3d/main.go

package main

import (
	"fmt"
	"math"
	"math/rand"

	rl "github.com/gen2brain/raylib-go/raylib"
)

const (
	blocksNumber   = 10
	buildsPerBlock = 10
	totalBuildings = 1024
	// totalBuildings           = 1
	MARGIN                   = 20
	WIDTH                    = 1100
	HEIGHT                   = 700
	buildingSpacing          = 18
	buildingSize             = 8
	maxBuildingHeight        = 60
	maxColumns               = 5
	enemyAcc                 = 0.01
	maxSpeed                 = 0.1
	buildingsHealth          = 20
	oneSecond         second = 1
)

var gravity = rl.NewVector3(0, -2, 0)

// var globalParticles []Particle

type object struct {
	pos rl.Vector3
}

func (b *object) Pos() rl.Vector3 { return b.pos }

type livingObject struct {
	object
	health int
}

func (o *livingObject) IsAlive() bool          { return o.health <= 0 }
func (o *livingObject) Life() int              { return o.health }
func (o *livingObject) CauseDamage(damage int) { o.health -= damage }

type kinecticObject struct {
	object
	speed rl.Vector3
}

type shootingEnemy struct {
	livingObject
	dodgeDelay float64
	animate    animationFunc
	color      rl.Color
	fireRate   *timer
}

type projectile struct {
	kinecticObject
	destroyed bool
}

type bombProjectile struct {
	projectile
}

type missileProjectile struct {
	projectile
}

type animationOver bool
type animationFunc func() animationOver

type building struct {
	object
	size        rl.Vector3
	color       rl.Color
	life        int
	boundingBox rl.BoundingBox
	animate     animationFunc
}

type healthBar struct {
	life        int
	damageTaken float32
	lastUpdate  float64
	pos         Somewhere
}

type character struct {
	camera rl.Camera
	damage int
	life   int
}

type scene struct {
	things []DrawableLivingThing
	// buildings   []Building
	healthBar *healthBar
	// projectiles []*projectile
	character Player
	particles []Particle
	// enemies     []Enemy
	// emitters    []Emitter
}

func (s *scene) AppendThing(t ...DrawableLivingThing) { s.things = append(s.things, t...) }
func (s *scene) AppendParticle(p ...Particle)         { s.particles = append(s.particles, p...) }

func GetThing[T DrawableLivingThing](s *scene) []T {
	var ret []T
	for _, thing := range s.things {
		if conv, ok := thing.(T); ok && conv.IsAlive() {
			ret = append(ret, conv)
		}
	}
	return ret
}

func (s *scene) Buildings() []Building {
	b := GetThing[*building](s)
	var r []Building = make([]Building, len(b))
	for i := range b {
		r[i] = b[i]
	}
	return r
}

func (s *scene) Enemies() []Enemy {
	return GetThing[Enemy](s)
}

type second float64

type timer struct {
	ttl   second
	time  float32
	start float64
}

func (t *timer) tick() {
	t.time += rl.GetFrameTime()
}

// tick, timeout, reset
func (t *timer) ttr() bool {
	t.tick()
	if t.isTimeout() {
		t.reset()
		return true
	}
	return false
}

func (t *timer) isTimeout() bool {
	return t.time >= float32(t.ttl)
}

func (t *timer) reset() {
	t.start = float64(t.time)
	t.time = 0
}

func (t *timer) unit() float32 {
	return t.time / float32(t.ttl)
}

func newTimer(duration second) *timer {
	return &timer{time: 0, ttl: duration, start: rl.GetTime()}
}

func newTimerWithStartDelay(duration, delay second) *timer {
	return &timer{time: float32(delay), ttl: duration, start: rl.GetTime()}
}

type Thing interface {
	Update()
}

type Somewhere interface {
	Pos() rl.Vector3
}

type Drawable interface {
	Draw()
}

type Living interface {
	IsAlive() bool
	Life() int
	CauseDamage(int)
}

type DrawableLivingThing interface {
	Collide
	Drawable
	Living
	Thing
	Somewhere
}

