VFPU: Ensure that sin(4*x) returns 0.0 (and cos 1) for all x. Fixes #2921 #6329
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Was just perusing the comments in #2921, and that was some fine investigative work that led to the solution by @unknownbrackets (even if I didn't understand most of it, was not a math major in college, heh.) Just wanted to point that out. |
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Ah yes, sorry :) I did compliment unknown on his work in the thread though :) |
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cause logic problem in Saint Seiya Omega. |
| angle -= floorf(angle * 4.0f) * 0.25f; | ||
| angle *= (float)M_PI_2; | ||
| sine = sinf(angle); | ||
| cosine = cosf(angle); |
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Android has sincosf() these days (latest ndks) right? Though not sure what our build req is.
-[Unknown]
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Is the buildbot upgraded to the latest?
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Last I checked it seemed to have ndk-r9b, from October 2013.
https://code.google.com/p/android/issues/detail?id=38423
Was marked "released" October 31, 2013. Not sure if that means it's in b or c...
-[Unknown]
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I think it didn't actually make it until d, but not sure. Maybe c. Pretty sure not b.
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also bug in tekken 6 |
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| inline void vfpu_sincos(float angle, float &sine, float &cosine) { | ||
| angle -= floorf(angle * 4.0f) * 0.25f; |
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Hmm, not sure this is rounding right?
Angle 1 = 1_pi/2 = sin=1,cos=0
Angle 2 = 2_pi/2 = sin=0,cos=-1
Angle 3 = 3_pi/2 = sin=-1,cos=0
Angle 4 = 4_pi/2 = sin=0,cos=1
However, 3 - floor(3 * 4) * 0.25 = 3 - 12 * 0.25 = 0. Should be * 0.25 / 4, right?
-[Unknown]
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Hmm, oops. Logic shortcircuit in my brain, heh. Will fix. |
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Problems have been fixed. |
VFPU: Ensure that sin(4*x) returns 0.0 (and cos 1) for all x. Fixes #2921
This also makes it easier to replace our VFPU sin/cos implementations with some approximation later.
Note that our sinf/cosf function replacements should not call these, they are expected to behave like libc sinf/cosf, I would think.
Fixes #2921