While you are shown visually which objects you can or can't place and how big of a chunk of your resources an object will cost, you can't precisely plan placing of objects based on the visual info from the bar alone.
I suggest adding a numeric representation of "current/max resources" in the Zeus point bar.
The amount of resources you will spend on an object could also be placed in the resource bar in a format such as "current/max (-cost)" when an object is selected in the tree.
The resources are intentionally abstract, visualized by a progress bar rather than by numbers. It allows greater flexibility, as many costs are currently numbers like 0.015625, which wouldn't look very appealing on the screen.
When you look at other games, numerical value is usually used when it represents some specific resources, e.g., money, mana, wood, coal, ... However, the resources in Zeus aren't specific, so it wouldn't make sense to show some numbers. This was design intention from the beginning.
Just because they do not have an even more specific name, it does not mean they do not behave like other types. They're all resources. Money is still money and behaves like money when you spend it even if you don't call it Euro. They can be called Zeus' farts, they still behave like vespene gas. :)
The problem comes from the fact that you might have 0.9998 resources remaining, and a unit costs 0.3333. Let's say you've already placed a very expensive vehicle that needs 3 crew members and you want to man it with 3 generic rifleman.
When you look at the bar, it seems like you can place three units.
After placing 2 units down, you suddenly cannot place the third because you do not have enough resources, even if to the user, the portion of the bar is visually the same size as it was needed for the ones that you placed down already.
Additional problem comes when you are low on resources to the point where you cannot place anything but you still have some resources. Selecting a rifleman, the airplane or a flare, colors the bar red completely and you have no idea what the relative difference between the cost of the three is.
The problem becomes incredibly annoying when you are a Zeus with limited resources that do not regenerate over short amounts of time, but instead you don't get them back at all or you get them at the end of a round (ZvP Defend Kamino). And it intensifies even more, when deleting objects you placed does not give you the resources you spent on it back (ZvP Defend Kamino again).
To me, the obvious solution were numbers, even if in the data they are represented as floats, you can still move that decimal point and convert them to ints with multiplication. 0.015625 can be still represented as 15625 in the UI.
If you do not think numbers are a viable, simple solution to the problems in the ticket and this comment, I ask of you to come up with solution which removes the above mentioned frustrations while playing a resource limited Zeus because your ability to plan ahead is limited.
Thanks for the problem explanation, it's very helpful.
I imagine that instead of showing cost preview of just one unit, we could should multiple previews in a row to see how many times you can build the unit with current resources.
That could certainly work!
The potential solution to the second issue, relative costs when the bar is empty to the point where you cannot place even a single unit, could be that 2 segments of the bar appear. The red part that colors your remaining resources as it is now and another one, to its right, colored differently that shows how large portion of the bar you need for the unit.
To illustrate:
http://i.imgur.com/MjGQ2ds.png