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better clamping to prevent gimbal lock? #459

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12 changes: 7 additions & 5 deletions Graphics/Implicit/Definitions.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -78,7 +78,7 @@ where

import GHC.Generics (Generic)

import Prelude (Foldable, Num, Ord, Eq, atan2, asin, pi, (>=), signum, abs, (+), (-), RealFloat, (==), ($), flip, Semigroup((<>)), Monoid (mempty), Double, Either(Left, Right), Bool(True, False), (*), (/), fromIntegral, Float, realToFrac, (&&), RealFloat(isNaN), (||), any)
import Prelude (Foldable, Num, Ord, Eq, atan2, asin, (>=), abs, (+), (-), RealFloat, (==), ($), flip, Semigroup((<>)), Monoid (mempty), Double, Either(Left, Right), Bool(True, False), (*), (/), fromIntegral, Float, realToFrac, (&&), RealFloat(isNaN), (||), any, max, min, otherwise)

import Graphics.Implicit.FastIntUtil as F (Fastℕ(Fastℕ), fromFastℕ, toFastℕ)

Expand Down Expand Up @@ -420,12 +420,14 @@ quaternionToEuler (Quaternion w (V3 x y z))=
let sinr_cosp = 2 * (w * x + y * z)
cosr_cosp = 1 - 2 * (x * x + y * y)
sinp = 2 * (w * y - z * x);
-- A clamped sinp, for precision.
sinp_clamped = max (-1) (min 1 sinp)
pitch = asin sinp_clamped
roll
| abs sinp_clamped >= 1 = 0 -- handle gimble lock.
| otherwise = atan2 sinr_cosp cosr_cosp
siny_cosp = 2 * (w * z + x * y);
cosy_cosp = 1 - 2 * (y * y + z * z);
pitch = if abs sinp >= 1
then signum sinp * pi / 2
else asin sinp
roll = atan2 sinr_cosp cosr_cosp
yaw = atan2 siny_cosp cosy_cosp
in V3 roll pitch yaw

Expand Down