Stage lighting in these modern days is a tool in the production of theater, dance, opera and other performance arts. There are several functions of Stage Lighting; it includes the Illumination, this is the simple ability of seeing what is occurring on stage. The lighting design will be ineffective if the audience has to strain to see the characters performing on stage unless this is the explicit intent of the production.  The altering of perception of shapes, particularly the three-dimensional stage element is what you called the Revelation of Form, one of the functions of Stage Lighting.  The other functions of Stage lighting is Focus or the directing of the audience’s attention to an area of the stage or distracting them from another.  Establishing or altering of position in time and space is the Location and time of day.  Lighting may be also used to project scenery or to act as scenery onstage; this called the Projection or the stage elements.  Alighting event may trigger or advance the action onstage, this is the Plot also one of the functions of Stage Lighting.  Lighting may be also used to show the area of the stage that the designer wants the audience to see and paint a picture, this functions of the Stage lighting is what you called the Composition.