Rodrigues’ rotation formula: Difference between revisions

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Revision as of 17:37, 29 September 2021

Task

Rotate a point about some axis by some angle.

Described here: https://en.wikipedia.org/wiki/Rodrigues%27_rotation_formula

Perl

!perl -w

use strict; use Math::Trig; # acos use JSON; use constant PI => 3.14159265358979;

Rodrigues' formula for vector rotation - see https://stackoverflow.com/questions/42358356/rodrigues-formula-for-vector-rotation

sub norm {

 my($v)=@_;
 return ($v->[0]*$v->[0] + $v->[1]*$v->[1] + $v->[2]*$v->[2]) ** 0.5;

} sub normalize {

 my($v)=@_;
 my $length = &norm($v);
 return [$v->[0]/$length, $v->[1]/$length, $v->[2]/$length];

} sub dotProduct {

 my($v1, $v2)=@_;
 return $v1->[0]*$v2->[0] + $v1->[1]*$v2->[1] + $v1->[2]*$v2->[2];

} sub crossProduct {

 my($v1, $v2)=@_;
 return [$v1->[1]*$v2->[2] - $v1->[2]*$v2->[1], $v1->[2]*$v2->[0] - $v1->[0]*$v2->[2], $v1->[0]*$v2->[1] - $v1->[1]*$v2->[0]];

} sub getAngle {

 my($v1, $v2)=@_;
 return acos(&dotProduct($v1, $v2) / (&norm($v1)*&norm($v2)))*180/PI;  # remove *180/PI to go back to radians

} sub matrixMultiply {

 my($matrix, $v)=@_;
 return [&dotProduct($matrix->[0], $v), &dotProduct($matrix->[1], $v), &dotProduct($matrix->[2], $v)];

} sub aRotate {

 my($p, $v, $a)=@_;    # point-to-rotate, vector-to-rotate-about, angle(degrees)
 my $ca = cos($a/180*PI);      # remove /180*PI to go back to radians
 my $sa = sin($a/180*PI);
 my $t=1-$ca;
 my($x,$y,$z)=($v->[0], $v->[1], $v->[2]);
 my $r = [
       [$ca + $x*$x*$t, $x*$y*$t - $z*$sa, $x*$z*$t + $y*$sa],
       [$x*$y*$t + $z*$sa, $ca + $y*$y*$t, $y*$z*$t - $x*$sa],
       [$z*$x*$t - $y*$sa, $z*$y*$t + $x*$sa, $ca + $z*$z*$t]
   ];
 return &matrixMultiply($r, $p);

}

my $v1 = [5,-6,4]; my $v2 = [8,5,-30]; my $a = &getAngle($v1, $v2); my $cp = &crossProduct($v1, $v2); my $ncp = &normalize($cp); my $np = &aRotate($v1, $ncp, $a);

my $json=JSON->new->canonical;

print $json->encode($np) . "\n"; # => [ 2.23222107330823, 1.39513817081764, -8.37082902490585 ] = ok. </lang>

JavaScript

function norm(v) {

   return Math.sqrt(v[0]*v[0] + v[1]*v[1] + v[2]*v[2]);

} function normalize(v) {

   var length = norm(v);
   return [v[0]/length, v[1]/length, v[2]/length];

} function dotProduct(v1, v2) {

   return v1[0]*v2[0] + v1[1]*v2[1] + v1[2]*v2[2];

} function crossProduct(v1, v2) {

   return [v1[1]*v2[2] - v1[2]*v2[1], v1[2]*v2[0] - v1[0]*v2[2], v1[0]*v2[1] - v1[1]*v2[0]];

} function getAngle(v1, v2) {

   return Math.acos(dotProduct(v1, v2) / (norm(v1)*norm(v2)));

} function matrixMultiply(matrix, v) {

   return [dotProduct(matrix[0], v), dotProduct(matrix[1], v), dotProduct(matrix[2], v)];

} function aRotate(p, v, a) {

   var ca = Math.cos(a), sa = Math.sin(a), t=1-ca, x=v[0], y=v[1], z=v[2];
   var r = [
       [ca + x*x*t, x*y*t - z*sa, x*z*t + y*sa],
       [x*y*t + z*sa, ca + y*y*t, y*z*t - x*sa],
       [z*x*t - y*sa, z*y*t + x*sa, ca + z*z*t]
   ];
   return matrixMultiply(r, p);

