NAME

       glMultiDrawArraysIndirect - render multiple sets of primitives from array data, taking
       parameters from memory

C SPECIFICATION

       void glMultiDrawArraysIndirect(GLenum mode, const void *indirect, GLsizei drawcount,
                                      GLsizei stride);

PARAMETERS

       mode
           Specifies what kind of primitives to render. Symbolic constants GL_POINTS,
           GL_LINE_STRIP, GL_LINE_LOOP, GL_LINES, GL_LINE_STRIP_ADJACENCY, GL_LINES_ADJACENCY,
           GL_TRIANGLE_STRIP, GL_TRIANGLE_FAN, GL_TRIANGLES, GL_TRIANGLE_STRIP_ADJACENCY,
           GL_TRIANGLES_ADJACENCY, and GL_PATCHES are accepted.

       indirect
           Specifies the address of an array of structures containing the draw parameters.

       drawcount
           Specifies the the number of elements in the array of draw parameter structures.

       stride
           Specifies the distance in basic machine units between elements of the draw parameter
           array.

DESCRIPTION

       glMultiDrawArraysIndirect specifies multiple geometric primitives with very few subroutine
       calls.  glMultiDrawArraysIndirect behaves similarly to a multitude of calls to
       glDrawArraysInstancedBaseInstance(), execept that the parameters to each call to
       glDrawArraysInstancedBaseInstance() are stored in an array in memory at the address given
       by indirect, separated by the stride, in basic machine units, specified by stride. If
       stride is zero, then the array is assumed to be tightly packed in memory.

       The parameters addressed by indirect are packed into an array of structures, each element
       of which takes the form (in C):

               typedef  struct {
                   uint  count;
                   uint  instanceCount;
                   uint  first;
                   uint  baseInstance;
               } DrawArraysIndirectCommand;

       A single call to glMultiDrawArraysIndirect is equivalent, assuming no errors are generated
       to:

               GLsizei n;
               for (n = 0; n < drawcount; n++)
               {
                   const DrawArraysIndirectCommand  *cmd;
                   if (stride != 0)
                   {
                       cmd = (const DrawArraysIndirectCommand  *)((uintptr)indirect + n * stride);
                   }
                   else
                   {
                       cmd = (const DrawArraysIndirectCommand  *)indirect + n;
                   }

                   glDrawArraysInstancedBaseInstance(mode,  cmd->first,  cmd->count,  cmd->instanceCount, cmd->baseInstance);
               }

       If a buffer is bound to the GL_DRAW_INDIRECT_BUFFER binding at the time of a call to
       glMultiDrawArraysIndirect, indirect is interpreted as an offset, in basic machine units,
       into that buffer and the parameter data is read from the buffer rather than from client
       memory.

       In contrast to glDrawArraysInstancedBaseInstance(), the first member of the parameter
       structure is unsigned, and out-of-range indices do not generate an error.

       Vertex attributes that are modified by glMultiDrawArraysIndirect have an unspecified value
       after glMultiDrawArraysIndirect returns. Attributes that aren't modified remain well
       defined.

NOTES

       The baseInstance member of the DrawArraysIndirectCommand structure is defined only if the
       GL version is 4.2 or greater. For versions of the GL less than 4.2, this parameter is
       present but is reserved and should be set to zero. On earlier versions of the GL, behavior
       is undefined if it is non-zero.

       glMultiDrawArraysIndirect is available only if the GL version is 4.3 or greater.

ERRORS

       GL_INVALID_ENUM is generated if mode is not an accepted value.

       GL_INVALID_VALUE is generated if stride is not a multiple of four.

       GL_INVALID_VALUE is generated if drawcount is negative.

       GL_INVALID_OPERATION is generated if a non-zero buffer object name is bound to an enabled
       array or to the GL_DRAW_INDIRECT_BUFFER binding and the buffer object's data store is
       currently mapped.

       GL_INVALID_OPERATION is generated if a geometry shader is active and mode is incompatible
       with the input primitive type of the geometry shader in the currently installed program
       object.

       GL_INVALID_OPERATION is generated if mode is GL_PATCHES and no tessellation control shader
       is active.

SEE ALSO

       glDrawArrays(), glDrawArraysInstanced(), glDrawElements(), glDrawRangeElements(),
       glDrawArraysIndirect(), glMultiDrawElementsIndirect()

COPYRIGHT

       Copyright © 2012-2013 Khronos Group. This material may be distributed subject to the terms
       and conditions set forth in the Open Publication License, v 1.0, 8 June 1999.
       http://opencontent.org/openpub/.

AUTHORS

       opengl.org