, else 0
ADD (+)
IF Agent_2 == zoho.loginuserid then Agent_2_Commission, else 0
ADD (+)
IF Agent_3 == zoho.loginuserid then Agent_3_Commission, else 0
EQUALS = Total commission to logged in agent

I know the above is not real code, but might help explain what I am trying to do. I cannot find a place to filter like this. Not in formula fields, for view criteria. Not in report aggregate formula. I just don't know how I can make this into one field depending on user login.  Please help!!! So greatly appreciated!!