pico-go particle effect https://github.com/telecoda/pico-go

pico-go-particles.go

package code

import (
	"math"
	"math/rand"
	"time"

	"github.com/telecoda/pico-go/console"
)

var colors = []console.Color{
	console.PICO8_BLUE,
	console.PICO8_GREEN,
	console.PICO8_INDIGO,
	console.PICO8_ORANGE,
	console.PICO8_PEACH,
	console.PICO8_PINK,
}

type cartridge struct {
	*console.BaseCartridge

	particles []*particle
	last      time.Time
}

func NewCart() console.Cartridge {
	return &cartridge{
		BaseCartridge: console.NewBaseCart(),
	}
}

func (c *cartridge) Init() {
	c.particles = []*particle{}
	c.last = time.Now()

	explode := func(x, y int) {
		n := 4 + rand.Intn(15)

		for i := 0; i < 1+rand.Intn(3); i++ {
			color := colors[rand.Intn(len(colors))]

			for i := 0; i < n; i++ {
				angle := 90.0 + rand.Float64()*180.0*flip()
				speed := (1.1 * float64(n)) + (float64(i) * rand.Float64())
				life := 0.5 + (1.3 * rand.Float64())

				c.particles = append(c.particles,
					newParticle(float64(x), float64(y), angle, speed, life, color),
				)
			}
		}
	}

	go func() {
		for {
			time.Sleep(300 * time.Millisecond)

			explode(
				rand.Intn(c.GetConfig().ConsoleWidth),
				rand.Intn(c.GetConfig().ConsoleHeight),
			)
		}
	}()
}

func (c *cartridge) Update() {
	dt := time.Since(c.last).Seconds()
	c.last = time.Now()

	aliveParticles := []*particle{}

	for _, p := range c.particles {
		p.update(dt)

		if p.life > 0 {
			aliveParticles = append(aliveParticles, p)
		}
	}

	c.particles = aliveParticles
}

func (c *cartridge) Render() {
	c.ClsWithColor(console.PICO8_BLACK)

	for _, p := range c.particles {
		c.PSetWithColor(int(p.position.X), int(p.position.Y), p.color)
	}
}

type vec struct {
	X, Y float64
}

type particle struct {
	angle    float64
	speed    float64
	position vec
	velocity vec
	color    console.Color
	life     float64
}

func newParticle(x, y, angle, speed, life float64, c console.Color) *particle {
	angleInRadians := angle * math.Pi / 180

	return &particle{
		angle:    angle,
		speed:    speed,
		position: vec{x, y},
		velocity: vec{
			X: speed * math.Cos(angleInRadians),
			Y: -speed * math.Sin(angleInRadians),
		},
		life:  life,
		color: c,
	}
}

func (p *particle) update(dt float64) {
	p.life -= dt

	if p.life > 0 {
		p.position.X += p.velocity.X * dt
		p.position.Y += p.velocity.Y * dt

		if p.life < 0.2 {
			p.color = console.PICO8_DARK_GRAY
		}
	}
}

func flip() float64 {
	if rand.Float64() > 0.5 {
		return 1.0
	}

	return -1.0
}

The current version of telecoda/pico-go@18b1200 correctly imports the go-sdl2 packages 👍