Add new game for examples showcase

snake-game/snake-game.rb

@@ -0,0 +1,102 @@
+require 'ruby2d'
+
+# size of one piece of the snake
+SPART_SIZE = 10
+
+set title: 'Snake Game', background: 'navy', fps_cap: 24
+
+snakeHead  = Square.new({ x: Window.width / 2,
+                          y: Window.height / 2,
+                          size: SPART_SIZE,
+                          color: 'green' })
+snake = [snakeHead]
+
+dir = {
+  x: SPART_SIZE,
+  y: 0
+}
+
+def newFood
+  Circle.new({ x: rand(SPART_SIZE..Window.width - SPART_SIZE),
+               y: rand(SPART_SIZE..Window.height - SPART_SIZE),
+               radius: SPART_SIZE / 2,
+               color: 'fuchsia' })
+end
+
+food             = newFood
+score            = 0
+gameover         = false
+drawGameOverText = false  # to draw the text once
+
+on :key do |e|
+  if e.type == :down
+    case e.key
+    when 'right'
+      dir = {x: SPART_SIZE, y: 0}
+    when 'down'
+      dir = {x: 0, y: SPART_SIZE}
+    when 'left'
+      dir = {x: -SPART_SIZE, y: 0}
+    when 'up'
+      dir = {x: 0, y: -SPART_SIZE}
+    when 'escape'
+      close
+    end
+  end
+end
+
+update do
+  if gameover
+    if drawGameOverText
+      txt = Text.new('Game Over',
+                    {x: Window.width / 2, y: Window.height / 2,
+                     size: 40,
+                     font: '../fonts/Ubuntu.ttf'})
+      txt.x -= txt.size * 2.5
+      txt.y -= txt.size
+      drawGameOverText = false
+    end
+  else
+    head = snake.shift
+    # detect collision
+    if head.contains?( food.x - food.radius, food.y + food.radius ) ||
+       head.contains?( food.x - food.radius, food.y - food.radius ) ||
+       head.contains?( food.x + food.radius, food.y - food.radius ) ||
+       head.contains?( food.x + food.radius, food.y + food.radius )
+          # snake grows
+          newPart = Square.new({x: head.x, y: head.y,
+                                  size: SPART_SIZE,
+                                  color: 'green'})
+          snake.push( newPart )
+          # create food at random location
+          Window.remove( food )
+          food = newFood
+    end
+    prevX = head.x
+    prevY = head.y
+    snake.each do |part|
+      part.x, prevX = prevX, part.x
+      part.y, prevY = prevY, part.y
+    end
+    # move
+    head.x += dir[:x]
+    head.y += dir[:y]
+    # if hit one edge goes to the oposite one
+    head.x = head.x % Window.width
+    head.y = head.y % Window.height
+    # hit itself
+    snake.each do |part|
+      if head.contains?( part.x + 1, part.y + 1 ) ||
+         head.contains?( part.x + 1, part.y + part.size - 1 ) ||
+         head.contains?( part.x + part.size - 1, part.y + 1 ) ||
+         head.contains?( part.x + part.size - 1, part.y + part.size - 1 )
+          gameover = true
+          drawGameOverText = true
+          break
+      end
+    end
+    snake.unshift( head )
+  end
+end
+
+show