Christoph Ruegg
11 years ago
7 changed files with 166 additions and 0 deletions
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module MathNet.Numerics.Quaternion |
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//Reference: |
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//http://www.astro.rug.nl/software/kapteyn/_downloads/attitude.pdf |
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//http://www.mathworks.com/help/aeroblks/quaternionmultiplication.html |
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//http://www.mathworks.com/help/aeroblks/quaterniondivision.html |
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//https://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation#The_conjugation_operation |
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type Quaternion = |
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{ |
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w:float |
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x:float |
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y:float |
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z:float |
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} with |
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static member (+) (r: Quaternion, q: Quaternion) = |
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{w=r.w+q.w;x=r.x+q.x;y=r.y+q.y;z=r.z+q.z} |
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static member (-) (r: Quaternion, q: Quaternion) = |
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{w=r.w-q.w;x=r.x-q.x;y=r.y-q.y;z=r.z-q.z} |
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static member (*) (r: Quaternion, q: Quaternion) = |
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let w = r.w*q.w - r.x*q.x - r.y*q.y - r.z*q.z |
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let x = r.w*q.x + r.x*q.w - r.y*q.z + r.z*q.y |
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let y = r.w*q.y + r.x*q.z + r.y*q.w - r.z*q.x |
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let z = r.w*q.z - r.x*q.y + r.y*q.x + r.z*q.w |
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{w=w;x=x;y=y;z=z} |
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static member (/) (r: Quaternion, q: Quaternion) = |
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let d = (r.w**2.0 + r.x**2.0 + r.y**2.0 + r.z**2.0) |
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let w = (r.w*q.w + r.x*q.x + r.y*q.y + r.z*q.z) / d |
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let x = (r.w*q.x - r.x*q.w - r.y*q.z + r.z*q.y) / d |
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let y = (r.w*q.y + r.x*q.z - r.y*q.w - r.z*q.x) / d |
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let z = (r.w*q.z - r.x*q.y + r.y*q.x - r.z*q.w) / d |
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{w=w;x=x;y=y;z=z} |
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static member (/) (q:Quaternion, a) = |
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{w=q.w/a; x=q.x/a;y=q.y/a;z=q.z/a} |
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let norm q = |
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q.w**2.0 + q.x**2.0 + q.y**2.0 + q.z**2.0 |
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let normalize q = |
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let invNorm = 1.0 / (norm q |> sqrt) |
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{w=q.w*invNorm;x=q.x*invNorm;y=q.y*invNorm;z=q.z*invNorm} |
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let conjugate q = |
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{w=q.w; x= -q.x; y= -q.y; z= -q.z} |
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let inverse q = |
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conjugate q / norm q |
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//create a new quaternion |
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//angle in radians |
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//http://www.astro.rug.nl/software/kapteyn/_downloads/attitude.pdf |
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//6.12 Unit Quaternion ⇐ Axis-Angle |
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// _ _ |
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// qa (α, n) := | cos α/2 | |
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// | n sin α/2 | |
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// - - |
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let create (angle:float) (x:float) (y:float) (z:float) = |
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//axis needs to be unit vector |
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let vNorm = x**2.0+y**2.0+z**2.0 |
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let invNorm = 1.0 / (vNorm |> sqrt) |
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let x' = x*invNorm |
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let y' = y*invNorm |
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let z' = z*invNorm |
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let halfAngle = angle * 0.5 |
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let s = halfAngle |> sin |
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let c = halfAngle |> cos |
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{w=c; x=x'*s; y=y'*s; z=z'*s} |
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//dot product |
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let dot q1 q2 = |
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q1.w*q2.w + q1.x * q2.x + q1.y * q2.y + q1.z * q2.z |
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//rotate a vector(x,y,z) by a quaternion |
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// p is a pure quaternion(i.e w=0.0) |
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// p' = qpq**-1.0 |
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// https://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation#The_conjugation_operation |
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let rotate q1 x y z = |
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let q = normalize q1 //ensure unit quaternion |
