Hi - vfx/games programmer here - I've never been given FizzBuzz - although similar problems generally appear on any programming test I've seen (reverse a string, find loop in linked list etc.) the better ones I've seen a couple of times now are:
"How do you reflect a vector about a normal? Name some uses."
"What is the dot product? Name some uses."
These aren't just filters but an experienced real-time rendering or physics programmer is going to have quite a lot to say about the practical implementations of either in particular situations and what hardware features are available to help you with them...
if there is a good theoretical understanding then they can talk a lot about what the dot product is, its relationship to matrix multiplication and tensor inner products in general. they can explain multiple approaches to the problem of reflecting the vector and derive their solutions from first principles instead of just repeating remembered knowledge.
there are lots of little domain specific bits of knowledge as well e.g. the reflection question can lead to discussion of the Blinn half angle approximation - why it works and why its no longer a particularly valid optimisation on today's hardware - the dot product question can lead to discussion of how to efficiently handle solving a quadratic equation on the GPU
really i expect a decent (games/vfx) programmer to run out of time whilst elaborating on answers to either of these questions (although not to the detriment of the rest of the test of course...).
the best filter is a strong demo though imo. never met a bad programmer who has a decent demo... none of the average, lazy or bad programmers i've worked with have one that i couldn't have crapped out in the evening before an interview.
"How do you reflect a vector about a normal? Name some uses."
"What is the dot product? Name some uses."
These aren't just filters but an experienced real-time rendering or physics programmer is going to have quite a lot to say about the practical implementations of either in particular situations and what hardware features are available to help you with them...
if there is a good theoretical understanding then they can talk a lot about what the dot product is, its relationship to matrix multiplication and tensor inner products in general. they can explain multiple approaches to the problem of reflecting the vector and derive their solutions from first principles instead of just repeating remembered knowledge.
there are lots of little domain specific bits of knowledge as well e.g. the reflection question can lead to discussion of the Blinn half angle approximation - why it works and why its no longer a particularly valid optimisation on today's hardware - the dot product question can lead to discussion of how to efficiently handle solving a quadratic equation on the GPU
really i expect a decent (games/vfx) programmer to run out of time whilst elaborating on answers to either of these questions (although not to the detriment of the rest of the test of course...).
the best filter is a strong demo though imo. never met a bad programmer who has a decent demo... none of the average, lazy or bad programmers i've worked with have one that i couldn't have crapped out in the evening before an interview.