}

var v1 = [5,-6,4]; var v2 = [8,5,-30]; var a = getAngle(v1, v2); var cp = crossProduct(v1, v2); var ncp = normalize(cp); var np = aRotate(v1, ncp, a); console.log(np);

</lang>

Nim

Translation of: Wren

Only changed most function names. <lang Nim>import math

type

 Vector = tuple[x, y, z: float]
 Matrix = array[3, Vector]

func norm(v: Vector): float =

 sqrt(v.x * v.x + v.y * v.y + v.z * v.z)

func normalized(v: Vector): Vector =

 let length = v.norm()
 result = (v.x / length, v.y / length, v.z / length)

func scalarProduct(v1, v2: Vector): float =

 v1.x * v2.x + v1.y * v2.y + v1.z * v2.z

func vectorProduct(v1, v2: Vector): Vector =

 (v1.y * v2.z - v1.z * v2.y, v1.z * v2.x - v1.x * v2.z, v1.x * v2.y - v1.y * v2.x)

func angle(v1, v2: Vector): float =

 arccos(scalarProduct(v1, v2) / (norm(v1) * norm(v2)))

func `*`(m: Matrix; v: Vector): Vector =

 (scalarProduct(m[0], v), scalarProduct(m[1], v), scalarProduct(m[2], v))

func rotate(p, v: Vector; a: float): Vector =

 let ca = cos(a)
 let sa = sin(a)
 let t = 1 - ca
 let r = [(ca + v.x * v.x * t, v.x * v.y * t - v.z * sa, v.x * v.z * t + v.y * sa),
          (v.x * v.y * t + v.z * sa, ca + v.y * v.y * t, v.y * v.z * t - v.x * sa),
          (v.z * v.x * t - v.y * sa, v.z * v.y * t + v.x * sa, ca + v.z * v.z * t)]
 result = r * p

let

 v1 = (5.0, -6.0, 4.0)
 v2 = (8.0, 5.0, -30.0)
 a = angle(v1, v2)
 vp = vectorProduct(v1, v2)
 nvp = normalized(vp)
 np = v1.rotate(nvp, a)

echo np</lang>

Output:

(x: 2.232221073308228, y: 1.395138170817643, z: -8.370829024905852)

Wren

Translation of: JavaScript

<lang ecmascript>var norm = Fn.new { |v| (v[0]*v[0] + v[1]*v[1] + v[2]*v[2]).sqrt }

var normalize = Fn.new { |v|

   var length = norm.call(v)
   return [v[0]/length, v[1]/length, v[2]/length]

}

var dotProduct = Fn.new { |v1, v2| v1[0]*v2[0] + v1[1]*v2[1] + v1[2]*v2[2] }

var crossProduct = Fn.new { |v1, v2|

   return [v1[1]*v2[2] - v1[2]*v2[1], v1[2]*v2[0] - v1[0]*v2[2], v1[0]*v2[1] - v1[1]*v2[0]]

}

var getAngle = Fn.new { |v1, v2| (dotProduct.call(v1, v2) / (norm.call(v1) * norm.call(v2))).acos }

var matrixMultiply = Fn.new { |matrix, v|

   return [dotProduct.call(matrix[0], v), dotProduct.call(matrix[1], v), dotProduct.call(matrix[2], v)]

}

var aRotate = Fn.new { |p, v, a|

   var ca = a.cos
   var sa = a.sin
   var t = 1 - ca
   var x = v[0]
   var y = v[1]
   var z = v[2]
   var r = [
       [ca + x*x*t, x*y*t - z*sa, x*z*t + y*sa],
       [x*y*t + z*sa, ca + y*y*t, y*z*t - x*sa],
       [z*x*t - y*sa, z*y*t + x*sa, ca + z*z*t]
   ]
   return matrixMultiply.call(r, p)

}

var v1 = [5, -6, 4] var v2 = [8, 5,-30] var a = getAngle.call(v1, v2) var cp = crossProduct.call(v1, v2) var ncp = normalize.call(cp) var np = aRotate.call(v1, ncp, a) System.print(np)</lang>

Output:

[2.2322210733082, 1.3951381708176, -8.3708290249059]