This is the tutorial for GLOTE, the GLASS Object Three-d
Editor. GLASS is a 3D object library that allows programs to use models with
articulated joints, that is simple translations, rotations, and scalings. More about
GLASS can be found out at the GLASS homepage.
The GLASS file format is plain text, by GLOTE gives an easy way to produce models.
GLOTE is written in C, and uses GTK+ to provide the
interface. GLASS is required on the system, and also
GtkGLArea. 3D hardware support
is not required, but recommended.
A brief summary of GLASS
Firstly I do recommend that you read the GLASS tutorial found on the GLASS website
(see above), but for the five second summary, see below.
At the core is the GLASS object, An object is made up of textures,
materials, triangle lists, variables, active points,
and components. These are summarised below:
Textures contain an RGB image file to be used in texturing.
Materials contain a set of lighting properties, and optionally a texture to be
Triangle lists are, well, lists of triangles. They describe a solid object. A triangle
list contains both alpha and non-alpha triangles, which are opaque and transparent
respectively. Each triangle has a colour, position, normal, and texture co-ordinate for
each vertex. Optionally a triangle may also have a material.
Variables are used to control transforms (translation/rotation etc), used in the GLASS
object during use. They have a minimum, maximum, and value.
Active points give feedback. They allow the user to retrieve information about the
position and direction of points in the GLASS object, no matter how the transforms
have moved them. They have an initial direction.
Components describe how the GLASS object joins together. The components are arranged into
a tree with children inheriting the transforms from their parents. A component can have a
transform, with values in that transform made up from constants or variables. A
component can have a triangle list, and finally an active point.
An example of a model is a robotic arm. The arm is made of two parts, a forearm, and
an upper arm (triangle lists). The arms are shiny (material), with
a logo on them (texture). The arms are linked by a hinge (variable),
and have a welding tip on the end of the forearm (active point). The arms
are connected with the forearm connected to the end of the base arm, the forearm
rotatable around the end of the base arm, and the welding tip connected to the end of
the forearm. (components).
Robert Cleaver Ancell
Last modified: Thu Aug 16 17:57:08 NZST 2001