Swizzle support

[bitshifter]

It would be good to support generic swizzles.

Ideally this would support swizzling to return the same size vector but a long term goal would be to provide swizzling into a vector of a different size, smaller or larger.

The problem with SSE2 shuffles is the mask needs to be constant. The intrinsic itself is not a const function so I can't provide a method that will take a mask or at least I don't think that's possible. There are a couple of alternatives:

• Generate shuffle methods for all possible permutations. This is what pathfinder does but that's 255 methods for swizzling a Vec4 to another Vec4, potentially more if swizzling to a different size is supported. My main concern with this approach is making sure it doesn't make a mess of the docs.
• Use macros - the underlying __m128 is accessible so I think a macro solution would be possible. I would probably provide vec4_swizzle, vec3_swizzle, and vec2_swizzle so that the type is known and the number of lanes specified in the macro could be used to specify the output size.

[Lokathor]

Just write a program to auto-generate all the swizzles

it's only 4000 lines of code give or take once the program prints it out ;3

[bitshifter]

I wrote a program to generate all the swizzles :)