R Under development (unstable) (2025-07-22 r88445 ucrt) -- "Unsuffered Consequences"
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> library(grid)
> library(gridSVG)

Attaching package: 'gridSVG'

The following objects are masked from 'package:grid':

    linearGradient, pattern, radialGradient

The following object is masked from 'package:grDevices':

    dev.off

> 
> dev.new(width=6, height=6)
dev.new(): using pdf(file="Rplots10.pdf")
> 
> grid.newpage()
> # Some default settings
> pushViewport(viewport(gp=gpar(col="black", fill=NA)))
> 
> n <- 30
> L <- 50 #mm
> A <- 20 #mm
> t <- seq(0, 2*pi, length=n)
> x <- A*cos(t)
> v <- -A*sin(t)
> theta <- atan(x/L)
> y <- L*cos(theta)
> 
> pushViewport(viewport(layout=grid.layout(4, 1,
+                          widths=unit(2.2*A, "null"),
+                          heights=unit(c(1, L + 10, 2.2*A, 2),
+                            c("lines", "null", "null", "lines")),
+                          respect=TRUE)))
> pushViewport(viewport(layout.pos.row=2,
+                        xscale=A * c(-1.1, 1.1),
+                        yscale=c(0, L + 10)))
> grid.rect()
> grid.lines(name="chain",
+            x=unit(c(0.5, x[1]), c("npc", "native")),
+            y=unit(1, "npc") - unit(c(0, abs(y)[1]), c("npc", "native")))
> grid.animate("chain",
+              x=animUnit(unit(c(rep(0.5, n), x),
+                              c(rep(c("npc", "native"), each=n))),
+                         timeid=rep(1:n, 2)),
+              y=animUnit(unit.c(unit(rep(1, n), "npc"),
+                         unit(1, "npc") - unit(y, "native")),
+                         timeid=rep(1:n, 2)),
+              duration=5, rep=TRUE)
> grid.circle(name="weight",
+             x=unit(x[1], "native"),
+             y=unit(1, "npc") - unit(y[1], "native"),
+             r=unit(1, "mm"),
+             gp=gpar(fill="black"))
> grid.animate("weight",
+              x=unit(x, "native"),
+              y=unit(1, "npc") - unit(abs(y), "native"),
+              duration=5, rep=TRUE)
> popViewport()
> 
> pushViewport(viewport(layout.pos.row=3,
+                        xscale=A * c(-1.1, 1.1),
+                        yscale=A * c(-1.1, 1.1)))
> grid.rect()
> grid.lines(x=unit(c(0, 0), "native"),
+            gp=gpar(lty="dashed", col="grey"))
> grid.lines(y=unit(c(0, 0), "native"),
+            gp=gpar(lty="dashed", col="grey"))
> grid.text("Displacement", y=unit(-1, "lines"))
> grid.text("Velocity", x=unit(-1, "lines"), rot=90)
> grid.circle(name="key",
+             x=unit(x[1], "native"),
+             y=unit(v[1], "native"),
+             r=unit(1, "mm"),
+             gp=gpar(fill="black"))
> grid.animate("key",
+              x=unit(x, "native"),
+              y=unit(v, "native"),
+              duration=5, rep=TRUE)
> popViewport(2)
> 
> popViewport()
> 
> grid.export("pendulum.svg")
> 
> dev.off()
null device 
          1 
> 
> proc.time()
   user  system elapsed 
   0.60    0.09    0.68