undefined | Better HN

0 pointssigna119y ago0 comments

having written one as a slightly larger python thingy, i can fully attest to that.

now that it is kind of done, i want to make it faster :) for example, having a home-grown vector_3d class kind of sucks (performance wise). it might be better to have vector_3d be actually based on, say, numpy.array ? once that is done, and i start seeing some real improvement, it might be possible to go the other route as well i.e. write the hot-spots in c++/c, and interface that with python.

or go with lua all the way ? or maybe try a hybrid approach (which would allow you to see how embeddable the language really is)

possibilities are endless, and as you so rightly said, gratification is instantaneous :)

0 comments

Marazan9y ago

Simply replacing your own vector_3d class with numpy.array() won't actually speed you up that much as the overhead of creating all the tiny 3 element arrays kills you (I think I got only a 2x speed up from going from a pure python vector_3d to numpy arrays). Numpy is optimised for the creation of a small number of big arrays.

The massive enormous speed ups come from creating massive arrays and implicitly working on them in parallel. So instead of iterating through every pixel and creating a origin and direction vector for each one you create a Total_number_of_pixels X 3 numpy array and pass that to your ray tracing function. Due to the way numpy broadcasts arrays the amount of rewriting you need to do is incredibly minimal and the speed ups over pure python are astronomical.

signa11OP9y ago

> The massive enormous speed ups come from creating massive arrays and implicitly working on them in parallel. So instead of iterating through every pixel and creating a origin and direction vector for each one you create a Total_number_of_pixels X 3 numpy array and pass that to your ray tracing function. Due to the way numpy broadcasts arrays the amount of rewriting you need to do is incredibly minimal and the speed ups over pure python are astronomical.

thank you for your insight! this is very useful indeed.

Marazan9y ago

Just to give an idea of the speed up from going from processing individual arrays to batch processing - an Image I was rendering went from 2 hours to 20 seconds (and that was with further obvious speed ups left on the table as well).

Oh, and make sure you're using 64-bit version of python as you'll be slinging multi-gigabyte arrays around all over the place.

j / k navigate · click thread line to collapse

0 pointssigna119y ago0 comments

having written one as a slightly larger python thingy, i can fully attest to that.

or go with lua all the way ? or maybe try a hybrid approach (which would allow you to see how embeddable the language really is)

possibilities are endless, and as you so rightly said, gratification is instantaneous :)

0 comments

Marazan9y ago

signa11OP9y ago

thank you for your insight! this is very useful indeed.

Marazan9y ago

Oh, and make sure you're using 64-bit version of python as you'll be slinging multi-gigabyte arrays around all over the place.

j / k navigate · click thread line to collapse