| Re: [AD] a fix struct for dallegro |
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On Monday 16 April 2007 04:23:35 pm Peter Wang wrote:
> The problem here is not float vs fixed but between different angle
> representations.
Which is inherent in float vs fixed. There's no standard math functions for
floats that use binary angles, and there's no Allegro math functions for
fixed types that use radians. Being able to just change variable types and
add casts doesn't do much to make people aware of these difference though,
IMO.
> Who says I don't want radians stored as fixed point
> values?
No one, and there's nothing stopping you from doing so. But I'd think more
often than not, that won't be the case. Besides which, you'd retain more
precision by using binary angles with a fixed (16 bits + 8 = 24 bits needed,
full range covered) as opposed to radians with a fixed (16 bits + 3 = 19 bits
needed, full range not covered). Plus it's more efficient to use fixed point
math with binary angles than radians.
That as opposed to using radians with a float, where the smaller whole number
would give way to increased decimal precision, and the FPU having op codes
using radians (AFAIK).