Re: [java3d] Material node's different types of colours

[Richard Smith - Systems Engineer - Melbourne]

Benedicte asks:

> do you know where I can find information about the different types of
> colours in a Material node ?
> (I would like to find definitions for : ambient colour, emissive colour,
> diffuse colour and specular colour).

AFAIK these are all related to a particular lighting model (but not the
only possible lighting model). OpenGL Programming Guide 2nd Ed p205
"The Mathematics of Lighting" has the details. I have at least another
reference explaining them model, but I don't have it with me at the moment.

The color calculated for each vertex is the sum of a number of contributions
from different lighting effects. The ambient colour, emissive colour,
diffuse colour and specular colours referred to above are actually parameters
used in the calculations. These calculations take into account not only
the various material properties, but also distance from light source(s),
the light source colour(s), spotlight effect, angle of incidence and more.

E.g. Diffuse Term

(max(L.n),0))*diffuse_light*diffuse_material

where L = (Lx,Ly,Lz) is the unit vector that points from the vertex to the
light position and n = (nx,ny,nz) is the unit normal vector at the vertex.

Richard.

============================================================================
   ,-_|\   Richard Smith - SE Melbourne
  /     \  Sun Microsystems Australia
[EMAIL PROTECTED]                     Phone : +61 3 9679 6200
  \_,-._/  Level 18, 60 Albert Rd            Direct : +61 3 9679 6224
       v   South Melbourne Vic 3205             Fax : +61 3 9696 0226
===========================================================================

=====================================================================
To subscribe/unsubscribe, send mail to [EMAIL PROTECTED]
Java 3D Home Page: http://java.sun.com/products/java-media/3D/