GLMULTIDRAWELEMENTSI(3G)

NAME
glMultiDrawElementsIndirectCount - render indexed primitives from array data, taking parameters and count from memory

C SPECIFICATION

void glMultiDrawElementsIndirectCount(GLenum mode, GLenum type, const void *indirect, GLintptr drawcount, GLsizei maxdrawcount, 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.

type
    Specifies the type of data in the buffer bound to the GL_ELEMENT_ARRAY_BUFFER binding. Must be one of GL_UNSIGNED_BYTE, GL_UNSIGNED_SHORT, or GL_UNSIGNED_INT.

indirect
    Specifies the address of a structure containing an array of draw parameters.

drawcount
    Specifies an offset (in bytes) into the buffer object bound to the GL_PARAMETER_BUFFER binding point at which a single sizei typed value is stored. Must be a multiple of four.

maxdrawcount
    Specifies the maximum number of draws that are expected to be stored in the buffer. If the value stored at drawcount into the buffer is greater than maxdrawcount, the implementation stops processing draws after maxdrawcount parameter sets.

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

DESCRIPTION

glMultiDrawElementsIndirectCount specifies multiple geometric primitives with very few subroutine calls. glMultiDrawElementsIndirectCount behaves similarly to glMultiDrawElementsIndirect(), execept that the drawcount parameter is stored in the buffer bound to the GL_PARAMETER_BUFFER binding at the offset specified by drawcount.

The parameters addressed by indirect are packed into a structure that takes the form (in C):

        typedef  struct {
            uint  count;
            uint  instanceCount;
            uint  firstIndex;
            int  baseVertex;
            uint  baseInstance;
        } DrawElementsIndirectCommand;

If a buffer is bound to the GL_DRAW_INDIRECT_BUFFER binding at the time of a call to glMultiDrawElementsIndirectCount, 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.

Note that indices stored in client memory are not supported. If no buffer is bound to the GL_ELEMENT_ARRAY_BUFFER binding, an error will be generated.

The results of the operation are undefined if the reservedMustBeZero member of the parameter structure is non-zero. However, no error is generated in this case.

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

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.

GL_INVALID_OPERATION error is generated if no buffer is bound to the GL_PARAMETER_BUFFER binding point.

GL_INVALID_OPERATION error is generated if drawcount is not a multiple of four.

GL_INVALID_OPERATION error is generated if reading a sizei typed value from the buffer bound to the GL_PARAMETER_BUFFER target at the offset specified by drawcount would result in an out-of-bounds access.

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 | 4.6
glMultiDrawElementsIndirectCount | - | - | - | - | - | - | - | - | - | - | - | - | ✔

SEE ALSO

glDrawArrays(), glDrawArraysInstanced(), glDrawArraysIndirect(), glDrawElements(), glDrawRangeElements(), glDrawElementsIndirect(), glMultiDrawArraysIndirect() glMultiDrawArraysIndirectCount() glMultiDrawElementsIndirect()

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. https://opencontent.org/openpub/.

COPYRIGHT
Copyright © 2010-2014 Khronos Group.