R-Cade Games: Simulating the Legendary Game of Pong

By Peter Prevos

The legendary game of Pong

(This article was first published on The Devil is in the Data, and kindly contributed to R-bloggers)

Pong is one of the earliest arcade games on the market, first released in 1972. From the day I first saw this miracle box, I wanted to know more about computers.

I learnt how to write code from the 1983 book Dr. C. Wacko’s Miracle Guide to Designing and Programming your own Atari Computer Arcade Games. This book explains in a very clear and humorous way how to write computer games in Atari basic. I devoured this book and spent many hours developing silly games. This article is an ode to Dr Wacko, a computer geek’s midlife-crisis and an attempt to replicate the software I developed thirty years ago.

I showed in a previous post that R can be used for board games. The question is whether we create arcade games in R. My challenge is to recreate the look and feel of 1980s arcade games, or R-Cade games, using R? The code shown below simulates the legendary game of pong.

Playing Pong in R

The code is based on the Wacko’s Boing Program in the above-mentioned book. The R code is fully commented and speaks for itself. Please note that the animation is very clunky when you run it in RStudio. Only the native R Terminal displays the animation correctly.

Perhaps somebody can help me perfect this little ditty. I love to know how to read real-time USB input to control the game, so we get a step closer to the first R-Cade game.

The Pong Code

# Sound library
library(beepr) 

# Game parameters
skill <- 0.87 # Skill (0-1)
score <- 0
high.score <- 0

# Define playing field
par(mar = rep(1,4), bg = "black")
plot.new()
plot.window(xlim = c(0, 30), ylim = c(0, 30))
lines(c(1, 30, 30, 1), c(0, 0, 30, 30), type = "l", lwd = 5, col = "white")

# Playing field boundaries (depend on cex)
xmin <- 0.5
xmax <- 29.4
ymin <- 0.5
ymax <- 29.4

# initial position
x <- sample(5:25, 1)
y <- sample(5:25, 1)
points(x, y, pch = 15, col = "white", cex = 2)

# Paddle control
psize <- 4
ypaddle <- y

# Set direction
dx <- runif(1, .5, 1)
dy <- runif(1, .5, 1) 

# Game play 
while (x > xmin - 1) {
    sound <- 0 # Silence
    Sys.sleep(.05) # Pause screen. Reduce to increase speed
    points(x, y, pch = 15, col = "black", cex = 2) # Erase ball
    # Move ball
    x <- x + dx
    y <- y + dy 
    # Collision detection 
    if (x > xmax) {
        dx <- -dx * runif(1, .9, 1.1) # Bounce 
        if (x > xmin) x <- xmax # Boundary
        sound <- 10 # Set sound
        }
    if (y < ymin | y > ymax) {
        if (y < ymin) y <- ymin 
        if (y > ymax) y <- ymax
        dy <- -dy * runif(1, .9, 1.1)
        sound <- 10
    }
    # Caught by paddle?
    if (x < xmin & (y > ypaddle - (psize / 2)) & y < ypaddle + (psize / 2)) {
        if (x < xmin) x <- xmin
        dx <- -dx * runif(1, .9, 1.1)
        sound <- 2
        score <- score + 1
        }
    # Draw ball
    points(x, y, pch = 15, col = "white", cex = 2)
    if (sound !=0) beep(sound)
    # Move paddle
    if (runif(1, 0, 1) < skill) ypaddle <- ypaddle + dy # Imperfect follow
    # Draw paddle
    # Erase back line
    lines(c(0, 0), c(0, 30), type = "l", lwd = 8, col = "black")
    # Keep paddle inside window
    if (ypaddle < (psize / 2)) ypaddle <- (psize / 2) 
    if (ypaddle > 30 - (psize / 2)) ypaddle <- 30 - (psize / 2) 
    # Draw paddle 
    lines(c(0, 0), c(ypaddle - (psize / 2), ypaddle + (psize / 2)), type = "l", lwd = 8, col = "white") 
} 
beep(8) 
text(15,15, "GAME OVER", cex=5, col = "white") 
s <- ifelse(score == 1, "", "s")
text(15,5, paste0(score, " Point", s), cex=3, col = "white") 

The post R-Cade Games: Simulating the Legendary Game of Pong appeared first on The Devil is in the Data.

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