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Better to_euler_rotation methods

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This commit is contained in:
Lars Mueller 2021-02-06 11:57:34 +01:00
parent a462b313f1
commit 525f0dc2de
1 changed files with 37 additions and 7 deletions
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44
quaternion.lua
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@ -65,21 +65,51 @@ function to_euler_rotation(self)
local rotation = {}
local sinr_cosp = 2 * (self[4] * self[1] + self[2] * self[3])
local cosr_cosp = 1 - 2 * (self[1] * self[1] + self[2] * self[2])
local cosr_cosp = 1 - 2 * (self[1] ^ 2 + self[2] ^ 2)
rotation.x = math.atan2(sinr_cosp, cosr_cosp)
local sinp = 2 * (self[4] * self[2] - self[3] * self[1])
if sinp <= -1 then
rotation.y = -math.pi/2
rotation.z = -math.pi/2
elseif sinp >= 1 then
rotation.y = math.pi/2
rotation.z = math.pi/2
else
rotation.y = math.asin(sinp)
end
rotation.z = math.asin(sinp)
end
local siny_cosp = 2 * (self[4] * self[3] + self[1] * self[2])
local cosy_cosp = 1 - 2 * (self[2] * self[2] + self[3] * self[3])
rotation.z = math.atan2(siny_cosp, cosy_cosp)
local cosy_cosp = 1 - 2 * (self[2] ^ 2 + self[3] ^ 2)
rotation.y = math.atan2(siny_cosp, cosy_cosp)
return vector.apply(rotation, math.deg)
end
-- See https://github.com/zaki/irrlicht/blob/master/include/quaternion.h#L652
function to_euler_rotation_irrlicht(self)
local x, y, z, w = unpack(self)
local test = 2 * (y * w - x * z)
local function _calc()
if math.abs(test - 1) <= 1e-6 then
return {
z = -2 * math.atan2(x, w),
x = 0,
y = math.pi/2
}
end
if math.abs(test + 1) <= 1e-6 then
return {
z = 2 * math.atan2(x, w),
x = 0,
y = math.pi/-2
}
end
return {
z = math.atan2(2 * (x * y + z * w), x ^ 2 - y ^ 2 - z ^ 2 + w ^ 2),
x = math.atan2(2 * (y * z + x * w), -x ^ 2 - y ^ 2 + z ^ 2 + w ^ 2),
y = math.asin(math.min(math.max(test, -1), 1))
}
end
return vector.apply(_calc(), math.deg)
end