From 4021e83ab2180a99ddfd7f563599ba552d576162 Mon Sep 17 00:00:00 2001 From: Inanc Gumus Date: Fri, 22 Mar 2019 20:42:42 +0300 Subject: [PATCH] add: new exercises to bouncing ball --- .../exercises/05-no-slice/main.go | 110 ++++++++++++++++++ .../exercises/05-no-slice/solution/main.go | 81 +++++++++++++ 18-project-bouncing-ball/exercises/README.md | 19 ++- 3 files changed, 205 insertions(+), 5 deletions(-) create mode 100644 18-project-bouncing-ball/exercises/05-no-slice/main.go create mode 100644 18-project-bouncing-ball/exercises/05-no-slice/solution/main.go diff --git a/18-project-bouncing-ball/exercises/05-no-slice/main.go b/18-project-bouncing-ball/exercises/05-no-slice/main.go new file mode 100644 index 0000000..aeb790b --- /dev/null +++ b/18-project-bouncing-ball/exercises/05-no-slice/main.go @@ -0,0 +1,110 @@ +// 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" +) + +// --------------------------------------------------------- +// EXERCISE: No Slice +// +// Can you modify the program so that it doesn't use a +// slice for the board. You can use a slice for the buffer +// though. +// +// In this exercise, you'll understand that you don't +// have to use slices in any problem you encounter with. +// +// See what it feels like not using a slice for this +// solution. +// +// Think about why you have to use a slice for the buffer? +// +// Can there be any other solution? +// +// --------------------------------------------------------- + +func main() { + const ( + cellEmpty = ' ' + cellBall = '⚾' + + maxFrames = 1200 + speed = time.Second / 20 + + ivx, ivy = 1, 1 // initial velocities + ) + + var ( + px, py int // ball position + ppx, ppy int // previous ball position + vx, vy = ivx, ivy // velocities + + cell rune // current cell (for caching) + ) + + width, height := screen.Size() + width /= runewidth.RuneWidth(cellBall) + height-- // there is a 1 pixel border in my terminal + + // REMOVE THIS: create a single-dimensional board + board := make([]bool, width*height) + + // create a drawing buffer + // *2 for extra spaces + // +1 for newlines + buf := make([]rune, 0, (width*2+1)*height) + + 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-ivx { + vx *= -1 + } + if py <= 0 || py >= height-ivy { + vy *= -1 + } + + // remove the previous ball and put the new ball + pos := py*width + px + ppos := ppy*width + ppx + ppx, ppy = px, py + + board[pos], board[ppos] = true, false + + buf = buf[:0] + + 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') + } + + screen.MoveTopLeft() + fmt.Print(string(buf)) + + time.Sleep(speed) + } +} diff --git a/18-project-bouncing-ball/exercises/05-no-slice/solution/main.go b/18-project-bouncing-ball/exercises/05-no-slice/solution/main.go new file mode 100644 index 0000000..143655f --- /dev/null +++ b/18-project-bouncing-ball/exercises/05-no-slice/solution/main.go @@ -0,0 +1,81 @@ +// 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 + + // initial velocities + ivx, ivy = 1, 1 + ) + + var ( + px, py int // ball position + vx, vy = ivx, ivy // velocities + + cell rune // current cell (for caching) + ) + + width, height := screen.Size() + width /= runewidth.RuneWidth(cellBall) + height-- // there is a 1 pixel border in my terminal + + // create a drawing buffer + // *2 for extra spaces + // +1 for newlines + buf := make([]rune, 0, (width*2+1)*height) + + 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 + } + + buf = buf[:0] + + for y := 0; y < height; y++ { + for x := 0; x < width; x++ { + cell = cellEmpty + + if px == x && py == y { + cell = cellBall + } + + buf = append(buf, cell, ' ') + } + buf = append(buf, '\n') + } + + screen.MoveTopLeft() + fmt.Print(string(buf)) + + time.Sleep(speed) + } +} diff --git a/18-project-bouncing-ball/exercises/README.md b/18-project-bouncing-ball/exercises/README.md index 1209331..c39d25a 100644 --- a/18-project-bouncing-ball/exercises/README.md +++ b/18-project-bouncing-ball/exercises/README.md @@ -1,13 +1,22 @@ -# Exercises +# Bouncing Ball Exercises -1. **[Adjust the width and height automatically](https://github.com/inancgumus/learngo/tree/master/18-project-bouncing-ball/exercises/01-width-and-height)** +1. **[Find the Bug](https://github.com/inancgumus/learngo/tree/master/18-project-bouncing-ball/exercises/01-find-the-bug)** + + There is a bug in the bouncing ball code. Test yourself that you really understand how the backing arrays work. + + +2. **[Adjust the width and height automatically](https://github.com/inancgumus/learngo/tree/master/18-project-bouncing-ball/exercises/02-width-and-height)** In this exercise, your goal is getting the width and height of the terminal screen from your operating system (instead of setting the width and height manually). -2. **[Previous positions](https://github.com/inancgumus/learngo/tree/master/18-project-bouncing-ball/exercises/02-previous-positions)** +3. **[Previous positions](https://github.com/inancgumus/learngo/tree/master/18-project-bouncing-ball/exercises/03-previous-positions)** Let's optimize the program once more. This time you're going to optimize the clearing off the previous positions. -3. **[Use a single dimensional slice](https://github.com/inancgumus/learngo/tree/master/18-project-bouncing-ball/exercises/03-single-dimensional)** +4. **[Use a single dimensional slice](https://github.com/inancgumus/learngo/tree/master/18-project-bouncing-ball/exercises/04-single-dimensional)** - For the board slice, instead of using a multi-dimensional slice, let's use a single-dimensional slice. In this exercise, you'll understand and deeply internalize why I've used a multi-dimensional board slice. \ No newline at end of file + For the board slice, instead of using a multi-dimensional slice, let's use a single-dimensional slice. In this exercise, you'll understand and deeply internalize why I've used a multi-dimensional board slice. + +5. **[Don't use a slice for the board](https://github.com/inancgumus/learngo/tree/master/18-project-bouncing-ball/exercises/05-no-slice)** + + Expand your horizon: Don't use a slice for the board. You only need a slice for the buffer, only that. \ No newline at end of file