111 lines
2.2 KiB
Go
111 lines
2.2 KiB
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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"github.com/mattn/go-runewidth"
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)
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// ---------------------------------------------------------
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// EXERCISE: No Slice
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//
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// Can you modify the program so that it doesn't use a
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// slice for the board. You can use a slice for the buffer
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// though.
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//
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// In this exercise, you'll understand that you don't
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// have to use slices in any problem you encounter with.
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//
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// See what it feels like not using a slice for this
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// solution.
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//
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// Think about why you have to use a slice for the buffer?
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//
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// Can there be any other solution?
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//
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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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ivx, ivy = 1, 1 // initial velocities
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)
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var (
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px, py int // ball position
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ppx, ppy int // previous ball position
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vx, vy = ivx, ivy // velocities
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cell rune // current cell (for caching)
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)
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width, height := screen.Size()
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width /= runewidth.RuneWidth(cellBall)
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height-- // there is a 1 pixel border in my terminal
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// REMOVE THIS: create a single-dimensional board
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board := make([]bool, width*height)
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// create a drawing buffer
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// *2 for extra spaces
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// +1 for newlines
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buf := make([]rune, 0, (width*2+1)*height)
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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-ivx {
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vx *= -1
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}
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if py <= 0 || py >= height-ivy {
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vy *= -1
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}
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// remove the previous ball and put the new ball
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pos := py*width + px
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ppos := ppy*width + ppx
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ppx, ppy = px, py
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board[pos], board[ppos] = true, false
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buf = buf[:0]
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for y := 0; y < height; y++ {
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for x := 0; x < width; x++ {
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cell = cellEmpty
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if board[y*width+x] {
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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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screen.MoveTopLeft()
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fmt.Print(string(buf))
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time.Sleep(speed)
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}
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}
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