Next Previous Contents

Introduction

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
    Textures contain an RGB image file to be used in texturing.
  • materials
    Materials contain a set of lighting properties, and optionally a texture to be applied.
  • triangle lists
    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
    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
    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
    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).

    Next Previous Contents
    Robert Cleaver Ancell
    Last modified: Thu Aug 16 17:57:08 NZST 2001