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Overview

Selecting this menu item pops up a window that allows you to manipulate the light sources and shading of three-dimensional plots.

Lighting window

The Lighting window should look similar to Lighting window when it pops up. If you are using MeshTV's defaults, most controls in this window will be grayed out and disabled.

This window allows you to modify light source settings and attributes, which change the shading on many three-dimensional plots.

For every window, you can choose between two pre set lighting layouts or specify a custom one. If you decide to create your own, you have control over the type, direction, and brightness of up to eight different light sources. In addition, there is a preview area which indicates what the layout will look like when it is applied.

If you don't see a description for an item in this window, check in the Shared items section near the front of the chapter.

Lighting layout

There are two preset lighting layouts you can choose. The first is MeshTV's default lighting, labeled Standard . This layout has two opposite-facing white light sources that are positioned relative to the mesh. One points in the direction <-1.4, -1.0, -0.7>, and the other faces <1.4, 1.0, 0.7>.

The second preset layout is entitled Eye . This layout has a single light source that is positioned relative to the viewer and that always points directly away from the viewer. This light source faces in the direction <0, 0, -1>.

You can also choose to create a custom lighting layout for each window. If you select the Custom layout, then the remaining controls on the window become available to modify and preview light sources. You can create a different custom layout for each visualization window, and these will all be saved in your MeshTV configuration file.

Light selection

This control selects which light sources are shown in the preview area and are being modified. In addition, the labels for any light sources which are currently turned on will be in a different color.

When using a preset layout, this control is always set to show All light sources. When defining a custom layout, any option may be selected.

When this is set to All , all light sources will be shown in the preview area, and the controls to modify the light source properties will be disabled. When this is set to a single light source, 1 through 8 , then only that light will be shown in the preview area, and it can be modified through the Properties controls.

Light properties

When a custom light source has been selected, the controls in this area of the window can be used to modify the properties of that light source.

The toggle button labeled On turns on and off the light. Once a light has been turned on, it will be visible in the preview window and you can modify other properties of that light.

The light Type can be Directional , Eye or Ambient . A Directional light is one that stays fixed to the model. An Eye light is one which stays fixed to the viewer. An Ambient light has no direction; it is used to set a background level of illumination so that unlit areas are not completely black.

When the light is a directional or eye light, the Direction can be modified. You can enter the x, y, and z components of its direction in this text field. If the light is an ambient light, it has no direction and this field will be disabled.

The Brightness value determines the intensity of the illumination from this light. A very low value (towards the left) adds almost no illumination to the scene, and a high value adds the most. The indicator to the right of this slider will show black for a low brightness and white for a high brightness.

Light preview

This area shows what the cumulative effect of the currently selected lights will have on the scene. It also shows the types and positions (when applicable) of all selected lights.

Several objects are drawn in this preview area. The sphere is illuminated with the active light sources to give a rough impression of the shading effect on the scene. It is surrounded by a box which helps give orientation information. The x-axis is colored red, the y-axis green, and the z-axis blue. Directional lights are shown as yellow cones, and eye lights are shown as blue arrows. Any ambient lights are shown as light bulbs in the lower left corner of this preview area.

When All lights are selected, this area will show all lights which are turned on. In this mode, when the left mouse button is pressed and held in this area, dragging the mouse will rotate the scene so that you may see it from any angle. When the middle mouse button is pressed in this area, the rotation will return to the normal angle.

When a single light, 1 through 8 , is selected, this area will show the selected light if it is on. In this mode, when the left mouse button is pressed and held in this area, dragging the mouse will change this light source's direction. (If the active light is an ambient light, this has no effect.) The middle mouse button will reset the rotation to the normal angle when pressed.