# Deterministically generated normal variates, implemented here in R but more
# useful for GLSL programming.

library(ggplot2)

fract <- function(x) x - floor(x)

rand <- function(x) fract(3482954.234 * sin(24934.342 * x + 12394.32))

norm <- function(x) {
  (rand(x) + rand(x + 17) + rand(x + 234) + rand(x + 456) +
     rand(x + 542) + rand(x + 586) + rand(x + 601) + rand(x + 723) +
     rand(x + 869) + rand(x + 901) + rand(x + 932) + rand(x + 998)
     - 6)
}

df <- data.frame(
  x = norm(1:10000),
  y = norm(10001:20000)
)

df2 <- data.frame(
  x = rnorm(10000),
  y = rnorm(10000)
)

ggplot(df, aes(x, y)) + geom_point(size = .1) + theme_bw()
ggplot(df2, aes(x, y)) + geom_point(size = .1) + theme_bw()

shapiro.test(df$x[1:4000])