GLDISPATCHCOMPUTEIND(3G) OpenGL Manual GLDISPATCHCOMPUTEIND(3G)NAME
glDispatchComputeIndirect - launch one or more compute work groups using parameters stored in a buffer
C SPECIFICATION
void glDispatchComputeIndirect(GLintptr indirect);
PARAMETERS
indirect
The offset into the buffer object currently bound to the GL_DISPATCH_INDIRECT_BUFFER buffer target at which the dispatch parameters are
stored.
DESCRIPTION
glDispatchComputeIndirect launches one or more compute work groups using parameters stored in the buffer object currently bound to the
GL_DISPATCH_INDIRECT_BUFFER target. Each work group is processed by the active program object for the compute shader stage. While the
individual shader invocations within a work group are executed as a unit, work groups are executed completely independently and in
unspecified order. indirect contains the offset into the data store of the buffer object bound to the GL_DISPATCH_INDIRECT_BUFFER target
at which the parameters are stored.
The parameters addressed by indirect are packed a structure, which takes the form (in C):
typedef struct {
uint num_groups_x;
uint num_groups_y;
uint num_groups_z;
} DispatchIndirectCommand;
A call to glDispatchComputeIndirect is equivalent, assuming no errors are generated, to:
cmd = (const DispatchIndirectCommand *)indirect;
glDispatchComputeIndirect(cmd->num_groups_x, cmd->num_groups_y, cmd->num_groups_z);
}
Unlike glDispatchCompute(), no error is generated if any of the num_groups_x, num_groups_y or num_groups_z members of the
DispatchIndirectCommand is larger than the value of GL_MAX_COMPUTE_WORK_GROUP_COUNT for the corresponding dimension. In such circumstances,
behavior is undefined and may lead to application termination.
ERRORS
GL_INVALID_OPERATION is generated if there is no active program for the compute shader stage.
GL_INVALID_VALUE is generated if indirect is less than zero or not a multiple of four.
GL_INVALID_OPERATION is generated if no buffer is bound to the GL_DISPATCH_INDIRECT_BUFFER target or if the command would source data
beyond the end of the buffer object's data store.
ASSOCIATED GETS
glGet() with argument GL_MAX_COMPUTE_WORK_GROUP_COUNT
SEE ALSO
glDispatchCompute().
COPYRIGHT
Copyright (C) 2012 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
opengl.org 06/10/2014 GLDISPATCHCOMPUTEIND(3G)
Check Out this Related Man Page
GLDRAWARRAYSINDIRECT(3G) OpenGL Manual GLDRAWARRAYSINDIRECT(3G)NAME
glDrawArraysIndirect - render primitives from array data, taking parameters from memory
C SPECIFICATION
void glDrawArraysIndirect(GLenum mode, const void *indirect);
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 a structure containing the draw parameters.
DESCRIPTION
glDrawArraysIndirect specifies multiple geometric primitives with very few subroutine calls. glDrawArraysIndirect behaves similarly to
glDrawArraysInstancedBaseInstance(), execept that the parameters to glDrawArraysInstancedBaseInstance() are stored in memory at the address
given by indirect.
The parameters addressed by indirect are packed into a structure that takes the form (in C):
typedef struct {
uint count;
uint primCount;
uint first;
uint baseInstance;
} DrawArraysIndirectCommand;
const DrawArraysIndirectCommand *cmd = (const DrawArraysIndirectCommand *)indirect;
glDrawArraysInstancedBaseInstance(mode, cmd->first, cmd->count, cmd->primCount, cmd->baseInstance);
If a buffer is bound to the GL_DRAW_INDIRECT_BUFFER binding at the time of a call to glDrawArraysIndirect, 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 glDrawArraysIndirect have an unspecified value after glDrawArraysIndirect 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.
ERRORS
GL_INVALID_ENUM is generated if mode is not an accepted value.
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(),
COPYRIGHT
Copyright (C) 2010 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
opengl.org 06/10/2014 GLDRAWARRAYSINDIRECT(3G)