blob: 163903fcb1d91885ab2243bd7f4887a8e5595c6f [file] [log] [blame]
 // Copyright ©2019 The Gonum Authors. All rights reserved. // Use of this source code is governed by a BSD-style // license that can be found in the LICENSE file. package r3 import "math" // Vec is a 3D vector. type Vec struct { X, Y, Z float64 } // Add returns the vector sum of p and q. func (p Vec) Add(q Vec) Vec { p.X += q.X p.Y += q.Y p.Z += q.Z return p } // Sub returns the vector sum of p and -q. func (p Vec) Sub(q Vec) Vec { p.X -= q.X p.Y -= q.Y p.Z -= q.Z return p } // Scale returns the vector p scaled by f. func (p Vec) Scale(f float64) Vec { p.X *= f p.Y *= f p.Z *= f return p } // Dot returns the dot product p·q. func (p Vec) Dot(q Vec) float64 { return p.X*q.X + p.Y*q.Y + p.Z*q.Z } // Cross returns the cross product p×q. func (p Vec) Cross(q Vec) Vec { return Vec{ p.Y*q.Z - p.Z*q.Y, p.Z*q.X - p.X*q.Z, p.X*q.Y - p.Y*q.X, } } // Norm returns the Euclidean norm of p // |p| = sqrt(p_x^2 + p_y^2 + p_z^2). func Norm(p Vec) float64 { return math.Hypot(p.X, math.Hypot(p.Y, p.Z)) } // Norm returns the Euclidean squared norm of p // |p|^2 = p_x^2 + p_y^2 + p_z^2. func Norm2(p Vec) float64 { return p.X*p.X + p.Y*p.Y + p.Z*p.Z } // Unit returns the unit vector colinear to p. // Unit returns {NaN,NaN,NaN} for the zero vector. func Unit(p Vec) Vec { if p.X == 0 && p.Y == 0 && p.Z == 0 { return Vec{X: math.NaN(), Y: math.NaN(), Z: math.NaN()} } return p.Scale(1 / Norm(p)) } // Cos returns the cosine of the opening angle between p and q. func Cos(p, q Vec) float64 { return p.Dot(q) / (Norm(p) * Norm(q)) } // Box is a 3D bounding box. type Box struct { Min, Max Vec }