Control Light Properties (Procedure)

AutoCAD 2008 User's Guide > Create Realistic Images and Graphics > Add Lighting to Your Model > Adjust and Manipulate Lights > Control Light Properties >

Control Light Properties

Concept

Procedure

Quick Reference

To set attenuation in a point light or a spotlight

At the Command prompt, enter lightingunits and set the value to 0 for standard lighting.
Click Tools menu Palettes Properties.
Click the light glyph, or select the light in the Lights in Model window.
In the Properties palette under Attenuation, set Use Limits to Yes, or select a type of attenuation:
- None. Sets no attenuation. Objects far from the point light are as bright as objects close to the light.
- Inverse Linear. Sets attenuation to be the inverse of the linear distance from the light. For example, at a distance of 2 units, light is half as strong as at the point light; at a distance of 4 units, light is one quarter as strong. The default value for inverse linear is half the maximum intensity.
- Inverse Square. Sets attenuation to be the inverse of the square of the distance from the light. For example, at a distance of 2 units, light is one quarter as strong as at the point light; at a distance of 4 units, light is one sixteenth as strong.
If you set Use Limits to Yes, enter the following values in the properties palette or use the grip tool in the drawing to set the limits:
- Start Limit Offset. Specifies the point where light starts as an offset from the center of the light. The default is 0.
- End Limit Offset. Specifies the point where light ends as an offset from the center of the light. No light is cast beyond this point.
  
  NoteAttenuation start limits and end limits are not supported by the OpenGL driver (wopengl9.hdi), but are supported by the Direct 3D driver (direct3d9.hdi). To identify your driver, enter 3dconfig, and click Manual Tune. Look at the selected Driver Name in the Manual Performance Tuning dialog box.