blinkTrail.go

package main

import (
	"image"

	"github.com/hajimehoshi/ebiten"
)

// BlinkTrail the trail when the player blinks
type BlinkTrail struct {
	speed    float64
	speedMax float64

	sections []BlinkTrailSection
}

// BlinkTrailSection is the actual animated section of the trail
type BlinkTrailSection struct {
	position Vec2f

	spritesheet Spritesheet
	animation   *Animation

	timeToLive int // cya loser lol
	delete     bool
	direction  Direction

	image *ebiten.Image
}

// BlinkTrail
func createBlinkTrail(speed float64) BlinkTrail {
	return BlinkTrail{
		speed:    speed,
		speedMax: speed,

		sections: []BlinkTrailSection{},
	}
}

func (b *BlinkTrail) render(screen *ebiten.Image) {
	for _, s := range b.sections {
		s.render(screen)
	}
}

func (b *BlinkTrail) update() {
	for i := 0; i < len(b.sections); i++ {
		b.sections[i].update()
	}
}

func (b *BlinkTrail) spawnUpdate(position Vec2f, direction Direction) {
	// Add new section every few ticks
	if b.speed >= 0 {
		b.speed--
	} else {
		t := createBlinkTrailSection(position, direction)
		b.sections = append(b.sections, t)
		b.speed = b.speedMax
		t.animation.startBackwards()
	}
}

// BlinkTrailSection

func createBlinkTrailSection(position Vec2f, direction Direction) BlinkTrailSection {
	image := iplayerSpritesheet
	blinkSpritesheet := createSpritesheet(newVec2i(102, 153), newVec2i(145, 171), 3, image)
	animation := createAnimation(blinkSpritesheet, image)

	return BlinkTrailSection{
		position: position,

		spritesheet: blinkSpritesheet,
		animation:   &animation,
		direction:   direction,

		timeToLive: 21,

		image: image,
	}
}

func (b *BlinkTrailSection) render(screen *ebiten.Image) {
	op := &ebiten.DrawImageOptions{}
	op.GeoM.Translate(0, 0)
	// If the player is facing left, then flip the sprite 180 [-x, y]
	if b.direction == Left || b.direction == DownLeft || b.direction == UpLeft {
		op.GeoM.Scale(-1, 1)
		b.position.x += float64(b.spritesheet.sprites[0].size.x)
	}
	op.GeoM.Translate(b.position.x, b.position.y)
	op.Filter = ebiten.FilterNearest // Maybe fix rotation grossness?
	subImageRect := image.Rect(
		b.spritesheet.sprites[b.animation.currentFrame].startPosition.x,
		b.spritesheet.sprites[b.animation.currentFrame].startPosition.y,
		b.spritesheet.sprites[b.animation.currentFrame].endPosition.x,
		b.spritesheet.sprites[b.animation.currentFrame].endPosition.y,
	)
	screen.DrawImage(b.image.SubImage(subImageRect).(*ebiten.Image), op)
}

func (b *BlinkTrailSection) update() {
	if b.timeToLive <= 0 {
		b.delete = true // Delete the boy
	}
	b.timeToLive--
	b.animation.update(1.5)
}