Set up the background of the scene.
bg3d(color, sphere=FALSE, back="lines", fogtype="none", fogScale = 1, col, ...)
See Details below.
TRUE, an environmental sphere geometry is used for the background decoration.
Specifies the fill style of the sphere geometry. See
material3d for details.
linear fog function
exponential fog function
squared exponential fog function
Fog only applies to objects with
fog set to
Scaling for fog. See Details.
Additional material properties. See
material3d for details.
The background color is taken from
color is missing.
The first entry
is used for background clearing and as the fog color.
The second (if present) is used for background sphere geometry.
col are both missing, the default is found in
r3dDefaults$bg list, or
"white" is used
if nothing is specified there.
sphere is set to
TRUE, an environmental
sphere enclosing the whole scene is drawn.
If not, but the material properties include a bitmap as a texture, the bitmap is drawn in the background of the scene. (The bitmap colors modify the general color setting.)
If neither a sphere nor a bitmap background is drawn, the background is filled with a solid color.
fogScale parameter should be a positive value
to change the density of the fog in the plot. For
fogtype = "linear" it multiplies the density of the
fog; for the exponential fog types it multiplies the density
parameter used in the display.
the OpenGL 2.1 reference
for the formulas used in the fog calculations within R (though the
"exp2" formula appears to be wrong, at least on my
system). In WebGL displays,
the following rules are used. They appear to match the
rules used in R on my system.
"linear" fog, the near clipping plane is
taken as \(c=0\), and the
far clipping plane is taken as \(c=1\). The
amount of fog is \(s * c\) clamped to a 0 to 1
range, where \(s = fogScale\).
"exp2" fog, the observer location
is negative at a distance depending on the field of view.
The formula for the distance is
$$c = [1-sin(theta)]/[1 + sin(theta)]$$
where \(theta = FOV/2\).
We calculate $$c' = d(1-c) + c$$
so \(c'\) runs from 0 at the observer to
1 at the far clipping plane.
"exp" fog, the amount of fog is
\(1 - exp(-s * c')\).
"exp2" fog, the amount of fog is
\(1 - exp[-(s * c')^2]\).
open3d() # a simple white background bg3d("white") # the holo-globe (inspired by star trek): bg3d(sphere = TRUE, color = c("black", "green"), lit = FALSE, back = "lines" ) # an environmental sphere with a nice texture. bg3d(sphere = TRUE, texture = system.file("textures/sunsleep.png", package = "rgl"), back = "filled" ) # The same texture as a fixed background open3d() bg3d(texture = system.file("textures/sunsleep.png", package = "rgl"), col = "white")