XXX - Not complete yet!!! Name EXT_compiled_vertex_array Name Strings GL_EXT_compiled_vertex_array Version $Date: 1996/11/21 00:52:19 $ $Revision: 1.3 $ Number 97 Dependencies None Overview This extension defines an interface which allows static vertex array data to be cached or pre-compiled for more efficient rendering. This is useful for implementations which can cache the transformed results of array data for reuse by several DrawArrays, ArrayElement, or DrawElements commands. It is also useful for implementations which can transfer array data to fast memory for more efficient processing. For example, rendering an M by N mesh of quadrilaterals can be accomplished by setting up vertex arrays containing all of the vertexes in the mesh and issuing M DrawElements commands each of which operate on 2 * N vertexes. Each DrawElements command after the first will share N vertexes with the preceding DrawElements command. If the vertex array data is locked while the DrawElements commands are executed, then OpenGL may be able to transform each of these shared vertexes just once. Issues * Is compiled_vertex_array the right name for this extension? * Should there be an implementation defined maximum number of array elements which can be locked at a time (i.e. MAX_LOCKED_ARRAY_SIZE)? Probably not, the lock request can always be ignored with no resulting change in functionality if there are insufficent resources, and allowing the GL to define this limit can make things difficult for applications. * Should there be any restrictions on what state can be changed while the vertex array data is locked? Probably not. The GL can check for state changes and invalidate any cached vertex state that may be affected. This is likely to cause a performance hit, so the preferred use will be to not change state while the vertex array data is locked. New Procedures and Functions void LockArraysEXT (int first, sizei count) void UnlockArraysEXT (void) New Tokens Accepted by the parameter of GetBooleanv, GetIntegerv, GetFloatv, and GetDoublev: ARRAY_ELEMENT_LOCK_FIRST_EXT 0x81A8 ARRAY_ELEMENT_LOCK_COUNT_EXT 0x81A9 Additions to Chapter 2 of the 1.1 Specification (OpenGL Operation) After the discussion of InterleavedArrays, add a description of array compiling/locking. The currently enabled vertex arrays can be locked with the command LockArraysEXT. When the vertex arrays are locked, the GL can compile the array data or the transformed results of array data associated with the currently enabled vertex arrays. The vertex arrays are unlocked by the command UnlockArraysEXT. Between LockArraysEXT and UnlockArraysEXT the application should ensure that none of the array data in the range of elements specified by and are changed. Changes to the array data between the execution of LockArraysEXT and UnlockArraysEXT commands may affect calls may affect DrawArrays, ArrayElement, or DrawElements commands in non-sequential ways. While using a compiled vertex array, references to array elements by the commands DrawArrays, ArrayElement, or DrawElements which are outside of the range specified by and are undefined. Additions to Chapter 3 of the 1.1 Specification (Rasterization) None Additions to Chapter 4 of the 1.1 Specification (Per-Fragment Operations and the Frame Buffer) None Additions to Chapter 5 of the 1.1 Specification (Special Functions) LockArraysEXT and UnlockArraysEXT are not complied into display lists but are executed immediately. Additions to Chapter 6 of the 1.1 Specification (State and State Requests) None Additions to the GLX Specification XXX - Not complete yet!!! GLX Protocol XXX - Not complete yet!!! Errors INVALID_VALUE is generated if LockArrarysEXT parameter is less than zero. INVALID_VALUE is generated if LockArraysEXT parameter is less than or equal to zero. INVALID_OPERATION is generated if LockArraysEXT is called between execution of LockArraysEXT and corresponding execution of UnlockArraysEXT. INVALID_OPERATION is generated if UnlockArraysEXT is called without a corresponding previous execution of LockArraysEXT. INVALID_OPERATION is generated if LockArraysEXT or UnlockArraysEXT is called between execution of Begin and the corresponding execution of End. New State Initial Get Value Get Command Type Value Attrib --------- ----------- ---- ------- ------ ARRAY_ELEMENT_LOCK_FIRST_EXT GetIntegerv Z+ 0 client-vertex-array ARRAY_ELEMENT_LOCK_COUNT_EXT GetIntegerv Z+ 0 client-vertex-array New Implementation Dependent State None