Collision Features

Oak uses a fork of rtreego for its collision with extended features like raycasting and trigger functions on collision with labelled entity types.

One of these features allows a programmer to receive collision events when collision begins and ends against certain labels, and another lets a programmer attach collision spaces to vectors so whenever a character moves around they'll take their collision space with them. These two features are demonstrated in the following code and animation of the resulting compiled program:

	package main
	// This is a gist copy of https://github.com/200sc/collision-demo/blob/master/core.go
	import (
	"image/color"
	"bitbucket.org/oakmoundstudio/oak"
	"bitbucket.org/oakmoundstudio/oak/collision"
	"bitbucket.org/oakmoundstudio/oak/entities"
	"bitbucket.org/oakmoundstudio/oak/event"
	"bitbucket.org/oakmoundstudio/oak/render"
	)
	const (
	_ = iota
	RED collision.Label = iota
	GREEN
	BLUE
	TEAL
	)
	func main() {
	oak.AddScene("demo", func(string, interface{}) {
	act := &AttachCollisionTest{}
	act.Solid = entities.NewSolid(50, 50, 50, 50, render.NewColorBox(50, 50, color.RGBA{0, 0, 0, 255}), act.Init())
	collision.Attach(act.Vector, act.Space, 0, 0)
	act.Bind(func(int, interface{}) int {
	if act.ShouldUpdate {
	act.ShouldUpdate = false
	act.R.UnDraw()
	act.R = act.nextR
	render.Draw(act.R, 0)
	}
	if oak.IsDown("A") {
	// We could use attachment here to not have to shift both
	// R and act but that is made more difficult by constantly
	// changing the act's R
	act.ShiftX(-3)
	act.R.ShiftX(-3)
	} else if oak.IsDown("D") {
	act.ShiftX(3)
	act.R.ShiftX(3)
	}
	if oak.IsDown("W") {
	act.ShiftY(-3)
	act.R.ShiftY(-3)
	} else if oak.IsDown("S") {
	act.ShiftY(3)
	act.R.ShiftY(3)
	}
	return 0
	}, "EnterFrame")
	render.Draw(act.R, 0)
	act.R.SetLayer(1)
	collision.PhaseCollision(act.Space)
	act.Bind(func(id int, label interface{}) int {
	l := label.(collision.Label)
	switch l {
	case RED:
	act.r += 125
	act.UpdateR()
	case GREEN:
	act.g += 125
	act.UpdateR()
	case BLUE:
	act.b += 125
	act.UpdateR()
	case TEAL:
	act.b += 125
	act.g += 125
	act.UpdateR()
	}
	return 0
	}, "CollisionStart")
	act.Bind(func(id int, label interface{}) int {
	l := label.(collision.Label)
	switch l {
	case RED:
	act.r -= 125
	act.UpdateR()
	case GREEN:
	act.g -= 125
	act.UpdateR()
	case BLUE:
	act.b -= 125
	act.UpdateR()
	case TEAL:
	act.b -= 125
	act.g -= 125
	act.UpdateR()
	}
	return 0
	}, "CollisionStop")
	upleft := entities.NewSolid(0, 0, 320, 240, render.NewColorBox(320, 240, color.RGBA{100, 0, 0, 100}), 0)
	upleft.Space.UpdateLabel(RED)
	upleft.R.SetLayer(0)
	render.Draw(upleft.R, 0)
	upright := entities.NewSolid(320, 0, 320, 240, render.NewColorBox(320, 240, color.RGBA{0, 100, 0, 100}), 0)
	upright.Space.UpdateLabel(GREEN)
	upright.R.SetLayer(0)
	render.Draw(upright.R, 0)
	botleft := entities.NewSolid(0, 240, 320, 240, render.NewColorBox(320, 240, color.RGBA{0, 0, 100, 100}), 0)
	botleft.Space.UpdateLabel(BLUE)
	botleft.R.SetLayer(0)
	render.Draw(botleft.R, 0)
	botright := entities.NewSolid(320, 240, 320, 240, render.NewColorBox(320, 240, color.RGBA{0, 100, 100, 100}), 0)
	botright.Space.UpdateLabel(TEAL)
	botright.R.SetLayer(0)
	render.Draw(botright.R, 0)
	}, func() bool {
	return true
	}, func() (string, *oak.SceneResult) {
	return "demo", nil
	})
	render.SetDrawStack(
	render.NewHeap(false),
	render.NewDrawFPS(),
	)
	oak.Init("demo")
	}
	type AttachCollisionTest struct {
	entities.Solid
	// AttachSpace is a composable struct that allows
	// spaces to be attached to vectors
	collision.AttachSpace
	// Phase is a composable struct that enables the call
	// collision.CollisionPhase on this struct's space,
	// which will start sending signals when that space
	// starts and stops touching given labels
	collision.Phase
	r, g, b int
	ShouldUpdate bool
	nextR render.Renderable
	}
	func (act *AttachCollisionTest) Init() event.CID {
	cid := event.NextID(act)
	act.CID = cid
	return cid
	}
	func (act *AttachCollisionTest) UpdateR() {
	act.nextR = render.NewColorBox(50, 50, color.RGBA{uint8(act.r), uint8(act.g), uint8(act.b), 255})
	act.nextR.SetPos(act.X(), act.Y())
	act.nextR.SetLayer(1)
	act.ShouldUpdate = true
	}

view raw collisionDemo.go hosted with ❤ by GitHub