105 lines
2.1 KiB
Go
105 lines
2.1 KiB
Go
// For more tutorials: https://blog.learngoprogramming.com
|
|
//
|
|
// Copyright © 2018 Inanc Gumus
|
|
// Learn Go Programming Course
|
|
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
|
|
//
|
|
|
|
package main
|
|
|
|
import (
|
|
"fmt"
|
|
"time"
|
|
|
|
"github.com/inancgumus/screen"
|
|
"github.com/mattn/go-runewidth"
|
|
)
|
|
|
|
func main() {
|
|
const (
|
|
cellEmpty = ' '
|
|
cellBall = '⚾'
|
|
|
|
maxFrames = 1200
|
|
speed = time.Second / 20
|
|
)
|
|
|
|
var (
|
|
px, py int // ball position
|
|
ppx, ppy int // previous ball position
|
|
vx, vy = 5, 2 // velocities
|
|
|
|
cell rune // current cell (for caching)
|
|
)
|
|
|
|
// you can get the width and height using the screen package easily:
|
|
width, height := screen.Size()
|
|
|
|
// get the rune width of the ball emoji
|
|
ballWidth := runewidth.RuneWidth(cellBall)
|
|
|
|
// adjust the width and height
|
|
width /= ballWidth
|
|
height-- // there is a 1 pixel border in my terminal
|
|
|
|
// create a single-dimensional board
|
|
board := make([]bool, width*height)
|
|
|
|
// create a drawing buffer
|
|
buf := make([]rune, 0, width*height)
|
|
|
|
// clear the screen once
|
|
screen.Clear()
|
|
|
|
for i := 0; i < maxFrames; i++ {
|
|
// calculate the next ball position
|
|
px += vx
|
|
py += vy
|
|
|
|
// when the ball hits a border reverse its direction
|
|
if px <= 0 || px >= width-1 {
|
|
vx *= -1
|
|
}
|
|
if py <= 0 || py >= height-1 {
|
|
vy *= -1
|
|
}
|
|
|
|
// check whether the ball goes beyond the borders
|
|
if px < width && py < height {
|
|
// calculate the new and the previous ball positions
|
|
pos := py*width + px
|
|
ppos := ppy*width + ppx
|
|
|
|
// remove the previous ball and put the new ball
|
|
board[pos], board[ppos] = true, false
|
|
|
|
// save the previous positions
|
|
ppx, ppy = px, py
|
|
}
|
|
|
|
// rewind the buffer (allow appending from the beginning)
|
|
buf = buf[:0]
|
|
|
|
// draw the board into the buffer
|
|
for y := 0; y < height; y++ {
|
|
for x := 0; x < width; x++ {
|
|
cell = cellEmpty
|
|
|
|
if board[y*width+x] {
|
|
cell = cellBall
|
|
}
|
|
|
|
buf = append(buf, cell, ' ')
|
|
}
|
|
buf = append(buf, '\n')
|
|
}
|
|
|
|
// print the buffer
|
|
screen.MoveTopLeft()
|
|
fmt.Print(string(buf))
|
|
|
|
// slow down the animation
|
|
time.Sleep(speed)
|
|
}
|
|
}
|