rgl.makemovie {rglplus}

Produce a movie from and 3d rgl scene

Description

Generates an MP4-movie of a 3d rgl scene with time-dependent objects and/or a camera path. The routine has been developed and tested for MacOS and it requires on a working installation of ffmpeg.

Usage

rgl.makemovie(
  frame = NULL,
  path = NULL,
  tmin = 0,
  tmax = 1,
  nframes = 60,
  fps = 60,
  output.path,
  output.filename,
  keep.frames = FALSE,
  quiet = TRUE,
  separator = .Platform$file.sep,
  ffmpeg.cmd = "ffmpeg",
  ffmpeg.opt = "-vcodec libx264 -crf 18 -pix_fmt yuv420p",
  manual = FALSE
)

Arguments

frame

optional function that plots or updates the 3D scene at a given time. This function must have exactly one argument, which specifies the time of the frame.

path

optional list that specifies the motion of the camera at some discrete times. The list contains the following elements (for more details see rgl.camera):

time = optional n-vector of strictly monotonically increasing discrete times, required if and only if one of the following four arguments (position, direction, up, fov) are provided as matrices/vectors. If not given, equally spaced in times between tmin and tmax are assumed.
position = optional argument specifying the camera position along the path. This argument must be one of three types: (1) A 3-element vector specifies a fixed camera position for the whole movie. (2) A n-by-3 matrix specifies n discrete camera positions at the exact times given in the time vector (see above). The code automatically generates a smooth function going through these n points. (3) A function f(t) of a single time variable t, which returns a 3-element vector, specifies the exact position at that time.
direction = optional argument specifying the direction of the camera's optical axis. This argument can be of the same three types as the position argument.
up = optional argument specifying the camera's up-direction. This argument can be of the same three types as the position argument.
fov = optional argument specifying the field-of-view (FoV) in degrees. Similarly to the above arguments, this can be either a single number (fixed FoV), a n-element vector (specifying the Fov at the n discrete times), or a scalar function (specifying the FoV at any time t).

tmin

physical time of first frame in the movie.

tmax

physical time of last frame in the movie.

nframes

number of frames in the movie. The time variable is sampled evenly between tmin and tmax.

fps

number of frames per second

output.path

character specifying the directory, where the movie and temporary frames are saved

output.filename

movie filename without path. This filename should end on the extension '.mp4'.

keep.frames

logical flag specifying whether the temporary directory with the individual frame files should be kept

quiet

logical flag; if true, all console outputs produced by 'ffmpeg' are suppressed

separator

filename separate of the system ('/' for Mac, Linux, Unix; '\' for Windows)

ffmpeg.cmd

command used to call ffmpeg form a terminal. Normally, this is just 'ffmpeg'.

ffmpeg.opt

optional arguments used with ffmpeg, such as compression and formatting options (see https://www.ffmpeg.org/ffmpeg.html).

manual

logical flag, if TRUE, ffmpeg is not run automatically. The ffmpeg command line is returned.

Details

Note that the frame width and height should be divisible by 2 for mp4 video compression to work.
To accelerate the movie generation, it is possible to suppress the screen update by calling rgl.hold before calling rgl.makemovie.

Value

Returns the command line to run ffmpeg in a terminal.

Author(s)

Danail Obreschkow

Examples

rgl.new(aspect=4/3, col='black', xlim=c(-4,4), ylim=c(-4,4), zlim=c(-4,4))
rgl::clear3d(type = "lights")
rgl::light3d(30,60,viewpoint.rel = FALSE)


# Make frame function
frame = function(t) {
  # t = time in seconds
  rgl.hold()
  if (t>0) {for (i in seq(3)) rgl::pop3d()}
  rgl.ball(0, 0, 0, 1, normals='improved', depth=6, png=system.file('earth.png', package='rglplus'),
           emission='#444466', rotation=rgl::rotationMatrix(t/86400*2*pi,0,0,1))
  alpha = seq(0,2*pi,length=360)+2*pi*t/43200
  alpha = c(alpha[1],rep(alpha[2:359],each=2),alpha[360])
  y = 3.168*cos(alpha)
  z = 3.168*sin(alpha)
  rgl.ball(0,y[1],z[1],0.05,col='red',emission='#aa0000')
  rgl::segments3d(0,y,z,col='red',alpha=seq(0,1,length=720))
  rgl.draw()
}

# Make path
path = list(position=c(10,10,0), up=c(0,0.5,1), fov = function(t) 40-t/8640)

# Produce movie
## Not run: 
rgl.makemovie(frame=frame, path=path, tmin=0, tmax=86400, output.path='~/testmovie',
              output.filename = 'movie.mp4', ffmpeg.cmd = 'ffmpeg', nframes=600)

## End(Not run)