feat: structure code samples to be runnable DRGTK games

This ensures we can easily test the code for a given chapter and verify
it does what is expected.

README.md

@@ -12,6 +12,18 @@ Run `mdbook serve` to boot up the web server that handles compiling everything.
 
 When the code is pushed to the `main` branch on GitHub, an action runs that deploys it to the `gh-pages` branch.
 
+## Running Samples
+
+The repository contains complete games for each separate code sample to ensure the code works and runs.
+
+Code samples live in `src/code` and then are organized by chapter and then sections within a chapter.
+
+Clone this book repository into a DragonRuby GTK engine directory and run the samples with:
+
+``` console
+./dragonruby book/src/code/chapter_03/01_input
+```
+
 ## Publishing
 
 The 3D cover file is generated with https://diybookcovers.com/

src/02-player-movement.md

@@ -142,7 +142,7 @@ You can move your dragon completely off the screen, lost in the great unknown! T
 [TODO: drawing about boundaries]
 
 ``` ruby
-{{#include code/chapter_02_movement_and_boundaries.rb}}
+{{#include code/chapter_02/app/main.rb}}
 ```
 
 Our dragon won't leave the screen. Woot woot! We've got some serious code here! Look at that logic. Here's what changed:
@@ -152,7 +152,7 @@ We moved the width and height of the player into variables so that they're easie
 Here's the good stuff. We check the boundary for the x axis:
 
 ``` ruby
-{{#include code/chapter_02_movement_and_boundaries.rb:20:26}}
+{{#include code/chapter_02/app/main.rb:20:26}}
 ```
 
 We check the right side of the screen: if the current player's x position plus their width is greater than `args.grid.w`, then we set the x position to the width of the screen (`args.grid.w`) minus the width of the sprite. For example, if we move the sprite so it has the x position of 1284, 4 pixels past the right edge of the screen, we override that change and set it to 1280 minus the player's width.

src/03-spit-fire.md

@@ -1,10 +1,22 @@
 # Spit Fire
 
-Our next mission is to make our dragon spit fire because that's just what they do. We'll piece this whole thing into a game with a narrative and intentional design soon enough. But let's keep focusing on simple mechanics and code for right now.
+Our next mission is to make our dragon spit fire because that's just what they do. We'll piece this whole thing into a game with win and lose states, a narrative, and intentional design soon enough. But let's keep focusing on simple mechanics and the code for right now.
 
 ## Fire on Input
 
-[ displaying a label ]
+In the last chapter, we used `args.inputs` to check for player input from the four main directions. If those inputs were being pressed, then we moved the dragon. Now let's check to see if the <kbd>Z</kbd> key is pressed to know when to have our dragon spit a fire ball.
+
+To check if a key was pressed, we can use `args.inputs.keyboard.key_down` and then whatever key we want to check. So in our case, we'll check `args.inputs.keyboard.key_down.z`. In our `#tick` method, right above where we render the dragon sprite, let's check for that input:
+
+``` ruby
+{{#include code/chapter_03/01_input/app/main.rb:36:40}}
+```
+
+Using `puts` is a really helpful way to check that our game works as we expect it to. In this case, every tick where the Z key is pressed down, it prints the string "Z key pressed" to the console (open it iwth <kbd>~</kbd>, remember?). Run your game and press the Z key a bunch and then open your console.
+
+<img alt="screenshot of DragonRuby console showing Z key pressed 6 times" src="./img/c03-console-puts.png" style="max-width: 420px">
+
+## Expanded Control Support
 
 ## Moving Fireballs
 

src/code/chapter_03/01_input/app/main.rb

@@ -0,0 +1,41 @@
+def tick args
+  args.state.player_x ||= 120
+  args.state.player_y ||= 280
+  speed = 12
+  player_w = 100
+  player_h = 80
+
+  if args.inputs.left
+    args.state.player_x -= speed
+  elsif args.inputs.right
+    args.state.player_x += speed
+  end
+
+  if args.inputs.up
+    args.state.player_y += speed
+  elsif args.inputs.down
+    args.state.player_y -= speed
+  end
+
+  if args.state.player_x +  player_w > args.grid.w
+    args.state.player_x = args.grid.w - player_w
+  end
+
+  if args.state.player_x < 0
+    args.state.player_x = 0
+  end
+
+  if args.state.player_y + player_h > args.grid.h
+    args.state.player_y = args.grid.h - player_h
+  end
+
+  if args.state.player_y < 0
+    args.state.player_y = 0
+  end
+
+  if args.inputs.keyboard.key_down.z
+    puts "Z key pressed"
+  end
+
+  args.outputs.sprites << [args.state.player_x, args.state.player_y, player_w, player_h, 'sprites/misc/dragon-0.png']
+end