fix: bouncing ball exercises
This commit is contained in:
Inanc Gumus
182
18-project-bouncing-ball/exercises/02-width-and-height/main.go
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182
18-project-bouncing-ball/exercises/02-width-and-height/main.go
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// For more tutorials: https://blog.learngoprogramming.com
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//
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// Copyright © 2018 Inanc Gumus
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// Learn Go Programming Course
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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//
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package main
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import (
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"fmt"
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"time"
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"github.com/inancgumus/screen"
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)
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// ---------------------------------------------------------
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// EXERCISE: Adjust the width and height automatically
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//
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// In this exercise, your goal is simple:
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//
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// Instead of setting the width and height manually,
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// you need to get the width and height of the terminal
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// screen from your operating system.
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//
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// Don't worry, it is easier than it sounds. You just
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// need to read a few documentation and install a
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// Go package.
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//
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// 1. Go here: https://godoc.org/golang.org/x/crypto/ssh/terminal
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//
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// Download the package:
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// go get -u golang.org/x/crypto/ssh/terminal
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//
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// 2. Find the function that gives you the width and height
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// of the terminal.
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//
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// 3. Call that function from your program and get the
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// width and height.
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//
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// 4. When an error occurs while retrieving the width
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// and height, report it.
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//
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// 5. Set the width and height of the board.
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//
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// 6. After solving the above steps, update your program
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// to use my screen package instead. It offers an
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// easier way to get the width and height of a
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// terminal.
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//
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// go get -u https://github.com/inancgumus/screen
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//
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//
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// BONUS
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//
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// 1. When you set the width, you may see that the ball
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// goes beyond the left and right borders. This happens
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// because the ball emoji spans to multiple console
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// columns (or cells). Ordinary characters have a
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// single column.
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//
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// 1. Get the width of the ball emoji using a function
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// from the following package:
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//
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// go get -u github.com/mattn/go-runewidth
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//
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// 2. Divide the width using the rune width of the
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// ball emoji.
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//
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// 2. Your terminal may have borders, so reduce the
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// height by taking into account the height of
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// your terminal borders.
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//
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//
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// EXPECTED OUTPUT
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//
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// When you run the program, the ball should start
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// animating across the total width and height of your
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// terminal screen dynamically.
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//
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// Currently you set width and height manually, so it
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// wasn't matter whether your terminal was bigger or
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// smaller, but now it will be!
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//
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//
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// HINT
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//
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// Please take a look at this if you get stuck.
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//
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// You need to pass the Standard Out file handler
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// to the function that returns you the dimensions.
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//
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// Check out my screen package to find out how I'm
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// passing the Standard Out file handler.
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//
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// https://github.com/inancgumus/screen/blob/master/dimensions.go
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//
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// ---------------------------------------------------------
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func main() {
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const (
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width = 50
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height = 10
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cellEmpty = ' '
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cellBall = '⚾'
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maxFrames = 1200
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speed = time.Second / 20
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// drawing buffer length
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//
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// *2 for extra spaces
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// +1 for newlines
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bufLen = (width*2 + 1) * height
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)
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var (
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px, py int // ball position
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vx, vy = 1, 1 // velocities
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cell rune // current cell (for caching)
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)
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// create the board
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board := make([][]bool, width)
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for column := range board {
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board[column] = make([]bool, height)
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}
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// create a drawing buffer
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buf := make([]rune, 0, bufLen)
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// clear the screen once
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screen.Clear()
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for i := 0; i < maxFrames; i++ {
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// calculate the next ball position
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px += vx
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py += vy
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// when the ball hits a border reverse its direction
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if px <= 0 || px >= width-1 {
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vx *= -1
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}
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if py <= 0 || py >= height-1 {
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vy *= -1
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}
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// remove the previous ball
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for y := range board[0] {
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for x := range board {
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board[x][y] = false
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}
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}
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// put the new ball
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board[px][py] = true
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// rewind the buffer (allow appending from the beginning)
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buf = buf[:0]
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// draw the board into the buffer
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for y := range board[0] {
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for x := range board {
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cell = cellEmpty
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if board[x][y] {
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cell = cellBall
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}
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buf = append(buf, cell, ' ')
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}
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buf = append(buf, '\n')
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}
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// print the buffer
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screen.MoveTopLeft()
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fmt.Print(string(buf))
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// slow down the animation
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time.Sleep(speed)
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}
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}
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@ -0,0 +1,116 @@
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// For more tutorials: https://blog.learngoprogramming.com
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//
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// Copyright © 2018 Inanc Gumus
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// Learn Go Programming Course
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// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
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//
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package main
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import (
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"fmt"
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"os"
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"time"
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"github.com/mattn/go-runewidth"
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"github.com/inancgumus/screen"
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"golang.org/x/crypto/ssh/terminal"
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)
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func main() {
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const (
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cellEmpty = ' '
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cellBall = '⚾'
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maxFrames = 1200
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speed = time.Second / 20
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)
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var (
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px, py int // ball position
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vx, vy = 1, 1 // velocities
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cell rune // current cell (for caching)
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)
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// get the width and height
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width, height, err := terminal.GetSize(int(os.Stdout.Fd()))
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if err != nil {
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fmt.Println(err)
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return
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}
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// you can get the width and height using the screen package easily:
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// width, height := screen.Size()
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// get the rune width of the ball emoji
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ballWidth := runewidth.RuneWidth(cellBall)
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// adjust the width and height
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width /= ballWidth
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height-- // there is a 1 pixel border in my terminal
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// create the board
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board := make([][]bool, width)
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for column := range board {
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board[column] = make([]bool, height)
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}
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// drawing buffer length
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// *2 for extra spaces
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// +1 for newlines
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bufLen := (width*2 + 1) * height
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// create a drawing buffer
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buf := make([]rune, 0, bufLen)
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// clear the screen once
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screen.Clear()
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for i := 0; i < maxFrames; i++ {
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// calculate the next ball position
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px += vx
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py += vy
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// when the ball hits a border reverse its direction
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if px <= 0 || px >= width-1 {
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vx *= -1
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}
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if py <= 0 || py >= height-1 {
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vy *= -1
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}
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// remove the previous ball
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for y := range board[0] {
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for x := range board {
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board[x][y] = false
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}
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}
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// put the new ball
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board[px][py] = true
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// rewind the buffer (allow appending from the beginning)
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buf = buf[:0]
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// draw the board into the buffer
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for y := range board[0] {
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for x := range board {
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cell = cellEmpty
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if board[x][y] {
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cell = cellBall
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}
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buf = append(buf, cell, ' ')
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}
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buf = append(buf, '\n')
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}
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// print the buffer
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screen.MoveTopLeft()
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fmt.Print(string(buf))
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// slow down the animation
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time.Sleep(speed)
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}
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}
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