Chapter 17 Lighting
491
Copyright Goodheart-Willcox Co., Inc.
AutoCAD Lights AutoCAD Lights
AutoCAD has three types of lighting: default lighting, sunlight with or without
sky illumination, and user-created lighting. Default lighting is the lighting automati-
cally available in the scene. It is composed of two light sources that evenly illuminate
all surfaces. As the viewpoint is changed, the light sources follow to maintain an even
illumination of the scene. There is no control over default lighting and it must be shut
off whenever one of the other types of lighting is used.
As you saw in Chapter 15, sunlight may be added to any scene. AutoCAD uses
a distant light to simulate the parallel rays of the sun. The date and time of day can
be adjusted to create different sunlight illumination. Sky illumination may also be
added with sunlight to simulate light bouncing off objects in the scene and particles in
the atmosphere. This helps create a more-natural feel.
User-created lighting results when you add AutoCAD light objects to the drawing.
There are four types of user-created lights: distant light, weblight, point light, and
spotlight. See Figure 17-5. A distant light is a directed light source with parallel light
rays. A weblight is a directional point light containing light intensity (photometric)
data. A point light is like a lightbulb with light rays shining out in all directions. A
spotlight is like a distant light, but it projects light in a cone shape instead of having
parallel light rays.
When created, point lights, weblights, and spotlights are represented by light
glyphs, or icons, in the drawing. To suppress the display of light glyphs, pick the
Light
Glyph Display
button in the expanded
Lights
panel on the
Visualize
tab of the ribbon.
The button is blue when light glyphs are displayed. The default lights, sun, and distant
lights are not represented by glyphs.
In this section, you will learn how to add lights. You will also learn how to adjust
the various properties of sunlight and AutoCAD light objects. The tools for working
with lights can be accessed using the command line, tool palettes, and the
Lights
and
Sun & Location
panels on the
Visualize
tab of the ribbon. See Figure 17-6.
So that you will never work with a completely dark scene, default lighting is applied
in the viewport and to the rendering if no other lights are added. In order for your
lights to be applied, you must switch between default lighting and user lighting. To do
this, pick the
Default Lighting
button in the expanded
Lights
panel on the
Visualize
tab
of the ribbon. This button toggles the lighting between default lighting and whatever
lights are available in the scene. When default lighting is on, the button is blue. When
off, the button is not highlighted. If you elected for AutoCAD to do so, the default
lighting will be automatically shut off when sunlight is turned on or a user-created
light is added to the scene.
LI
G
HT
G
LYPHDI
S
PLAY
Ribbon
Visualize
Lights
Light Glyph
Display
Type
LIGHTGLYPH-
DISPLAY
Figure 17-5.
AutoCAD has four
types of user-created
lights: distant,
point, weblight,
and spotlight. A
weblight is really a
targeted point light.
It projects in all
directions, but may
be predominant in
one direction.