Figure 19: The "Light Editor" provides an intuitive, yet powerful interface to create and manipulate different kinds of lights.
The "Light Editor" provides utilities to create and modify the attributes of a light source. 3 different types of lights may be created -- "Directional" light, "Spot" light and "Point" light in addition to 2 other lights already present in the scene. ("Headlight" and "Ambient" light). Their attributes like color, on/off switch, position, direction, etc. may be set using the "Light Editor".
The "Light Editor" tool brings up the "Transform" tool also, so that you can use the latter to move any lights that you create (or have created).
Light Editor Controls
Light Name
This text field used to set the name of the light source for future reference. The names of headlight and ambient light cannot be changed. For all other lights, you can type in a new name by clicking the cursor in the text field, deleting the default name and choosing "Ok" after entering a new name.
Light list
This is a listing of all lights in the current Ez3d scene. By default, Ez3d creates an Ambient light source and a Headlight attached to the camera in the main view. The simplest way to select a light source is to "pick" the light icon in the main window. Lights may also be selected using this light list menu if the light icon is not displayed in the main window or if it is in such a position that it is inaccessible or inconvenient to select using the mouse in the main window.
Light type
A Ez3d light may be one of the following types:
Headlight
The headlight is a directional light that is always attached to the current camera position in the main view and moves with the camera. So this light affects all objects no mater what their positions might be. The headlight is often used for better viewing while modeling and usually turned off before rendering. A headlight cannot be created -- they can only be turned on or off.
Ambient
This light is like the sun. It has no location and affects all objects in the scene. It produces a constant illumination on all surfaces, regardless of their orientation. Unfortunately, ambient light by itself produces very unrealistic images since few real environments are illuminated solely by ambient light. There can be only one ambient light in the Ez3d scene. You cannot turn off the ambient light, but you can set its color (perhaps setting the color value to 0.0 if you want to "turn off" all ambient lighting).
Directional
This light illuminates uniformly along a particular direction. Since it is infinitely far away, it has no location in 3-D space. The icon for a directional light is for manipulating the direction only. An angular change of the light icon arrow produces an increase or decrease of light falling on the object. The angular shift in shadows is the same as would be expected in nature. This means that as you change the direction of the directional light, you will see a corresponding change in shadows.
Spot
This light works like the traditional spot light producing a tight and adjustable light source. It may be placed anywhere in the Ez3d environment and pointed in any direction. The cone of the light is adjustable in size.
Point
This light is like a star radiating light in all directions evenly. It is much like a solar source with the exception that it may be positioned anywhere in the Ez3d scene. It will produce proper sun rise shadow effects.
There is no limit on the number of spot lights, directional lights or point lights that can be created in Ez3d.
Edit Color
The light color editor is used to set the color of the light being edited. Please see section on "Attribute - Color" for more information on using the color editor. The light icon takes on the intrinsic color of the light.
Light Position Controls
Usding the "Light list", select the light that you want to manipulate. The "Transform" tool (see "Attribute - Transform" for details on its working) is the most accurate way to specify a light's position and direction (rotation). For directional and spot lights, you can also modify the light's direction by picking on the light icon's arrow and dragging it in the direction you want. For spotlights, you can change the cone angle by directly picking the cone of the icon and expanding or narrowing it. You can also specify the cone angle accurately by choosing "Attributes - Spotlight Options" in the top menu bar of the "Light Editor".
Point At Object
When you click on this button for a spot light or a directional light with an object in the scene selected, the light is oriented to point towards the center of the object. If you have more than one object selected, the light source points to the center of the object selected first.
Hint: The "Point At Object" option presents a convenient way to set a light's direction, after moving it to the desired location.
Light Editor Top Menu
The top menu in the "Light Editor" contains additional options:
Display - on/off
This toggle is used to turn on or off a light created in the "Light Editor". It simulates the effect of a real life light switch. By default, a light is turned "on" when created. You may then turn the light "off" any time you want and the light will not affect the scene. You can, of course, turn it "on" again anytime you wish. Ambient light is always "on".
Display - show icon
This toggle is used to turn on/off display of the light icon in the Ez3d environment. You may want to have the "show icon" option on if you want to manipulate the light's parameters using the light's icon in the main Ez3d view. Light icons visible in the Ez3d environment are not rendered in a test or final rendered image, or written to VRML.
Attributes - Cast Shadows
Turns on or off shadow casting ability of a light. This menu item is colored blue indicating that the effects of this selection are only visible in the final ray-traced image (See "Scene - Render Options")
Attributes - Spot Light Options
This option only works when the currently selected light is a spot light. When selected, it brings up the "Spot light Options" menu containing more options for a spot light:
Cone Angle
This slider sets the cone angle of a spot light. The spot light effects are felt only along a cone whose extent can be set with this slider.
Drop-off Rate
This slider sets the rate at which the light intensity of a spot light drops off from their primary direction.
Finally, you can use the following to create and delete lights in the scene:
Create
This button creates a light of the selected light type and other light parameters and adds it to the scene.
Delete
This button removes the currently selected light source from the Ez3d scene.