type Animate interface {
	Animation() animationFunc
	Animate() animationOver
	SetAnimation(animationFunc)
}

type Collide interface {
	RayCollision(rl.Ray) rl.RayCollision
	SphereCollision(centerSphere rl.Vector3, radiusSphere float32) bool
}

type Particle interface {
	Thing
	Living
	Drawable
}

type Enemy interface {
	Collide
	Thing
	Drawable
	Living
	Somewhere
	Animate
}

type Player interface {
	Somewhere
	Thing
	// Drawable
	Living
}

type Building interface {
	Somewhere
	Thing
	Drawable
	Living
	Animate
	Collide
}

// type Emitter interface {
// 	Alive
// 	Drawable
// 	Update() int
// }

type simpleEmitter struct {
	particles      []Particle
	pos            rl.Vector3
	particleAmount int
}

type explosionEmitter struct {
	simpleEmitter
}

type simpleParticle struct {
	// birth float32
	lifetime float64
	pos      rl.Vector3
	speed    rl.Vector3
}

type explosionParticle struct {
	simpleParticle
	trailTimer *timer
}

type smokeTrailParticle struct {
	simpleParticle
}

var city *scene

func NewHealthBar(where Somewhere) *healthBar {
	return &healthBar{pos: where}
}

func NewShootingEnemy(pos rl.Vector3, health int) Enemy {
	return &shootingEnemy{
		dodgeDelay:   rand.Float64() * 3.1,
		fireRate:     newTimerWithStartDelay(0.5, second(rand.Float64()*10.1)),
		livingObject: livingObject{object: object{pos: pos}, health: health},
	}
}

func (e *shootingEnemy) RayCollision(ray rl.Ray) rl.RayCollision {
	return rl.GetRayCollisionSphere(ray, e.pos, 1)
}

func (e *shootingEnemy) SphereCollision(centerSphere rl.Vector3, radiusSphere float32) bool {
	return rl.CheckCollisionSpheres(e.pos, 1, centerSphere, radiusSphere)

}

func (e *shootingEnemy) Animate() animationOver {
	if e.animate != nil {
		return e.animate()
	} else {
		return true
	}
}

func (e *shootingEnemy) Animation() animationFunc {
	return e.animate
}

func (e *shootingEnemy) SetAnimation(f animationFunc) {
	e.animate = f
}

func (e *shootingEnemy) CauseDamage(damage int) {
	e.health -= damage
	e.animate = shakeEnemy(e)
}

func (e *shootingEnemy) IsAlive() bool {
	return e.health > 0 || e.animate != nil
}

func (e *shootingEnemy) Draw() {
	if e.Animation() != nil {
		if over := e.Animate(); over {
			e.SetAnimation(nil)
		}
		return
	}
	playerDirection := rl.NewVector3(0, 1, 0)
	rl.DrawSphere(e.Pos(), 1, rl.Red)
	rl.DrawLine3D(e.pos, rl.Vector3Add(e.pos, rl.Vector3Scale(playerDirection, 40)), rl.Blue)
}

func raycast(pos, direction rl.Vector3) (DrawableLivingThing, bool) {
	var (
		closestDistance = math.Inf(1)
		closest         DrawableLivingThing
	)
	for _, thing := range city.things {
		if !thing.IsAlive() {
			continue
		}
		thingDistance := rl.Vector3Distance(pos, thing.Pos())
		if thingDistance > float32(closestDistance) {
			continue
		}
		collision := thing.RayCollision(rl.NewRay(pos, direction))
		if collision.Hit {
			closestDistance = float64(thingDistance)
			closest = thing
		}
	}
	return closest, closest != nil
}

