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GLMULTIDRAWELEMENTSI(3G) | [FIXME: manual] | GLMULTIDRAWELEMENTSI(3G) |
NAME¶
glMultiDrawElementsIndirect - render indexed primitives from array data, taking parameters from memoryC SPECIFICATION¶
void
glMultiDrawElementsIndirect(GLenum mode,
GLenum type,
const void *indirect,
GLsizei drawcount,
GLsizei stride);
PARAMETERS¶
modeSpecifies 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.
type
Specifies the type of data in the buffer bound to the
GL_ELEMENT_ARRAY_BUFFER binding.
indirect
Specifies the address of a structure containing an array
of draw parameters.
drawcount
Specifies the number of elements in the array addressed
by indirect.
stride
Specifies the distance in basic machine units between
elements of the draw parameter array.
DESCRIPTION¶
glMultiDrawElementsIndirect specifies multiple indexed geometric primitives with very few subroutine calls. glMultiDrawElementsIndirect behaves similarly to a multitude of calls to glDrawElementsInstancedBaseVertexBaseInstance(), execpt that the parameters to glDrawElementsInstancedBaseVertexBaseInstance() 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 a structure that takes the form (in C):typedef struct { uint count; uint instanceCount; uint firstIndex; uint baseVertex; uint baseInstance; } DrawElementsIndirectCommand;
GLsizei n; for (n = 0; n < drawcount; n++) { const DrawElementsIndirectCommand *cmd; if (stride != 0) { cmd = (const DrawElementsIndirectCommand *)((uintptr)indirect + n * stride); } else { cmd = (const DrawElementsIndirectCommand *)indirect + n; } glDrawElementsInstancedBaseVertexBaseInstance(mode, cmd->count, type, cmd->firstIndex + size-of-type, cmd->instanceCount, cmd->baseVertex, cmd->baseInstance); }
NOTES¶
The baseInstance member of the DrawElementsIndirectCommand 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_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 no buffer is bound to the GL_ELEMENT_ARRAY_BUFFER binding, or if such a buffer's data store is currently mapped. 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.VERSION SUPPORT¶
OpenGL Version | ||||||||||||
Function / Feature Name | 2.0 | 2.1 | 3.0 | 3.1 | 3.2 | 3.3 | 4.0 | 4.1 | 4.2 | 4.3 | 4.4 | 4.5 |
glMultiDrawElementsIndirect | - | - | - | - | - | - | - | - | - | ✔ | ✔ | ✔ |
SEE ALSO¶
glDrawArrays(), glDrawArraysInstanced(), glDrawArraysIndirect(), glDrawElements(), glDrawRangeElements(), glDrawElementsIndirect(), glMultiDrawArraysIndirect()COPYRIGHT¶
Copyright © 2010-2014 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/.COPYRIGHT¶
Copyright © 2010-2014 Khronos Group.08/26/2014 | [FIXME: source] |