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glDrawArraysIndirect

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_TRIANGLE_STRIP, GL_TRIANGLE_FAN, and GL_TRIANGLES 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 glDrawArraysInstanced, except that the parameters to glDrawArraysInstanced 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  reserved;
    } DrawArraysIndirectCommand;

    const DrawArraysIndirectCommand  *cmd  = (const DrawArraysIndirectCommand  *)indirect;
    glDrawArraysInstanced(mode,  cmd->first,  cmd->count,  cmd->primCount);

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 glDrawArraysInstanced, 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 reserved member of the DrawArraysIndirectCommand structure should be set to zero. 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.

API Version Support

OpenGL ES API Version
Function Name 2.0 3.0 3.1
glDrawArraysIndirect - -
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