convert.go

package engoBox2dSystem

import (
	"engo.io/engo"
	"engo.io/engo/math"

	"github.com/ByteArena/box2d"
)

//Convert handles conversion between the space component and the Box2d World
type Convert struct {
	// PixelsPerMeter is how many pixels in the space component are in one meter in the Box2d World
	PixelsPerMeter float32
}

// Conv is the internal converter used by the system. Use this rather than create your own,
// but you can change the pixels per meter here and it'll change it for all the systems too.
var Conv = &Convert{20}

// ToEngoPoint converts a box2d.B2Vec2 into an engo.Point
//
// note that the units are converted, not just copying values
func (c *Convert) ToEngoPoint(vec box2d.B2Vec2) engo.Point {
	return engo.Point{
		X: c.MetersToPx(vec.X),
		Y: c.MetersToPx(vec.Y),
	}
}

// ToBox2d2Vec converts an engo.Point into a box2d.B2Vec2
//
// note that the units are converted, not just copying values
func (c *Convert) ToBox2d2Vec(pt engo.Point) box2d.B2Vec2 {
	return box2d.B2Vec2{
		X: c.PxToMeters(pt.X),
		Y: c.PxToMeters(pt.Y),
	}
}

// PxToMeters converts from the space component's px to Box2d's meters
func (c *Convert) PxToMeters(px float32) float64 {
	return float64(px / c.PixelsPerMeter)
}

// MetersToPx converts from Box2d's meters to the space component's pixels
func (c *Convert) MetersToPx(m float64) float32 {
	return float32(m) * c.PixelsPerMeter
}

// RadToDeg converts from radians to degrees
func (c *Convert) RadToDeg(r float64) float32 {
	return float32(r*180) / math.Pi
}

// DegToRad converts from degrees to radians
func (c *Convert) DegToRad(d float32) float64 {
	return float64(d * math.Pi / 180)
}