advert.go

package main

import (
	"fmt"
	"github.com/faiface/pixel"
	"github.com/faiface/pixel/text"
	"golang.org/x/image/font/basicfont"
	"math/rand"
	"time"
)

const advertMessageSpacing = "     "
const textSpeed = 5

var advertMessages = []string{
	"Welcome to Beat Phaser. Try not to die, won't you?",
	"Boogie",
	"Y'know so much of the music we hear today is pre-programmed electronic disco, we never get a chance to hear master blues men practicing their craft anymore.",
	"By the year 2006, the music known today as the blues will exist only in the classical records department of your local public library.",
	"You're gonna carry that weight.",
	"Eat, Sleep, Buy Stuff, Dance.",
	"Hello World!",
	"Ship it!",
	"<3 <3 <3",
}

type advert struct {
	pos   pixel.Vec
	atlas *text.Atlas

	i        float64
	maxWidth int

	text      string
	shownText string

	tick <-chan time.Time
}

func (a *advert) init() {
	a.atlas = text.NewAtlas(
		basicfont.Face7x13,
		text.ASCII,
	)

	for i := range advertMessages {
		if len(advertMessages[i]) < a.maxWidth {
			for j := len(advertMessages[i]); j < a.maxWidth; j++ {
				advertMessages[i] += " "
			}
		}
	}

	a.text = advertMessages[0] + advertMessageSpacing
	a.tick = time.Tick(time.Second * 20)
}

func (a *advert) pickRandomMessage() {
	r := rand.Intn(len(advertMessages))

	a.text = advertMessages[r] + advertMessageSpacing
	a.shownText = ""
	a.i = 0
}

func (a *advert) update(dt float64) {
	i := int(a.i)

	if i == len(a.text)-1 {
		select {
		case <-a.tick:
			a.pickRandomMessage()
			return
		default:

		}
	}

	if i+a.maxWidth < len(a.text) {
		a.shownText = a.text[i : i+a.maxWidth]

		a.i += dt * textSpeed
	} else if i < len(a.text) {
		a.shownText = a.text[i:]

		a.i += dt * textSpeed
	} else {
		a.i = 0
	}

	j := 0

	for len(a.shownText) < a.maxWidth && j < len(a.text) {
		a.shownText += string(a.text[j])
		j++
	}
}

func (a *advert) draw(t pixel.Target) {
	tx := text.New(a.pos, a.atlas)
	tx.Color = pixel.RGB(235.0/255.0, 35.0/255.0, 208.0/255.0)

	_, err := fmt.Fprintf(tx, a.shownText)

	if err != nil {
		panic(err)
	}

	tx.Draw(t, pixel.IM)
}