Working with mathematical vectors in code is valuable. It requires only math calculation, and a code executing time is faster than a code dependent on a geometrical object attributes.
Maher showed, in a previous post how to extract direction components from an
AxisSystem matrix using EKL. In this post, I’ll dig deeper into how
Vectors work with examples using EKL within a Knowledge Pattern; and within a script node in xGenerative Design.
Vector is an element that has both magnitude and direction. In EKL, there are two
Vector orientations ( column and row).
let v (Vector) //vector in column v = [ 0; 0; 1 ] //vector in row v = [ 0, 0, 1 ]
It is important to know these types when you get x, y, z attributes of vectors
//column vector let x, y, z (Real) x = v.Get(1,1) //x value of v y = v.Get(2,1) //y value of v z = v.Get(3,1) //z value of v //row vector x = v.Get(1,1) //x value of v y = v.Get(1,2) //y value of v z = v.Get(1,3) //z value of v
Also, a column vector will be created by using the method that transforms
Direction into a vector.
let oPlane (Plane) v = direction(oPlane).Vector() let oLine (Line) v = direction(oLine).Vector()
Note: a vector create by 3 Real numbers in xGen will be a row vector
Here are some examples of vector functions.
let v1, v2 (Vector) //input (column vector) let ReturnVec (Vector) //output (column vector) let x, y, z (Real) x = v1.Get(1,1) + v2.Get(1,1) y = v1.Get(2,1) + v2.Get(2,1) z = v1.Get(3,1) + v2.Get(3,1) ReturnVec = [ x; y; z ]
x = v1.Get(1,1) - v2.Get(1,1) y = v1.Get(2,1) - v2.Get(2,1) z = v1.Get(3,1) - v2.Get(3,1) ReturnVec = [ x; y; z ]
x = v1.Get(1,1)*R y = v1.Get(2,1)*R z = v1.Get(3,1)*R ReturnVec = [ x; y; z ]
CrossProduct (already exist in EKL, but just in case)
let CrossProduct (Vector) //output x = v1.Get(2,1)*v2.Get(3,1) - v1.Get(3,1)*v2.Get(2,1) y = v1.Get(3,1)*v2.Get(1,1) - v1.Get(1,1)*v2.Get(3,1) z = v1.Get(1,1)*v2.Get(2,1) - v1.Get(2,1)*v2.Get(1,1) CrossProduct = [ x; y; z ]
let DotProduct (Vector) //output set DotProduct = v1.Get(1,1)*v2.Get(1,1) + v1.Get(2,1)*v2.Get(2,1) + v1.Get(3,1)*v2.Get(3,1)
let Magnitude (Real) //output set Magnitude = sqrt(DotProduct)
Vector Normalize (already exist in EKL, but just in case)
let nv (Vector) //output let Len (Real) Len = abs( sqrt(Magnitude) ) let x, y, z(Real) x = v1.Get(1,1)/Len y = v1.Get(2,1)/Len z = v1.Get(3,1)/Len nv = [ x; y; z ]
By using these function, an angle between vectors is easily found. (There will be another post for calculating rotation angle)
let vAngle (ANGLE) //output //step 1: create unit vectors of v1 and v2 let nv1, nv2 (Vector) //step 2: dotproduct of nv1 and nv2 let dot (Real) vAngle = acos(dot)
Rotating vector is also easily created by following steps.
//step 1: create unit vector of original vector and rotation axis vector let nv, nAxis (Vector) //step 2: extract x, y, and z attributes of Axis unit vector let x, y, z (Real) x = nAxis.Get(1,1) y = nAxis.Get(2,1) z = nAxis.Get(3,1) //step 3: get real number of rotation angle(convert ANGLE to String to Real) let rAngle (Real) //step 4: find radian let rad (Real) rad = rAngle*PI /180 //step 5: find cosin, sin, and tangent let c, s, t (Real) c = cos(rad) s = sin(rad) t = 1-cos(rad) //step 6: get transformed(ratated) value of x, y, and z attributes let vx, vy, vz (Real) vx = nv.Get(1,1)*(t*x*x + c) + nv.Get(2,1)*(t*x*y - s*z) + nv.Get(3,1)*(t*x*z + s*y) vy = nv.Get(1,1)*(t*x*y + s*z) + nv.Get(2,1)*(t*y*y + c) + nv.Get(3,1)*(t*y*z - s*x) vz = nv.Get(1,1)*(t*x*z - s*y) + nv.Get(2,1)*(t*y*z + s*x) + nv.Get(3,1)*(t*z*z + c) let vReturn (Vector) //output vReturn = [vx; vy; vz]
3D BI-ARC Example
Here is an example of creation by using vectors via Knowledge Patterns and xGen’s script node.
BI-ARC using Knowledge Pattern with custom control.
xGenerative Design Script Node
BI-ARC using Script Editor in xGen with custom control.
Here is the file used for the above example
Hits: 162Tags: EKL, Knowledge Pattern, Linear Algebra, xGenerative Design