math_nodeps.go

//go:build !gmath

package input

import (
	"math"
)

// We're not using any math/vector library to make it possible for the users
// to use any kind of math library they like without having to have more
// than one math library inside their project.
//
// This means that we'll have to implement some math here,
// but it's worth it.

// Vec is a simple wrapper around a pair of float64 coordinates.
//
// Since most games use float values for most values, input library
// converts int pair to the float pair once per Update() call so
// all usages inside the frame can use already converted values.
//
// We're not using some vector2d library to avoid extra dependencies.
// It should be easy to convert this Point object into any other structure.
type Vec struct {
	X float64
	Y float64
}

func vecDistance(v, v2 Vec) float64 {
	return math.Sqrt((v.X-v2.X)*(v.X-v2.X) + (v.Y-v2.Y)*(v.Y-v2.Y))
}

func vecDot(v, v2 Vec) float64 {
	return (v.X * v2.X) + (v.Y * v2.Y)
}

func vecLenSquared(v Vec) float64 {
	return vecDot(v, v)
}

func vecLen(v Vec) float64 {
	return math.Sqrt(vecLenSquared(v))
}

func vecAngle(v Vec) float64 {
	return math.Atan2(v.Y, v.X)
}

func angleNormalized(radians float64) float64 {
	radians -= math.Floor(radians/(2*math.Pi)) * 2 * math.Pi
	return radians
}