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path: root/vec3d.go
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package main

import "math"

type Vec3D struct {
	x, y, z float64
}

func (vec Vec3D) Invert() Vec3D {
	return Vec3D{-vec.x, -vec.y, -vec.z}
}

func (vec Vec3D) Length() float64 {
	return math.Sqrt(DotProduct(vec, vec))
}

func (vec Vec3D) Unit() Vec3D {
	length := vec.Length()
	if length == 0 {
		return vec
	}
	return ScalarProduct(1.0/length, vec)
}

func AddVec3D(vec1 Vec3D, vec2 Vec3D) Vec3D {
	return Vec3D{vec1.x + vec2.x, vec1.y + vec2.y, vec1.z + vec2.z}
}

func SubVec3D(vec1 Vec3D, vec2 Vec3D) Vec3D {
	return AddVec3D(vec1, vec2.Invert())
}

func ScalarProduct(scalar float64, vec Vec3D) Vec3D {
	return Vec3D{scalar * vec.x, scalar * vec.y, scalar * vec.z}
}

func DotProduct(vec1 Vec3D, vec2 Vec3D) float64 {
	return vec1.x*vec2.x + vec1.y*vec2.y + vec1.z*vec2.z
}

func CrossProduct(vec1 Vec3D, vec2 Vec3D) Vec3D {
	return Vec3D{
		vec1.y*vec2.z - vec1.z*vec2.y,
		vec1.z*vec2.x - vec1.x*vec2.z,
		vec1.x*vec2.y - vec1.y*vec2.x,
	}
}