survive/gameelement/canvas.go

package gameelement

import (
	"fmt"
	"image/color"
	"math"
	"math/rand/v2"
	"mover/assets"
	"mover/elements"
	"mover/fonts"
	"mover/gamedata"

	"github.com/hajimehoshi/ebiten/v2"
	"github.com/hajimehoshi/ebiten/v2/text"
	"github.com/hajimehoshi/ebiten/v2/vector"
)

type Canvas struct {
	Sprite            *ebiten.Image
	collisionMask     *ebiten.Image
	projectileMask    *ebiten.Image
	heroCollisionMask *ebiten.Image
	heroCollisionCpy  *ebiten.Image

	eventmap map[gamedata.GameEvent]func()

	initialized bool
	lastInputs  gamedata.GameInputs
	runtime     float64
	counter     int
	score       int
	hero        *elements.Hero
	charge      *elements.Explosion
	enemies     []elements.Enemies
	projectiles []*elements.Projectile
	gameover    bool
}

func NewCanvas(a gamedata.Area) *Canvas {
	c := &Canvas{
		Sprite:            ebiten.NewImage(a.Width, a.Height),
		projectileMask:    ebiten.NewImage(a.Width, a.Height),
		collisionMask:     ebiten.NewImage(a.Width, a.Height),
		heroCollisionMask: ebiten.NewImage(46, 46),
		heroCollisionCpy:  ebiten.NewImage(46, 46),
		hero:              elements.NewHero(),
		charge:            elements.NewExplosion(),
		initialized:       false,
		gameover:          false,
		score:             0,
		runtime:           0.,
	}
	c.eventmap = make(map[gamedata.GameEvent]func())
	return c
}

func (c *Canvas) SetInputs(gi gamedata.GameInputs) {
	c.lastInputs = gi
}

func (c *Canvas) Update() error {
	if !c.initialized {
		c.Initialize()
	} else {
		//update positions()
		//hero first
		c.UpdateHero()
		c.UpdateProjectiles()
		c.UpdateCharge()
		c.UpdateEnemies()
		c.CleanupTargets()

	}
	c.counter++
	return nil
}

func (c *Canvas) Draw(drawimg *ebiten.Image) {
	c.Sprite.Clear()
	c.projectileMask.Clear()

	//vector.DrawFilledCircle(c.Sprite, float32(c.hero.Pos.X), float32(c.hero.Pos.Y), 100, color.White, true)

	c.hero.Draw()
	op := &ebiten.DrawImageOptions{}
	op.GeoM.Translate(c.hero.Pos.X-48/2, c.hero.Pos.Y-48/2)
	c.Sprite.DrawImage(c.hero.Sprite, op)

	if !c.gameover {
		op.GeoM.Reset()
		op.GeoM.Translate(0, -16)
		op.GeoM.Rotate(c.lastInputs.ShotAngle)
		op.GeoM.Translate(c.hero.Pos.X, c.hero.Pos.Y)
		c.Sprite.DrawImage(assets.ImageBank[assets.Weapon], op)
	}

	for _, e := range c.enemies {
		e.Draw()
		op := &ebiten.DrawImageOptions{}
		op.GeoM.Translate(e.GetPosition().X-46/2, e.GetPosition().Y-46/2)
		c.Sprite.DrawImage(e.GetSprite(), op)
	}

	for _, p := range c.projectiles {
		//drawimg.DrawImage()
		vector.DrawFilledCircle(c.projectileMask, float32(p.Pos.X), float32(p.Pos.Y), 3, color.White, true)
	}

	c.Sprite.DrawImage(c.projectileMask, nil)

	vector.StrokeCircle(c.Sprite, float32(c.charge.Origin.X), float32(c.charge.Origin.Y), float32(c.charge.Radius), 3, color.White, true)

	if !c.gameover {
		c.runtime = float64(c.counter) / 60.
	}
	s := fmt.Sprintf("%02.3f", c.runtime)
	if !c.gameover {
		text.Draw(c.Sprite, "TIME: "+s, fonts.SurviveFont.Arcade, 640/2-250, 25, color.White)
		text.Draw(c.Sprite, fmt.Sprintf("SCORE: %d", c.score*10), fonts.SurviveFont.Arcade, 640/2+100, 25, color.White)
	} else {
		if (c.counter/30)%2 == 0 {
			text.Draw(c.Sprite, "TIME: "+s, fonts.SurviveFont.Arcade, 640/2-250, 25, color.White)
			text.Draw(c.Sprite, fmt.Sprintf("SCORE: %d", c.score*10), fonts.SurviveFont.Arcade, 640/2+100, 25, color.White)
		}

		text.Draw(c.Sprite, "PRESS START TO TRY AGAIN", fonts.SurviveFont.Arcade, 640/2-150, 480/2, color.White)
	}

	//op := &ebiten.DrawImageOptions{}
	op.GeoM.Reset()
	drawimg.DrawImage(c.Sprite, op)
}

func (c *Canvas) Initialize() {

	c.InitializeHero()
	c.enemies = c.enemies[:0]
	c.gameover = false
	c.initialized = true
	c.score = 0
	c.counter = 0
	c.runtime = 0.

