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I am interested in generating 3D reasoning items in R. To this end I have adapted some of the awesome functions built in the rgl library to my ends. My new function is ‘cube’ and it takes position and automatically sizes itself as a 1x1x1 cube though this can be adjusted through the scale argument.

Find the code on github

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# Easy Bordered Cubes in R

library('rgl'); library('magrittr')

cube <- function(x=0,y=0,z=0, bordered=TRUE,

filled = TRUE, lwd=2, scale=1,

fillcol = gray(.95),

bordercol ='black', ...) {

mycube <- cube3d()

# Reduce size to unit

mycube$vb[4,] <- mycube$vb[4,]/scale*2

for (i in 1:length(x)) {

# Add cube border

if (bordered) {

bcube <- mycube

bcube$material$lwd <- lwd

bcube$material$front <- 'line'

bcube$material$back <- 'line'

bcube %>% translate3d(x[i], y[i], z[i]) %>% shade3d

}

# Add cube fill

if (filled) {

fcube <- mycube

fcube$vb[4,] <- fcube$vb[4,]*1.01

fcube$material$col <- fillcol

fcube %>% translate3d(x[i], y[i], z[i]) %>% shade3d

}

}

}

clear3d()

cube(0,0,0)

cube(1,0,0, filled=F)

cube(-1,0,0, bordered=F)

movie3d(spin3d(axis=c(0,0,1), rpm=20), duration=2.95)

# I mapped R using an excel spreadsheet which

# translated Xs into 2D locations points

clear3d()

y <- c(1,1,1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,4,5,5,

5,5,6,6,6,6,7,7,7,7,7,8,8,8,8,9,9,9,9,10,

10,10,10,11,11,11,11,11,12,12,12,12,12)

x <- c(8,7,6,3,2,1,7,6,3,2,6,5,3,2,6,5,4,3,2,5,4,

3,2,5,4,3,2,6,5,4,3,2,7,6,3,2,7,6,3,2,7,6,

3,2,6,5,4,3,2,5,4,3,2,1)

z <- cummax(y)*.5

length(x)==length(y)

cube(x,y,z)

movie3d(spin3d(axis=c(0,0,1), rpm=20), duration=2.95)

# Let's see how sin and cos can work together

z <- seq(0,6,.1)

x <- sin(pi*z)*z

y <- cos(pi*z)*z

clear3d()

cube(x,y,z*2, scale=.75)

movie3d(spin3d(axis=c(0,0,1), rpm=20), duration=2.95)

# Now let's look at some of the prototyping for

# my 3D reasoning items.

clear3d()

vlist <- c(0,0,0)

for (i in 1:15) {

cube(vlist[1],vlist[2],vlist[3])

step <- sample(1:3, 1)

vlist[step] <- vlist[step]+(-1)^rbinom(1,1,.25)

}

rgl.material(shininess=1)

bg3d("white")

clear3d(type = "lights")

rgl.viewpoint(theta = 90, phi = 0, fov = 0)

rgl.snapshot("2014-09-09angle1.png")

rgl.viewpoint(theta = 0, phi = 0, fov = 0)

rgl.snapshot("2014-09-09angle2.png")

rgl.viewpoint(theta = 0, phi = 90, fov = 0)

rgl.snapshot("2014-09-09angle3.png")

rgl.light()

rgl.viewpoint(theta = 180, phi = 20, fov = 60)

rgl.snapshot("2014-09-09cubes3d1.png")

rgl.viewpoint(theta = -20, phi = -20, fov = 60)

rgl.snapshot("2014-09-09cubes3d2.png")

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