ViewPlanSetUnderlayRange Method

Sets the underlay base and underlay top to the specified levels.

Namespace: Autodesk.Revit.DB
Assembly: RevitAPI (in RevitAPI.dll) Version: 25.0.0.0 (25.0.0.0)
Syntax
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public void SetUnderlayRange(
	ElementId baseLevelId,
	ElementId topLevelId
)

Parameters

baseLevelId  ElementId
The element id of a level in the project or InvalidElementId. If InvalidElementId, then the underlay base level is not set and no elements will be displayed as underlay.
topLevelId  ElementId
The element id of a level in the project or InvalidElementId. If InvalidElementId, then the underlay range is unbounded.
Exceptions
ExceptionCondition
ArgumentException The ElementId baseLevelId does not correspond to a Level in the project. -or- The ElementId topLevelId does not correspond to a Level in the project. -or- The elevation of level topLevelId must be greater than the elevation of level baseLevelId.
ArgumentNullException A non-optional argument was null
Example
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private void ViewUnderlay(ViewPlan planView, ElementId topLevelId, ElementId baseLevelId)
{
    if (planView.GetUnderlayOrientation() == UnderlayOrientation.LookingDown)
    {
        if (planView.GetUnderlayTopLevel() != topLevelId)
        {
            planView.SetUnderlayRange(baseLevelId, topLevelId);
        }

        planView.SetUnderlayOrientation(UnderlayOrientation.LookingUp);
    }
}
See Also