X3D shape and geometry

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X3D tutorials

Introduction

This short tutorial introduced basic X3D modeling concepts.

Prerequisites: X3D, X3D graphics principles and X3D shape and geometry

In X3D, 3D "things" are defined with shape nodes. Shape nodes can appear under any grouping node (including the Scene node). Usually, a geometry is included under at least a Transform node for positioning, rotation, etc.

A Shape node includes:

• A mandatory geometry node, of which several exist
• An optional (quasi-mandatory) Appearance node which in turn includes a Material node for coloring.

X3D includes several kinds of geometry nodes:

1. Simple geometric primitives
2. Points, lines and polygone nodes
3. Geometric 2D nodes
4. Triangle nodes

Translations and color

In order to position geometric shapes we need to use a so-called Transform node and in order to see a node we need to color it. Below we just introduce a minimal design pattern that you should use and understand before playing with geometry nodes.

The translation="2 0 0" attribute of the Transform node allows to position an object in the x,y and z axis. The code below will move the containing object two meters to the right along the x-axis.

The Appearence node allows to add various colors and textures to an objet. In our case we define a simple Material with a diffuseColor of red (RGB value = "1 0 0").

  <Transform translation='2 0 0'>
            <Shape>
		<!-- A single geometry node here -->
                <Box size="2 2 2"/>
		<!-- A simple RGB color for appearence, e.g. a 100% red cube -->
                <Appearance>
                    <Material diffuseColor="1.0 0 0"/>
                </Appearance>
            </Shape>
 </Transform>

Geometric primitives

The five geometric primitives are most often used for hand coding, and implementation details (i.e. tessellation/polygon count) is left to the client.

Links

Reference manuals

• Node Reference (very incomplete as of oct. 2010)
• X3D Tooltips (ok)
• X3D Scene Authoring Hints