.LWO File Format

Introduction

LWO2 is the object format of LightWave 3D from version 6.0, which replaced the older LWOB. NewTek documented it in its software development kit; the description is dated 9 November 2001, and later copies add a few chunks from newer releases of LightWave.

Besides points, polygons and surfaces, an LWO2 file can hold several layers, vertex maps for texture coordinates, weights, colours and morphs, subdivision patches, skeleton bones, animated parameters (envelopes), references to images (clips), and surfaces built from stacked texture layers and shader plug-ins.

Structure

An LWO2 file is an IFF file: one big-endian FORM chunk with the form type LWO2, holding further chunks, each a four-letter ID, a 4-byte length and the data. Chunks may come in any order, except that a chunk refers to the most recent chunk of the kind it depends on: POLS to the latest PNTS, PTAG to the latest POLS and TAGS. A LAYR chunk starts each layer.

In this reference

• Data types and chunks – the data types and every top-level chunk: layers, points, vertex maps, polygons and their types, tags, bounding box, description and icon
• Envelopes and clips – the ENVL and CLIP chunks and all their sub-chunks
• Surface parameters – the SURF chunk and its basic sub-chunks
• Surface blocks – texture layers and shaders: block headers, ordinal strings, texture mapping, image maps, procedurals and gradients

Variants

• LightWave object (LWOB) – the original form, written by LightWave 5 and earlier
• LightWave object (LWO2) – the form from LightWave 6 on, with layers, vertex maps and surface blocks

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