Added this from old VirtualScenes repository, which we are phasing out.

Signed-off-by: David Brainard <brainard@psych.upenn.edu>

Utilities/rtbBuildDesription.m

+%% Get a formatted struct describing a light, material, etc.
+%   @param category a scene element category like 'light', 'material', etc.
+%   @param type a scene element type like 'area', 'matte', etc.
+%   @param propertyNames cell aray of element property names like {'intensity', 'diffuseReflectance'}
+%   @param propertyValues cell aray of element property values like {'D65.spd, '255 0 0'}
+%   @param valueTypes cell aray of property values types like {'spectrum', 'rgb'}
+%
+% @details
+% Builds a struct with standard formatting that describes some scene
+% element.  This struct will be suitable for writing to a RenderToolbox3
+% mappings file using utilities like AppendMappings().
+%
+% @details
+% @a category and @a type indicate the kind of scene element to describe,
+% for example an area light or matte material.
+%
+% @details
+% @a propertyNames, @a propertyValues, and @a valueTypes all should have
+% n elements, and collectively specify n properties of the scene element.
+%
+% @details
+% See <a
+% href="https://github.com/DavidBrainard/RenderToolbox3/wiki/Generic-Scene-Elements">Generic-Scene-Elements</a>
+% for examples of valid elements and properties.
+%
+% @details
+% Returns a struct with standard formatting which describes a scene element
+% and its properties.
+%
+% @details
+% Usage:
+%   description = rtbBuildDesription(category, type, propertyNames, propertyValues, valueTypes)
+%
+% We should update the commenting style of this header someday.
+
+function description = rtbBuildDesription(category, type, propertyNames, propertyValues, valueTypes)
+properties = struct( ...
+    'propertyName', propertyNames, ...
+    'propertyValue', propertyValues, ...
+    'valueType', valueTypes);
+
+description = struct( ...
+    'category', category, ...
+    'type', type, ...
+    'properties', properties);