Yes. A white cube and all lights off to start with give me what I want. Many thanks!
J Dr James Foadi PhD Membrane Protein Laboratory (MPL) Diamond Light Source Ltd Diamond House Harewell Science and Innovation Campus Chilton, Didcot Oxfordshire OX11 0DE Email : james.fo...@diamond.ac.uk Alt Email: j.fo...@imperial.ac.uk -----Original Message----- From: Duncan Murdoch [mailto:murdoch.dun...@gmail.com] Sent: Thu 09/09/2010 18:00 To: Foadi, James (Imperial Coll.,RAL,DIA) Cc: r-help@r-project.org Subject: Re: [R] rgl and lighting On 09/09/2010 12:02 PM, james.fo...@diamond.ac.uk wrote: > Dear R community (and Duncan more specifically), > I can't work out how to make additional light sources work in rgl. > Here is the example. > > First I create a cube and visualize it: > > > cubo<- cube3d(col="black") > > shade3d(cubo) > > Next I position the viewpoint at theta=0 and phi=30: > > > view3d(theta=0,phi=30) > > Next, I want to create a 2nd light source which diffuses red light from the > front face. I thought I could do: > > >light3d(diffuse="red",theta=0,phi=0) > > but...the front side doesn't show any red-iness. Same goes for specular and > ambient. > What am I doing wrong here? How should the fron side show in red colour? Black doesn't reflect anything, so that's why you're not seeing the red. Colour the cube white, and you'll see it turn pink when you turn the red light on, or red if you turn off the default light first (using rgl.pop("lights")). Be aware that OpenGL (underlying rgl) has a fairly complicated lighting model. When you say col="black", you're only setting the "ambient" colour, i.e. the colour that appears the same in all directions. (It won't be the same on all faces of the cube, because the intensity depends on the incoming light.) There is also a "specular" component, which makes things appear shiny, because it's brighter from some viewpoints than others. It is normally white. Finally there's an "emission" component, which doesn't care about lighting, but is normally turned off. Lights also have 3 components, "ambient" (non-directional), "diffuse" (somewhat directional), and "specular" (highly directional). Duncan Murdoch > J > > Dr James Foadi PhD > Membrane Protein Laboratory (MPL) > Diamond Light Source Ltd > Diamond House > Harewell Science and Innovation Campus > Chilton, Didcot > Oxfordshire OX11 0DE > > Email : james.fo...@diamond.ac.uk > Alt Email: j.fo...@imperial.ac.uk > > -- This e-mail and any attachments may contain confidential...{{dropped:8}} ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
