Display lists improve performance because ________________________________________________

 

     You can use them to store OpenGL commands for later use. Calculations performed only once.

     A display list is precompiled after it is created. Geometric calculations are made only once.

 

  To optimize performance, an OpenGl display list is a _________________ of commands, rather than a

    dynamic database.  cache

 

  The text lists some most likely possibilities for optimization using display lists. List 3 of these.

 

      _________________________________________________________________________________

 

      _________________________________________________________________________________

 

      _________________________________________________________________________________

 

    (1) matrix operations,

    (2) raster bitmaps and images,

    (3) lights, material properties, and lighting models

    (4) polygon stipple patterns

 

  There are some disadvantages to using display lists. Describe 2 of these disadvantages.

 

      _________________________________________________________________________________

 

      _________________________________________________________________________________

 

    (1) Very small lists may not perform well since there is some overhead when executing a list.

    (2) The immutability of the contents of a display list. To optimize performance, an OpenGL display list cannot

           be  changed and its contents cannot be read.

    (3)If the application needs to maintain data separately from the display list (for example, for continued data

          processing), then a lot of additional memory may be required.

 

  The command to begin a display list   glNewList()

 

  The command to end a display list is glEndList()

 

  The command to invoke a display list is glCallList()

 

  You can have multiple display lists in a program. They are identified by: an integer index.

 

  glGenLists (range)

 

      What is the purpose of this function?

 

    To allocate a number of contiguous, previously unallocated  display list indices.

 

      What does it return?

 

    The index that marks the beginning of a contiguous block of empty list indices.

 

      What is the purpose of the range parameter?

 

    It specifies the number of indices requested.

 

  A hierarchical display list is useful for an object made of components, especially if some of the

    components are used multiple times. How do you create a hierarchical display list?

 

    By calling glCallList() between a glNewList() and glEndList() pair.

 

  What is the purpose of the function glIsList(list)?

 

    It returns a boolean – true if list is already used for a display list and false otherwise.

 

  Describe the procedure explained in the text for executing several display lists in succession.

 

    Place the display list indices in an array and call glCallLists()

 

  The text discusses how display lists can be used to manage state variables. What is a state variable?

 

    A variable that stores the current setting of things such as RGB color, and those associated with lighting, 

   texture, etc.

 

Indicate whether the following statements are true or false by placing a check ( ü) in the appropriate column.

 

Statement	True	False
Once a display list is created, it can be modified.		ü
A display list can contain only OpenGL commands.	ü
When a display list is compiled, only the values for expressions are stored in the list.	ü
Executing display lists is no slower than executing the commands contained within them individually.	ü
You are not guaranteed that your OpenGL implementation optimizes display lists for any particular application.	ü