func (e *shootingEnemy) Update() {
	if e.health <= 0 {
		return
	}
	e.fireRate.tick()
	playerDistance := rl.Vector3Subtract(city.character.Pos(), e.Pos())
	playerDirection := rl.Vector3Normalize(playerDistance)
	if hitThing, ok := raycast(e.pos, playerDirection); ok {
		if _, ok := hitThing.(*character); ok && e.fireRate.isTimeout() {
			spawnPos := rl.Vector3Add(e.Pos(), rl.Vector3Scale(playerDirection, 2))
			speed := rl.Vector3Scale(playerDirection, 1.5)
			city.AppendParticle(NewMissileProjectile(spawnPos, speed))
			e.fireRate.reset()
		}
	}
	var speed, sideways rl.Vector3
	if rl.Vector3Length(playerDistance) < 50 {
		distance := rl.Vector3Negate(playerDirection)
		speed = rl.Vector3Add(speed, distance)
	}
	{
		sideways = rl.Vector3Transform(playerDirection, rl.MatrixRotateY(90))
		sideways = rl.Vector3Scale(sideways, float32(math.Sin(rl.GetTime()+e.dodgeDelay)))
		speed = rl.Vector3Add(speed, sideways)
	}
	speed = rl.Vector3Normalize(speed)
	e.pos = rl.Vector3Add(e.pos, rl.Vector3Scale(speed, 0.1))
}

func (m *missileProjectile) CauseDamage(int) {
}

func (m *missileProjectile) Update() {
	m.pos = rl.Vector3Add(m.pos, m.speed)
	var (
		closestDistance = math.Inf(1)
		closest         Building
	)
	for _, building := range city.Buildings() {
		if !building.IsAlive() {
			continue
		}
		hitDistance := rl.Vector3Distance(m.Pos(), building.Pos())
		if hitDistance < float32(closestDistance) {
			if building.SphereCollision(m.Pos(), 0.5) {
				closest = building
			}
		}
	}
	if closest != nil {
		closest.CauseDamage(3)
		m.destroyed = true
	}
}

func (m *missileProjectile) Life() int {
	return 999
}

func (m *missileProjectile) IsAlive() bool {
	return !m.destroyed
}

func (m *missileProjectile) Draw() {
	n := rl.Vector3Normalize(m.speed)
	rl.PushMatrix()
	{
		rl.Translatef(m.pos.X, m.pos.Y, m.pos.Z)
		rl.Rotatef(270, n.X, n.Y, n.Z)
		rl.DrawCylinder(rl.Vector3Zero(), 0.1, 0.2, 0.5, 8, rl.White)
	}
	rl.PopMatrix()
}

func (particle *simpleParticle) IsAlive() bool {
	return rl.GetTime() < particle.lifetime
}

func (p *simpleParticle) Update() {
	p.pos = rl.Vector3Add(p.pos, p.speed)
}

func (p *simpleParticle) Pos() rl.Vector3 {
	return p.pos
}

func (particle *simpleParticle) Draw() {
	panic("não implementado")
}

func NewExplosionParticle(direction, pos rl.Vector3) *explosionParticle {
	return &explosionParticle{
		simpleParticle: simpleParticle{
			lifetime: rl.GetTime() + 10 + rand.Float64()*5, speed: direction, pos: pos,
		},
		trailTimer: newTimer(oneSecond * 0.01),
	}
}

func (p *explosionParticle) CauseDamage(int) {}
func (p *explosionParticle) Life() int       { return -1 }

func (p *explosionParticle) Update() {
	timer := p.trailTimer
	timer.tick()
	p.speed = rl.Vector3Add(p.speed, gravity)
	newPos := rl.Vector3Add(p.pos, rl.Vector3Scale(p.speed, rl.GetFrameTime()))
	if newPos.Y <= 0 {
		p.pos.Y = 0
	} else {
		p.pos = newPos
		if timer.isTimeout() {
			// addParticles(NewSmokeTrailParticle(p.pos, p.speed))
			timer.reset()
		}
	}
}

func (p *explosionParticle) Draw() {
	rl.DrawCubeV(p.pos, rl.NewVector3(.1, .1, .1), rl.Gray)
}

