71 lines
1.5 KiB
Go
71 lines
1.5 KiB
Go
package main
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import (
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"math"
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)
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type Vector3 struct {
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X, Y, Z float64
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}
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func (u Vector3) Add(v Vector3) Vector3 {
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return Vector3{u.X + v.X, u.Y + v.Y, u.Z + v.Z}
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}
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func (u Vector3) Neg() Vector3 {
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return Vector3{-u.X, -u.Y, -u.Z}
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}
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func (u Vector3) Sub(v Vector3) Vector3 {
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return u.Add(v.Neg())
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}
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func (u Vector3) Scale(a float64) Vector3 {
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return Vector3{a * u.X, a * u.Y, a * u.Z}
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}
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func (u Vector3) Dot(v Vector3) float64 {
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return u.X*v.X + u.Y*v.Y + u.Z*v.Z
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}
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func (u Vector3) Cross(v Vector3) Vector3 {
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return Vector3{u.Y*v.Z - u.Z*v.Y, u.Z*v.X - u.X*v.Z, u.X*v.Y - u.Y*v.X}
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}
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func (u Vector3) LengthSquared() float64 {
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return u.Dot(u)
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}
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func (u Vector3) Length() float64 {
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return math.Sqrt(u.LengthSquared())
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}
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func (u Vector3) Normalized() Vector3 {
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return u.Scale(1.0 / u.Length())
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}
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func (u Vector3) Round() Vector3 {
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round := math.Round
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return Vector3{round(u.X), round(u.Y), round(u.Z)}
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}
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// i incident, n normal. Both vector should be normalized
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func Reflect(i Vector3, n Vector3) Vector3 {
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y := i.Dot(n)
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return i.Add(n.Scale(2 * y))
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}
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// Todo : Refract
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// Rodrigues' rotation formula. rotVector should be normalized
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func rotate(u Vector3, rotVector Vector3, angle float64) Vector3 {
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cos, sin := math.Cos(angle), math.Sin(angle)
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vec1 := u.Scale(cos)
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vec2 := rotVector.Cross(u).Scale(sin)
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vec3 := rotVector.Scale(rotVector.Dot(u) * (1 - cos))
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return vec1.Add(vec2).Add(vec3)
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}
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func (v Vector3) Unpack() (float64, float64, float64) {
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return v.X, v.Y, v.Z
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}
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