	//temporary
	c.hero.Action = elements.HeroActionDefault
}

func (c *Canvas) UpdateHero() {
	c.hero.Update()
	if !c.gameover {
		c.UpdateHeroPosition()
		c.ComputeHeroCollisions()
		c.AddProjectiles()
	}
}

func (c *Canvas) UpdateHeroPosition() {
	if c.lastInputs.XAxis >= 0.15 || c.lastInputs.XAxis <= -0.15 {
		c.hero.Left = c.lastInputs.XAxis < 0
		c.hero.Pos.X += c.lastInputs.XAxis * 5
	}

	if c.lastInputs.YAxis >= 0.15 || c.lastInputs.YAxis <= -0.15 {
		c.hero.Pos.Y += c.lastInputs.YAxis * 5
	}
}

func (c *Canvas) ComputeHeroCollisions() {
	for _, e := range c.enemies {
		//compute collision with hero
		if c.hero.Pos.X >= e.GetPosition().X-46/2 && c.hero.Pos.X <= e.GetPosition().X+46/2 &&
			c.hero.Pos.Y >= e.GetPosition().Y-46/2 && c.hero.Pos.Y <= e.GetPosition().Y+46/2 &&
			e.GetEnemyState() < gamedata.EnemyStateDying {

			// 			target.Action < elements.MoverActionDying && g.hero.Action < elements.HeroActionDying {

			c.heroCollisionMask.Clear()
			c.heroCollisionMask.DrawImage(c.hero.Sprite, nil)

			op := &ebiten.DrawImageOptions{}
			op.GeoM.Reset()
			op.Blend = ebiten.BlendSourceIn
			op.GeoM.Translate((c.hero.Pos.X-e.GetPosition().X)-float64(e.GetSprite().Bounds().Dx())/2, (c.hero.Pos.Y-e.GetPosition().Y)-float64(e.GetSprite().Bounds().Dy())/2)
			c.heroCollisionMask.DrawImage(e.GetSprite(), op)

			if c.HasCollided(c.heroCollisionMask, 46*46*4) {
				c.hero.SetHit()
				c.gameover = true

				if c.eventmap[gamedata.GameEventPlayerDeath] != nil {
					c.eventmap[gamedata.GameEventPlayerDeath]()
				}
			}
		}
	}
}

func (c *Canvas) AddProjectiles() {

	//add new projectiles
	if c.lastInputs.Shot && c.counter%14 == 0 {
		loc := gamedata.Coordinates{
			X: c.hero.Pos.X,
			Y: c.hero.Pos.Y,
		}
		angle := c.lastInputs.ShotAngle
		velocity := 5.
		c.projectiles = append(c.projectiles, elements.NewProjectile(loc, angle, velocity))

		if c.hero.Upgrade {
			c.projectiles = append(c.projectiles, elements.NewProjectile(loc, angle+math.Pi, velocity))
		}

		if c.eventmap[gamedata.GameEventNewShot] != nil {
			c.eventmap[gamedata.GameEventNewShot]()
		}
	}

}

func (c *Canvas) InitializeHero() {
	//recenter the hero
	pos := gamedata.Coordinates{
		X: float64(c.Sprite.Bounds().Dx() / 2),
		Y: float64(c.Sprite.Bounds().Dy() / 2),
	}
	c.hero.SetOrigin(pos)
}

func (c *Canvas) UpdateProjectiles() {
	i := 0
	for _, p := range c.projectiles {
		p.Update()

		projectilevalid := true

		if p.Pos.X < -640/2 || p.Pos.X > 1.5*640 || p.Pos.Y < -480/2 || p.Pos.Y > 1.5*480 {
			projectilevalid = false
		}

		for _, e := range c.enemies {
			if p.Pos.X >= e.GetPosition().X-48/2 && p.Pos.X <= e.GetPosition().X+48/2 &&
				p.Pos.Y >= e.GetPosition().Y-48/2 && p.Pos.Y <= e.GetPosition().Y+48/2 &&
				e.IsToggled() && e.GetEnemyState() < gamedata.EnemyStateDying {
				c.collisionMask.Clear()
				c.collisionMask.DrawImage(c.projectileMask, nil)

				op := &ebiten.DrawImageOptions{}
				op.GeoM.Reset()
				op.Blend = ebiten.BlendSourceIn
				op.GeoM.Translate(e.GetPosition().X-float64(e.GetSprite().Bounds().Dx())/2, e.GetPosition().Y-float64(e.GetSprite().Bounds().Dy())/2)
				c.collisionMask.DrawImage(e.GetSprite(), op)

				if c.HasCollided(c.collisionMask, 640*480*4) {
					//fmt.Println("pixel collision")
					//delete(g.projectiles, k)
					projectilevalid = false
					//target.ToggleColor()
					e.SetHit()
					//target.SetOrigin(gamedata.Coordinates{X: rand.Float64() * 640, Y: rand.Float64() * 480})
					//target.Hit = true

