Creates a directional light source. Directional light is located infinitely far away from the scene and always shines in the same direction. Because of the far distance, directional light rays are considered to be parallel by the time they reach the scene. Sun light is a good example of directional light. The marker will appear at the direction origin.

 

 

 

Creates an ambient light source. Ambient light is scattered so much by its environment that it cannot be attributed to any single source. Back lighting in a room is a good example of ambient light. Most of the light bounces off many objects before reaching your eyes. When ambient light strikes a surface it scatters in all directions. The marker will appear in the lower right corner of the graphics window.

 

 

 

Creates a light source that is always positioned at your point of view. The marker will appear in the lower right corner of the graphics window.

 

 

 

Creates a point light source. Point light shines equally in all directions like a light bulb. Two points are used to define the position and target. It might seem that a target is not needed. However, specifying a target provides an intuitive means of calculating the attenuation. The marker will appear at the position point. The marker will appear at the position point.

 

 

 

Creates a spot light source using two points. One to locate its position and the other to define its direction. The light emitted from a spot light originates at its position point and is restricted to the shape of a cone. The included angle of the cone is called the spread angle. The marker will appear at the position point.

 

 

 

Use this command to modify a light source. When you create a light source, a marker is created either at its origin or at the bottom-right corner of the graphics window depending on the type of light source.

 

You can also modify or inquire light sources by right-clicking on the light source markers (shown to the left of each command description above). An Object Editor popup menu will be displayed for additional options.

 

Select the light source marker to modify and then redefine the light source values. Refer to each light source command above.

 

 

 

Deletes a light source by selecting its marker (shown below the icons above).

 

 

 

Deletes all light sources in the active part (all light markers are removed from the graphics window).

 

 

 

Toggle the display of all light source markers (shown under the command icons above) on or off. The light sources are not deleted. Only the markers are toggled on or off.

 

 

 

• Direction - Specify the light source direction. The light source will shine only in the direction indicated.

• Position - Select a point to position the light source.

• Target - Select a point to target the light source.

 

 

 

• Name - Enter a name for the new light source.

• Color - Pick the color indicator and select a color from the Color Browser.

• Intensity - Refers to the amount of light emitted from the light source. Select the Intensity by moving the slider bar to a value from 0 to 1.

• Shadow - Turn the shadow from the light source On or Off.

• Constant, Linear Attenuation - The intensity value of the light decreases as the distance from the light increases. This is called attenuation. See Notes section below. Select the constant and linear attenuation by moving the slider bar to a value from 0 to 1.

• Spread Angle - Refers to the total included angle of the spot light's path. Refer to the figure above. Select the spread angle by moving the slider bar to a value from 1 to 180 degrees.

• Concentration - Refers to the amount of light concentrated at the center of the light source path. Select the concentration by moving the slider bar to a value from 0 to 128.

 

 

 

• OK - Creates the light source and places the light source marker shown for each command above.

• Apply - Preview the results of the light source on the part. Shaded display mode must be active.

• Cancel - Closes the menu without creating the light source.

 

 

 

• Attenuation Factor - The attenuation at each vertex (of the faceted shaded model) on the part is calculated internally by multiplying the intensity value by the following attenuation factor:
    

 

where
  

d = Distance between the light's position and a given vertex

k1 = Constant Attenuation Value

k2 = Linear Attenuation Value
  

Thus the intensity at a given vertex is:
  

 

The default value for k1 is 1.0 and the default value for k2 is 0.0. This makes the default attenuation factor 1.0. With these default settings, the intensity at each vertex is equal to the intensity value specified in the Point Light Source Form. Specifying constant and linear attenuation values that result in an attenuation factor of less than 1.0 will cause a varying decrease of intensity at each vertex. This is because the distance between each vertex and the light's position is calculated into the attenuation factor.