Shadow Parameters

Reference

These are the parameters that control shadows:

Cast Shadows: Determines whether the current light casts shadows or not (off by default).

Use Global Settings: Set to use global settings for shadows cast by this light. Clear to enable individual control of the shadows. If you choose not to use the global settings, you must choose which method the renderer will use to generate shadows for this particular light.

When the Use Global Settings box is checked, the Bias, Size, and Sample Range spinners switch over to show you what the global settings are. This data is shared by every other light of this class. When the Use Global checkbox isn’t checked, the shadow parameters are specific to that particular light.

Use Shadow Maps / Use Ray-Traced Shadows: Determine whether the renderer uses shadow maps or ray-traced shadows to generate shadows for this light.

Map Bias: Map Bias moves the shadow toward or away from the shadow-casting object (or objects). Only used for shadow maps.

Size: Sets the size (in pixels squared) of the shadow map that’s computed for the light.

Smp Range: The sample range determines how much area within the shadow is averaged, which affects how soft the edge of the shadow is.

Absolute Map Bias: When this is on (the default), the bias for the shadow map is computed on an absolute basis, relative to all of the other objects in the scene. When it’s off, the bias is computed relative to the rest of the scene.

Note: This is the opposite of the way this parameter defaulted in 3D Studio Release 4. Defaulting to on should help avoid any shadow flicker problems.

Ray-Trace Bias: Ray-Trace Bias moves the shadow toward or away from the shadow-casting object (or objects). Only used for ray-traced shadows.

How To

To have a light cast shadows

• Set Cast Shadows.

The light will now cast shadows when you render the scene.

Note: With Overshoot turned on, spotlights cast light in all directions but cast shadows only within the falloff cone; directional lights cast light throughout the scene but cast shadows only within the falloff area.

To have a light use the global settings for shadows

• Set Use Global Settings.

When Use Global Settings is on, the other shadow controls (except Cast Shadows) are set to the values used by all other shadow-casting lights in the scene that have Use Global Settings set

Changing the affected parameters for one light with Use Global Settings set, changes them for all lights with Use Global Settings set.

To set a light's shadow parameters individually

• Clear Use Global Settings.

The settings revert to the individual settings for the light.

The default settings for shadow parameters are:

Use Shadow Maps = chosen
Map Bias = 40
Size = 256
Sample Range = 40
Absolute Map Bias = set
Ray Trace Bias = 0.2

You must also choose which method the renderer uses to generate shadows, either for a particular light or for all shadow-casting lights in the scene.

To cast shadow-mapped shadows

1. Choose Use Shadow Maps.
2. Use the Size spinner to set the size of the shadow map bitmap.
3. Use the Map Bias spinner to adjust the shadow offset, if necessary.
4. Use the Sample Range (Smp Range) spinner to create a soft-edged shadow.

To cast ray-traced shadows

1. Choose Use Ray-Traced Shadows.
2. Use the Ray Trace Bias spinner to adjust the shadow offset, if necessary.

To make an object not cast shadows

1. Select the object.
2. Right-click the object to pop up the object properties menu.
3. Choose Properties.

The Object Properties dialog appears.

4. Clear Cast Shadows, and then click OK.

Now when you render the scene, the object casts no shadows.

To make an object not receive shadows

1. Select the object.
2. Right-click the object to pop up the object properties menu.
3. Choose Properties.

The Object Properties dialog appears.

4. Clear Receive Shadows, and then click OK.

Now when you render the scene, the object receives no shadows.

Note: You can also prevent objects from casting shadows by excluding them from a light.