Forum: help

RE: Decorating shapes in rgl [ Reply ]
By: Lars Relund on 2020-03-10 13:48

I found out how to add lines

# A plane using lines
plot3d(pts, xlim = c(-1,5), ylim = c(-1,5), zlim = c(-1,10), type = 'n')
normal <- c(1,1,1)
offset <- -3
lines <- 100
limits <- rgl::par3d()$bbox
m <- c(limits[1], limits[3], limits[5])
M <- c(limits[2], limits[4], limits[6])
# do a mesh
x <- seq(m[1], M[1], length.out = lines)
y <- seq(m[2], M[2], length.out = lines)
f <- function(x,y){-(normal[1]/normal[3])*x - (normal[2]/normal[3])*y - offset/normal[3]}
z <- outer(x,y,f)
z[z < m[3] | z > M[3]] <- NA
persp3d(x, y, z, back = 'lines', front = 'lines', add = TRUE)

# A polygon using lines
lines <- 50
plot3d(pts, xlim = c(-1,2), ylim = c(-1,2), zlim = c(-1,2), type = 'n')
pts <- data.frame(x = c(1,0,0,0.4), y = c(0,1,0,0.3), z = c(0,0,1,0.3))
polygon3d(pts, col = "white", polygon_offset = 1)
#' pts <- data.frame(x = c(1,0,0), y = c(0,1,0), z = c(0,0,1))
x <- pts[,1]
y <- pts[,2]
z <- pts[,3]
x0 <- seq(min(pts$x), max(pts$x), length.out = lines)
y0 <- seq(min(pts$y), max(pts$y), length.out = lines)
xy <- expand.grid(x0, y0)
xy[sp::point.in.polygon(xy[,1], xy[,2], pts$x, pts$y) <= 0,] <- NA
z0 <- predict(lm(z ~ x + y), newdata = data.frame(x=xy[,1], y=xy[,2]))
persp3d(x0, y0, z0, back = 'lines', front = 'lines', add = TRUE)

However, can you give an example on how to add texture to a plane?

RE: Decorating shapes in rgl [ Reply ] By: Duncan Murdoch on 2020-03-09 19:35	[forum:47460]
Sure, why not?

RE: Decorating shapes in rgl [ Reply ] By: Lars Relund on 2020-03-09 19:07	[forum:47459]
Cool. Would it be possible to draw lines / mesh inside the polygon too?

RE: Decorating shapes in rgl [ Reply ]
By: Duncan Murdoch on 2020-03-06 13:28

[forum:47457]

Here's some code showing both approaches:

library(rgl)
pts<-matrix(c(1,0,0,1,2,1,1,3,2,4,1,4), ncol = 3, byrow = TRUE)
x <- pts[,1]
y <- pts[,2]
z <- pts[,3]
z1 <- predict(lm(z ~ x + y))
pts <- cbind(x, y, z1)

filename <- tempfile(fileext = ".png")
png(filename = filename)
plot(1, 1, pch = 16, cex = 10, axes=FALSE, xlab="", ylab="")
dev.off()

open3d()
poly <- polygon3d(pts, plot = FALSE)
poly$texcoords <- rbind(x, y)*5
shade3d(poly, col = "white", specular = "black",
texture = filename)
decorate3d()

x0 <- seq(min(x), max(x), by = 0.1)
y0 <- seq(min(y), max(y), by = 0.1)
xy <- expand.grid(x0, y0)
xy <- xy[sp::point.in.polygon(xy[,1], xy[,2], x, y) > 0,]
xyz <- cbind(xy, predict(lm(z ~ x + y), newdata = data.frame(x=xy[,1], y=xy[,2])))

open3d()
polygon3d(pts, col = "white", polygon_offset = 1)
points3d(xyz)

RE: Decorating shapes in rgl [ Reply ]
By: Duncan Murdoch on 2020-03-06 10:51

[forum:47456]

That's not a valid polygon -- it's not planar. You can make it planar by fitting z to x + y using lm(), e.g.

x <- pts[,1]
y <- pts[,2]
z <- pts[,3]
z1 <- predict(lm(z ~ x+y))

Then you could use a texture to fill in the surface, but I don't think polygon3d supports textures very well. You'll need to figure out how to specify the texture correctly. Alternatively, just set up a grid of values in x and y, select those that lie in the polygon, predict the z value for each, and plot points.

Decorating shapes in rgl [ Reply ] By: Lars Relund on 2020-03-06 10:07	[forum:47455]
Assume the following polygon pts<-matrix(c(1,0,0,1,2,1,1,3,2,4,1,4), ncol = 3, byrow = TRUE) open3d() polygon3d(x = pts[,1], y = pts[,2], z = pts[,3]) axes3d() Is there a way to decorate the surface of the polygon with e.g. dots? I guess one way is to use a texture of a png file with a dot.