# How is the area stat calculated?

by MBraedley   Last Updated August 13, 2019 13:14 PM - source

In Opus Magnum, your solutions are graded on three factors: cost, number of cycles, and area. The first is very simple: it's the sum total for all the parts you used. The second is also straight forward: it's the number on instructions that were needed to produce the required number of molecules.

The third has me confused, though. I don't understand how the area metric is calculated. It's not simply the number of hexes occupied by your parts, nor does it seem like it's just the area ever occupied by part or element, although that does seem to be closer to the truth.

So, how exactly is the area of a solution calculated?

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Area calcuation is based on the final amount of hexes your contraption uses after being run, including arms or parts moving outside the initial area of the contraption.

Here's an example:

As you can see the area taken up by the contraption (without running it), is 7. However, once started, it moves over 2 additional hexes, making the total area count 9.

Coreus
August 13, 2019 12:49 PM

It's the number of hexes occupied, but it's often larger than you might think due to rotations (any partly-occupied hex counts).

To study the area, start your solution and press and hold the button in the group of four in the lower right, or the 2 key. This will highlight every hex that has been occupied so far with a blue outline.

Example: In these pictures, the arm 4 rotated to the left. The hex immediately to the right of the arm becomes occupied because the arm crosses it (even though this does not collide with anything) and the bottom-rightmost highlighted hex becomes occupied because the atoms passed through it (even though this was during a rotation operation, not on at the beginning or end of it).

Managing area:

• Always try to have the length of an arm stay within the otherwise-occupied area.
• You will often want to avoid rotations in favor of translations (piston and track movements) because they make molecules stick out farther than you'd like. The exception is rotations where nothing sticks out farther than 1 hex from the center of rotation — these do not occupy any extra area.
• Don't use any multi-gripper arms if those extra grippers would stick outside the working area unnecessarily.
• Your arms might not return to start in the optimal rotation direction or order of operations (rotation vs. track movement); program them manually enough steps for the instruction to take the hint.

Area-optimized solutions often contain very few arms with long programs, because every additional arm is an additional hex occupied permanently by an arm base.

Kevin Reid
August 13, 2019 12:49 PM