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let p = {w=0.0; x=x; y=y; z=z} |
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q * p * inverse q |
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/// <summary> |
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/// Concatenates two Quaternions; the result represents the value1 rotation followed by the value2 rotation. |
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/// </summary> |
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/// <param name="value1">The first Quaternion rotation in the series.</param> |
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/// <param name="value2">The second Quaternion rotation in the series.</param> |
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/// <returns>A new Quaternion representing the concatenation of the value1 rotation followed by the value2 rotation.</returns> |
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let concat (q:Quaternion) (q':Quaternion) = q' * q //concat rotation is actually q' * q instead of q * q'. |
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@ -0,0 +1,69 @@ |
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namespace MathNet.Numerics.Tests |
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open System |
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open NUnit.Framework |
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open FsUnit |
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open MathNet.Numerics.Quaternion |
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module QuaternionTests = |
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//simple quaternions |
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let n = {w=1.0;x=0.0;y=1.0;z=0.0} |
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let n' = {w= 0.5;x= -0.5;y= 0.5;z= 0.0} |
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//less simple quaternions |
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let r = {w=1.0;x=2.0;y=3.0;z=4.0} |
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let q = {w= -4.0;x= 3.0; y= -2.0; z= 1.0} |
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[<Test>] |
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let ``Quaternion.create`` () = |
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let fourtyFiveDegreesInRadians = 45.0 * Math.PI / 180.0 |
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create fourtyFiveDegreesInRadians 1.0 0.0 0.0 |> |
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should equal {w = 0.92387953251128674; x = 0.38268343236508978; y = 0.0; z = 0.0;} |
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[<Test>] |
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let ``Quaternion.create normalizes input vector`` () = |
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let fourtyFiveDegreesInRadians = 45.0 * Math.PI / 180.0 |
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create fourtyFiveDegreesInRadians 100.0 0.0 0.0 |> |
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should equal <| |
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create fourtyFiveDegreesInRadians 1.0 0.0 0.0 |
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[<Test>] |
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let ``Quaternion.+`` () = |
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n + n' |> should equal {w= 1.5;x= -0.5;y= 1.5;z= 0.0} |
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[<Test>] |
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let ``Quaternion.-`` () = |
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n - n' |> should equal {w= 0.5;x= 0.5;y= 0.5;z= 0.0} |
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[<Test>] |
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let ``Quaternion.* r*q'`` () = |
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r * q |> should equal {w = -8.0; x = -16.0; y = -24.0; z = -2.0;} |
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[<Test>] |
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let ``Quaternion.* q*r`` () = |
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q * r |> should equal {w = -8.0; x = 6.0; y = -4.0; z = -28.0;} |
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//http://www.mathworks.com/help/aerotbx/ug/quatnorm.html |
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[<Test>] |
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let ``Quaternion.Norm`` () = |
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norm n' |> should equal 0.75 |
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//http://www.mathworks.com/help/aerotbx/ug/quatnormalize.html |
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[<Test>] |
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let ``Quaternion.Normalize`` () = |
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normalize n |> should equal {w= 0.70710678118654746; x= 0.0; y= 0.70710678118654746; z= 0.0} |
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//http://www.mathworks.com/help/aerotbx/ug/quatinv.html |
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[<Test>] |
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let ``Quaternion.Inverse`` () = |
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inverse n |> should equal {w= 0.5;x= 0.0;y= -0.5;z= 0.0} |
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//http://www.mathworks.com/help/aerotbx/ug/quatconj.html |
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[<Test>] |
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let ``Quaternion.Conjugate`` () = |
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conjugate n |> should equal {w= 1.0;x= 0.0;y= -1.0;z= 0.0} |
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//http://www.mathworks.com/help/aerotbx/ug/quatrotate.html |
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[<Test>] |
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let ``Quaternion.Rotate`` () = |
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rotate n 1.0 1.0 1.0 |> should equal {w= 0.0;x= -1.0;y= 1.0;z= 1.0} |
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