// func NewSmokeTrailParticle(pos, speed rl.Vector3) *smokeTrailParticle {
// 	return &smokeTrailParticle{
// 		simpleParticle: simpleParticle{
// 			lifetime: rl.GetTime() + 1,
// 			speed:    rl.Vector3Add(rl.NewVector3(0, .1, 0), rl.Vector3Scale(speed, 0.1)), pos: pos,
// 		},
// 	}
// }

func (p *smokeTrailParticle) Draw() {
	rl.BeginBlendMode(rl.BlendAdditive)
	{
		rl.DrawCubeV(p.pos, rl.NewVector3(.05, .05, .05), rl.Gray)
	}
	rl.EndBlendMode()
}

func (p *bombProjectile) Pos() rl.Vector3 {
	return p.pos
}

func (p *bombProjectile) Draw() {
	rl.DrawSphere(p.pos, 0.5, rl.Gray)
}

func (p *bombProjectile) IsAlive() bool {
	return !p.destroyed
}

func (p *bombProjectile) CauseDamage(int) {
	p.destroyed = true
}

func (p *bombProjectile) Life() int {
	return 1
}

func (p *bombProjectile) Update() {
	p.speed = rl.Vector3Add(p.speed, gravity)
	// FIXME: Voa mais do que deveria em frame rates mais baixos.
	p.pos = rl.Vector3Add(p.pos, rl.Vector3Scale(p.speed, rl.GetFrameTime()))
	if rl.Vector3Length(p.pos) > 1000 {
		p.destroyed = true
	}
	explode := func() {
		p.destroyed = true
		for range 500 {
			direction := rl.NewVector3(rand.Float32()*2-1, 1, rand.Float32()*2-1)
			direction = rl.Vector3Normalize(direction)
			direction = rl.Vector3Scale(direction, 35+rand.Float32()*35)
			city.AppendParticle(NewExplosionParticle(direction, p.pos))
		}
		for _, thing := range city.things {
			if dist := rl.Vector3Distance(p.pos, thing.Pos()); dist < 40 {
				thing.CauseDamage(10)
			}
		}
	}
	if p.pos.Y < 0 {
		explode()
		return
	}
	var (
		closestDistance = math.Inf(1)
		closest         Building
	)
	for _, building := range city.Buildings() {
		if !building.IsAlive() {
			continue
		}
		hitDistance := rl.Vector3Distance(p.pos, building.Pos())
		if hitDistance < float32(closestDistance) {
			if building.SphereCollision(p.pos, 0.5) {
				closest = building
			}
		}
	}
	if closest != nil {
		explode()
		return
	}
}

func drawPlane() {
	rl.DrawPlane(
		rl.NewVector3(16, 0.0, 16),
		rl.NewVector2(2048, 2048),
		rl.NewColor(50, 50, 50, 255),
	)
}

func (s *scene) Draw() {
	character, ok := s.character.(*character)
	if !ok {
		panic(ok)
	}

	rl.BeginDrawing()
	rl.ClearBackground(rl.LightGray)

	rl.BeginMode3D(character.camera)
	{
		for _, thing := range s.things {
			// FIXME:
			if drawable, ok := thing.(Drawable); ok {
				drawable.Draw()
			}
		}
		for _, particle := range s.particles {
			particle.Draw()
		}
		drawPlane()
		// direction = rl.Vector3Subtract(
		//     character.camera.Target, character.camera.Position)
		// aim = rl.Vector3Lerp(direction, aim, 0.95)
		// rl.DrawSphere(rl.Vector3Add(character.camera.Position, aim), 0.1, rl.Red)
	}
	rl.EndMode3D()

	drawHUD()

	rl.DrawLineV(
		rl.NewVector2(WIDTH/2-5, HEIGHT/2-5),
		rl.NewVector2(WIDTH/2+5, HEIGHT/2+5),
		rl.Red,
	)
	rl.DrawLineV(
		rl.NewVector2(WIDTH/2-5, HEIGHT/2+5),
		rl.NewVector2(WIDTH/2+5, HEIGHT/2-5),
		rl.Red,
	)
	rl.DrawFPS(0, HEIGHT-30)

