## Basic Concepts

### Coordinate axes

Metasequoia's 3D coordinate axis is organized as in the diagram on the right. It is a right-handed coordinate system. X is horizontal, Y is vertical, and Z is into and out of the screen. Notice the color coding: X is red, Y is green, and Z is blue.

### Document model

A Metasequoia document contains objects and materials.

It is necessary to run multiple copies of Metasequoia if you want to edit more than one Metasequoia document at once. You can use the Cut, Copy, and Past commands to exchange data between the different documents when you run two or more copies of the same version of Metasequoia.

### Objects

One document can contain two or more objects. Object panel You can use the object panel to perform "layer"-like operations, where some parts of your document are visible, but inactive, while other parts can be freely edited.

Objects are made up of three parts: vertices, edges, and faces. (Abbreviated V, E, and F.) Only front side of faces are displayed, and back side of faces are not visible. Only triangles and quads are allowed. Polygons with more than four edges are not allowed.

### Materials

Each face can be assigned a material, and the same material can be assigned to many faces. The Material Property Panel can be used to edit a material's properties (such as its color or texture). Any faces that don't have a material assigned to them automatically get a default material.

### Texture mapping and UV coordinates

Texture mapping is used to add realism and/or details to your models. UV coordinates are used to control which part of a texture is mapped to a face. Metasequoia contains several commands which allow you to edit the UV coordinates of an object's faces.

Texture maps can be specified using the Material Property Panel. The texture's data can be edited by using the Paint Panel. In addition, you can edit the texture by drawing directly on the 3D object in the 3D window, by using the Paint command.

### World / Screen / Local Coordinates

With some commands, such as the "Move" command, you can choose which coordinate system to use to perform the command. You can switch between coordinate systems by pressing the "W" and "S" buttons in the "Edit Option" panel.

You can edit along axes displayed at the base point in world coordinates, and you can edit horizontally or vertically on the screen in screen coordinates. Local coordinate is assigned to each object, and you can edit along the axes in local coordinates by [Move] command and so on after setting the local coordinates by [Local] command.