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phetsims / dot

A math library with a focus on mutable and immutable linear algebra for 2D and 3D applications.
MIT License
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Improvements for Ray2 #39

Closed samreid closed 9 years ago

samreid commented 9 years ago

@jonathanolson suggested that I look into using Ray2 for some math in bending light. It is looking good but I have some questions about Ray2:

First, why does it store the direction as a 2d vector instead of an angle? It only has 3 degrees of freedom, so why store 4 values and require that the 4th value not be independent (in an assertion check?)

Second: the fields are called pos and dir. It may be better to call them position and direction to be consistent with the rest of the nickname-less code, especially since they are public.

pixelzoom commented 9 years ago

+1 for using full names (position and direction).

jonathanolson commented 9 years ago

First, why does it store the direction as a 2d vector instead of an angle? It only has 3 degrees of freedom, so why store 4 values and require that the 4th value not be independent (in an assertion check?)

I've found that using the unit vector for direction is generally much easier. A common case is stepping a ray forward by a fixed amount (position + multiplier * direction), which would be (position + trig expression). Also most intersection routines for rays involve the unit vector for direction more often than any sort of "angle" is used.

Second: the fields are called pos and dir. It may be better to call them position and direction to be consistent with the rest of the nickname-less code, especially since they are public.

Sounds great to me, it was mostly a hold-over from other code I've written many years ago. I'll take care of this.

jonathanolson commented 9 years ago

Anything left to do here, and can you review my changes?

samreid commented 9 years ago

The changes above look good. Shall we do the same thing for Ray3?

samreid commented 9 years ago

Also, the other thing I would suggest is running the sim tests to see if we missed anything. @jonathanolson do you have time to start that up or should I?

jonathanolson commented 9 years ago

Sounds good to both test and handle Ray3. I'll be able to take care of that at home.

jonathanolson commented 9 years ago

Done, tested usages of Ray3.