	rl.EndDrawing()
}

func (s *scene) Update() {
	for i := 0; i < len(s.particles); i++ {
		particle := s.particles[i]
		if !particle.IsAlive() {
			city.particles[i] = city.particles[len(city.particles)-1]
			city.particles = city.particles[:len(city.particles)-1]
			i--
			continue
		}
		particle.Update()
	}
	for i := 0; i < len(s.things); i++ {
		thing := s.things[i]
		if alive, ok := thing.(Living); ok && !alive.IsAlive() {
			city.things[i] = city.things[len(city.things)-1]
			city.things = city.things[:len(city.things)-1]
			i--
			continue
		}
		thing.Update()
	}
}

func (c *character) Draw() {

}

func (c *character) Life() int {
	return c.life
}

func (c *character) RayCollision(rl.Ray) rl.RayCollision {
	return rl.RayCollision{}
}

func (c *character) SphereCollision(centerSphere rl.Vector3, radiusSphere float32) bool {
	return false
}

func (c *character) CauseDamage(damage int) {
	c.life -= damage
}

func (c *character) IsAlive() bool {
	return c.life <= 0
}

func (c *character) Pos() rl.Vector3 {
	return c.camera.Position
}

func (c *character) Update() {
	shake := rl.NewVector3(
		randomShake(0.003)*city.healthBar.damageTaken,
		randomShake(0.003)*city.healthBar.damageTaken,
		randomShake(0.003)*city.healthBar.damageTaken,
	)
	c.camera.Target = rl.Vector3Add(c.camera.Target, shake)
	rl.UpdateCamera(&c.camera, rl.CameraFirstPerson)
	// c.laserBeam()
	// c.killAurea()
	c.throwBomb()
}

func (c *character) killAurea() {
	const min = 10
	for _, b := range city.Buildings() {
		if distance := rl.Vector3Distance(c.camera.Position, b.Pos()); distance < min {
			b.CauseDamage(c.damage)
		}
	}
}

func NewProjectile(pos, direction rl.Vector3) *projectile {
	return &projectile{kinecticObject: kinecticObject{object: object{pos: pos}, speed: direction}}
}

func NewBombProjectile(pos, direction rl.Vector3) *bombProjectile {
	return &bombProjectile{projectile: *NewProjectile(pos, direction)}
}

func NewMissileProjectile(pos, direction rl.Vector3) *missileProjectile {
	return &missileProjectile{projectile: *NewProjectile(pos, direction)}
}

func (c *character) throwBomb() {
	if !rl.IsMouseButtonPressed(rl.MouseRightButton) {
		return
	}
	direction := rl.Vector3Normalize(rl.Vector3Subtract(c.camera.Target, c.camera.Position))
	city.AppendParticle(NewBombProjectile(c.camera.Position, rl.Vector3Scale(direction, 130)))
}

func newCharacter() *character {
	return &character{
		camera: rl.Camera3D{
			Position:   rl.NewVector3(4.0, 2.0, 4.0),
			Target:     rl.NewVector3(0.0, 1.8, 0.0),
			Up:         rl.NewVector3(0.0, 1.0, 0.0),
			Fovy:       80.0,
			Projection: rl.CameraPerspective,
		},
		damage: 1,
	}
}

func randomShake(amount float32) float32 {
	return rand.Float32()*amount - amount/2
}

func (hb *healthBar) Draw() {
	const BARWIDTH = (WIDTH - MARGIN*2)

	currentLife := 0
	for _, thing := range city.things {
		if building, ok := thing.(*building); ok {
			currentLife += building.Life()
		}
	}
	maxLife := buildingsHealth * totalBuildings
	position := rl.NewVector2(MARGIN, 10)
	barWidth := BARWIDTH * currentLife / maxLife

	size := rl.NewVector2(float32(barWidth), 10)

	hb.damageTaken += float32(hb.life - currentLife)

