Space Game R Code

Here you will find the source code for the space game, as described in the upcoming book Graphic Guide to R

Copyright 2018 Antony Lees

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0 

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

settings <- function() {
  # screen size
  size(600,400)  
}

setup <- function() {
  initialise_ship()

  # black background
  background(0)
  # white lines
  stroke(255)
  
  score <<- 0
}

draw <- function() {
  # redraw the background
  background(0)
  # draw the targeting lines so that they leave a space around the mouse pointer
  line(0, 0, mouseX - 20, mouseY- 20)
  line(width, 0, mouseX + 20, mouseY - 20)
  line(0, height, mouseX - 20, mouseY + 20)
  line(width, height, mouseX + 20, mouseY + 20)
  # display the current mouse coordinates
  coord_text <- paste("(", mouseX, ",", mouseY,")")
  text(coord_text, mouseX, mouseY)
  
  # draw the ship
  rectMode(CENTER)
  rect(ship_x, ship_y, 5, 5)
  # left wing
  line(ship_x - 10, ship_y - 10, ship_x - 10, ship_y + 10)
  line(ship_x, ship_y, ship_x - 10, ship_y)
  # right wing
  line(ship_x + 10, ship_y - 10, ship_x + 10, ship_y + 10)
  line(ship_x, ship_y, ship_x + 10, ship_y)
  
  # update coordinates for next time
  ship_x <<- ship_x + x_direction
  ship_y <<- ship_y + y_direction

  # if current coordinates mean the ship has left the screen
  if (ship_x < 0 || ship_x > width || ship_y < 0 || ship_y > height) {
    # new ship
    initialise_ship()
  }
  
  # display near the top of the screen
  score_text <- paste("Score", score)
  text(score_text, width/2, 10)
}

initialise_ship <- function() {
  # choose random direction
  x_direction <<- random(-2, 2)
  y_direction <<- random(-2, 2)
  # start in the middle of the screen
  ship_x <<- width/2
  ship_y <<- height/2
}

mouseClicked <- function() {
  # fire!
  stroke(0, 255, 0)
  strokeWeight(3)
  line(0, height/2, mouseX, mouseY)
  line(width, height/2, mouseX, mouseY)
  # reset colour
  stroke(255)
  strokeWeight(1) 
  # if the left mouse button was clicked
  if (mouseButtonVar == LEFT) {
    # if the button was pressed in the region of the ship
    if (mouseX > (ship_x - 10) && mouseX < (ship_x + 10)) {
      score <<- score + 1
      initialise_ship()
    }
  }
}