light: add light source

Description

add a light source to the scene.

Usage

light3d(theta = 0, phi = 15, x = NULL, ...)
rgl.light( theta = 0, phi = 0, viewpoint.rel = TRUE, ambient = "#FFFFFF", 
           diffuse = "#FFFFFF", specular = "#FFFFFF", x = NULL, y = NULL, z = NULL)

Arguments

theta, phi

polar coordinates, used by default

viewpoint.rel

logical, if TRUE light is a viewpoint light that is positioned relative to the current viewpoint

ambient, diffuse, specular

light color values used for lighting calculation

x, y, z

cartesian coordinates, optional

...

generic arguments passed through to RGL-specific (or other) functions

Value

This function is called for the side effect of adding a light. A light ID is returned to allow rgl.pop to remove it.

Details

Up to 8 light sources are supported. They are positioned either in world space or relative to the camera. By providing polar coordinates to theta and phi a directional light source is used. If numerical values are given to x, y and z, a point-like light source with finite distance to the objects in the scene is set up. If x is non-null, xyz.coords will be used to form the location values, so all three coordinates can be specified in x.

Examples

Run this code

#
# a lightsource moving through the scene
#
data(volcano)
z <- 2 * volcano # Exaggerate the relief
x <- 10 * (1:nrow(z)) # 10 meter spacing (S to N)
y <- 10 * (1:ncol(z)) # 10 meter spacing (E to W)
zlim <- range(z)
zlen <- zlim[2] - zlim[1] + 1
colorlut <- terrain.colors(zlen) # height color lookup table
col <- colorlut[ z-zlim[1]+1 ] # assign colors to heights for each point

open3d()
bg3d("gray50")
surface3d(x, y, z, color=col, back="lines")
r <- max(y)-mean(y)
lightid <- spheres3d(1,1,1,alpha=0)
for (a in seq(-pi, pi, length.out=100)) {

    save <- par3d(skipRedraw=TRUE)
    clear3d(type = "lights")
    rgl.pop(id = lightid)
    xyz <- matrix(c(r*sin(a)+mean(x), r*cos(a) + mean(y), max(z)), ncol=3)
    light3d(x = xyz, diffuse = "gray75", 
            specular = "gray75", viewpoint.rel = FALSE) 
    light3d(diffuse="gray10", specular="gray25")
    lightid <- spheres3d(xyz, emission="white", radius=4)
    par3d(save)
    Sys.sleep(0.02)
}