	damageTakenBar := size
	damageTakenBar.X = BARWIDTH *
		(float32(currentLife) + hb.damageTaken) / float32(maxLife)

	shake := rl.NewVector2(
		randomShake(0.4)*hb.damageTaken,
		randomShake(0.4)*hb.damageTaken,
	)
	position = rl.Vector2Add(position, shake)

	rl.DrawRectangleV(position, damageTakenBar, rl.Orange)
	rl.DrawRectangleV(position, size, rl.Red)

	hb.lastUpdate = rl.GetTime()
	hb.life = currentLife
	hb.damageTaken *= 0.95
}

func newHealthBar(buildings []Building) *healthBar {
	return &healthBar{life: buildingsHealth * len(buildings)}
}

func (b *building) Update() {}

func (b *building) SphereCollision(centerSphere rl.Vector3, radiusSphere float32) bool {
	return rl.CheckCollisionBoxSphere(b.boundingBox, centerSphere, radiusSphere)
}

func (b *building) RayCollision(ray rl.Ray) rl.RayCollision {
	return rl.GetRayCollisionBox(ray, b.boundingBox)
}

func (b *building) Life() int {
	return b.life
}

func (b *building) Animation() animationFunc {
	return b.animate
}

func (b *building) Animate() animationOver {
	return b.animate()
}

func (b *building) SetAnimation(f animationFunc) {
	b.animate = f
}

func (b *building) CauseDamage(damage int) {
	if b.animate != nil || b.life <= 0 {
		return
	}
	b.animate = shakeBuilding(b)
	b.life -= damage
}

func (b *building) IsAlive() bool {
	return b.life > 0 || b.animate != nil
}

func newBuilding(x, z float32) *building {
	color := rl.NewColor(
		uint8(rl.GetRandomValue(0, 180)),
		uint8(rl.GetRandomValue(0, 180)),
		uint8(rl.GetRandomValue(0, 180)),
		255,
	)
	pos := rl.NewVector3(x*buildingSpacing, 0, z*buildingSpacing)
	size := rl.NewVector3(
		buildingSize,
		float32(rl.GetRandomValue(1, maxBuildingHeight)),
		buildingSize,
	)
	min := rl.NewVector3(
		pos.X-buildingSize/2,
		0,
		pos.Z-buildingSize/2,
	)
	max := rl.NewVector3(
		pos.X+buildingSize/2,
		size.Y/2,
		pos.Z+buildingSize/2,
	)
	return &building{
		color:       color,
		life:        buildingsHealth,
		object:      object{pos: pos},
		size:        size,
		boundingBox: rl.NewBoundingBox(min, max),
	}
}

func drawWireframe(building building) {
	increasedSize := rl.Vector3Scale(building.size, 1.05)
	invertedColor := building.color
	invertedColor.R += 127
	invertedColor.G += 127
	invertedColor.B += 127
	rl.DrawCubeWiresV(
		building.pos,
		increasedSize,
		invertedColor,
	)
}

func shakeEnemy(enemy *shootingEnemy) animationFunc {
	duration := newTimer(0.7)
	return func() animationOver {
		if 0 == 0 {
			if !enemy.IsAlive() {
				enemy.color = rl.NewColor(255, 0, 0, 255)
			} else {
				enemy.color = rl.RayWhite
			}
		}
		shake := rl.NewVector3(
			rand.Float32()*.2-.1,
			rand.Float32()*.1-.05,
			rand.Float32()*.2-.1,
		)
		rl.DrawSphere(rl.Vector3Add(enemy.Pos(), shake), 1, rl.Red)
		return animationOver(duration.ttr())
	}
}

