Why not make everything lit?

There are costs to every feature we put in X-Plane…the obvious ones include:

• The time to code the feature.
• The time to test the feature.
• The time to recode the feature if we ever rewrite the rendering engine (which we do fairly often to try to take advantage of the latest graphics technology).

There are also some less obvious costs:

• If a feature isn’t used often, it’s more likely to end up broken without anyone noticing, reducing the overall quality of X-Plane.
• We have to keep track of our use of graphics card resources. If we add a feature (like lighting) now, perhaps this will prevent us from reliably putting a new more improtant feature in later because some scenery may be using all of the card’s resources.

For example, what if we discover that we can make crashing waves, but only on unlit beaches? If we never added lit beaches, we know this is safe. But if we do support it beaches, then perhaps there is some scenery out there for which the crashing waves won’t work because we can’t have both.

The moral of the story: laziness is good! Since every feature costs, there is sometimes an advantage to waiting until someone asks for a feature before coding it.

About Ben Supnik

Ben is a software engineer who works on X-Plane; he spends most of his days drinking coffee and swearing at the computer -- sometimes at the same time.

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