					/*player := audioContext.NewPlayerFromBytes(assets.TargetHit)
					player.Play()*/
					if c.eventmap[gamedata.GameEventTargetHit] != nil {
						c.eventmap[gamedata.GameEventTargetHit]()
					}
				}
			}
		}

		if projectilevalid {
			c.projectiles[i] = p
			i++
		}
	}

	for j := i; j < len(c.projectiles); j++ {
		c.projectiles[j] = nil
	}
	c.projectiles = c.projectiles[:i]

}

func (c *Canvas) UpdateCharge() {

	if c.lastInputs.Charge && !c.charge.Active && !c.gameover {
		c.charge.SetOrigin(c.hero.Pos)
		c.charge.Reset()
		c.charge.ToggleActivate()

		if c.eventmap[gamedata.GameEventCharge] != nil {
			c.eventmap[gamedata.GameEventCharge]()
		}
	}

	c.charge.Update()
	if c.charge.Active {
		if c.charge.Radius > math.Sqrt(640*640+480*480) {
			c.charge.ToggleActivate()
			c.charge.Reset()
			c.ResetTargetTouches()
		}

		for _, e := range c.enemies {
			dx := e.GetPosition().X - c.hero.Pos.X
			dy := e.GetPosition().Y - c.hero.Pos.Y
			r := math.Sqrt(dx*dx + dy*dy)

			if r >= c.charge.Radius-5 && r <= c.charge.Radius+5 &&
				!e.IsTouched() && e.GetEnemyState() <= gamedata.EnemyStateHit {
				e.SetToggle()
				e.SetTouched()
			}
		}
	}
}

func (c *Canvas) ResetTargetTouches() {
	for _, e := range c.enemies {
		e.ClearTouched()
	}
}

func (c *Canvas) UpdateEnemies() {
	//update existing enemies
	for _, e := range c.enemies {
		if !c.gameover {
			e.SetTarget(c.hero.Pos)
		} else {
			e.SetTarget(e.GetPosition())
		}

		e.Update()
	}
	if !c.gameover {
		//spawn new enemies
		f := 40000 / (c.counter + 1)

		if c.counter%f == 0 {
			newenemy := elements.NewFlyEye()

			x0 := rand.Float64() * 640
			y0 := rand.Float64() * 480
			quadrant := rand.IntN(3)

			switch quadrant {
			case 0:
				newenemy.SetPosition(gamedata.Coordinates{X: x0, Y: -48})
			case 1:
				newenemy.SetPosition(gamedata.Coordinates{X: x0, Y: 480 + 48})
			case 2:
				newenemy.SetPosition(gamedata.Coordinates{X: -48, Y: y0})
			case 3:
				newenemy.SetPosition(gamedata.Coordinates{X: 640 + x0, Y: y0})
			}

			newenemy.SetTarget(c.hero.Pos)

			c.enemies = append(c.enemies, newenemy)
		}
	}
}

func (c *Canvas) HasCollided(mask *ebiten.Image, size int) bool {
	var result bool = false
	var pixels []byte = make([]byte, size)
	mask.ReadPixels(pixels)
	for i := 0; i < len(pixels); i = i + 4 {
		if pixels[i+3] != 0 {
			result = true
			break
		}
	}
	return result
}

func (c *Canvas) RegisterEvents(e gamedata.GameEvent, f func()) {
	c.eventmap[e] = f
}

func (c *Canvas) CleanupTargets() {
	// remove dead targets by iterating over all targets
	i := 0
	for _, e := range c.enemies {
		//moving valid targets to the front of the slice
		if e.GetEnemyState() < elements.MoverActionDead {
			c.enemies[i] = e
			i++
		}
	}

	//then culling the last elements of the slice, and conveniently we can update
	//our base score with the number of elements removed (bonuses calculated elsewhere)
	if len(c.enemies)-i > 0 {
		c.score += len(c.enemies) - i
	}

	for j := i; j < len(c.enemies); j++ {
		c.enemies[j] = nil
	}
	c.enemies = c.enemies[:i]
}