func shakeBuilding(b *building) animationFunc {
	duration := newTimer(0.7)
	t := newTimer(0.08)
	return func() animationOver {
		building := *b
		if t.ttr() {
			if b.life == 0 {
				building.color = rl.NewColor(255, 0, 0, 255)
			} else {
				building.color = rl.RayWhite
			}
		}
		drawWireframe(building)
		shake := rl.NewVector3(
			rand.Float32()*.2-.1,
			rand.Float32()*.1-.05,
			rand.Float32()*.2-.1,
		)
		shake = rl.Vector3Scale(shake, float32(math.Sin(rl.GetTime())+1)/3)
		rl.DrawCubeV(
			rl.Vector3Add(building.pos, shake),
			building.size,
			building.color,
		)
		return animationOver(duration.ttr())
	}
}

func (b *building) Draw() {
	hasAnimation := b.Animation() != nil
	if b.Life() <= 0 && !hasAnimation {
		return
	}
	if hasAnimation {
		if over := b.Animate(); over {
			b.SetAnimation(nil)
		}
		return
	}
	drawWireframe(*b)
	rl.DrawCubeV(b.pos, b.size, b.color)
}

func (c *character) laserBeam() {
	if !rl.IsMouseButtonDown(rl.MouseLeftButton) {
		return
	}
	ray := rl.Ray{
		Position:  c.camera.Position,
		Direction: rl.Vector3Subtract(c.camera.Target, c.camera.Position),
	}
	closestDistance := math.Inf(1)
	var closest Building
	for _, building := range city.Buildings() {
		if !building.IsAlive() {
			continue
		}
		playerDistance := rl.Vector3Distance(c.camera.Position, building.Pos())
		if playerDistance < float32(closestDistance) {
			collision := building.RayCollision(ray)
			if collision.Hit {
				closestDistance = float64(playerDistance)
				closest = building
			}
		}
	}
	if closest != nil {
		closest.CauseDamage(c.damage)
	}
}

func newBuildings() []Building {
	var buildings []Building
	mb := int(math.Sqrt(totalBuildings))
	for i := 0; i < mb; i++ {
		for j := 0; j < mb; j++ {
			buildings = append(buildings, newBuilding(float32(i)-10, float32(j)-10))
		}
	}
	return buildings
}

func newBuildingBlocks() []Building {
	var buildings []Building
	for i := 0; i < blocksNumber; i++ {
		for j := 0; j < blocksNumber; j++ {
			for k := 0; k < buildsPerBlock; k++ {
				for l := 0; l < buildsPerBlock; l++ {
					buildings = append(buildings, newBuilding(float32(i), float32(j)))
				}
			}
		}
	}
	return buildings
}

func drawHUD() {
	city.healthBar.Draw()
	rl.DrawText(
		fmt.Sprintf("buildings destroyed: %d", 1024-len(city.Buildings())), MARGIN, MARGIN, 20, rl.White,
	)
	rl.DrawText(fmt.Sprintf("frame time: %f", rl.GetFrameTime()), MARGIN, MARGIN+MARGIN, 20, rl.White)
}

func spawnEnemies() []DrawableLivingThing {
	var ret []DrawableLivingThing
	for range 20 {
		e := NewShootingEnemy(rl.NewVector3(rand.Float32()*400-200, 2, rand.Float32()*400-200), 6)
		ret = append(ret, e)
	}
	return ret
}

func main() {
	rl.SetConfigFlags(rl.FlagMsaa4xHint)
	rl.InitWindow(WIDTH, HEIGHT, "raylib [core] example - 3d camera first person")
	rl.SetTargetFPS(120)
	rl.HideCursor()
	rl.DisableCursor()
	rl.SetMousePosition(WIDTH/2, HEIGHT/2)

	character := newCharacter()
	buildings := newBuildings()
	healthBar := newHealthBar(buildings)

	city = &scene{healthBar: healthBar, character: character}

	// Linguagem burra
	var b []DrawableLivingThing = make([]DrawableLivingThing, len(buildings))
	for i, bu := range buildings {
		b[i] = bu
	}

	city.AppendThing(spawnEnemies()...)
	city.AppendThing(b...)
	city.AppendThing(character)

	for !rl.WindowShouldClose() {
		city.Update()
		city.Draw()
	}

	rl.CloseWindow()
}