Name

    NV_bindless_multi_draw_indirect_count

Name Strings

    GL_NV_bindless_multi_draw_indirect_count

Contact

    Christoph Kubisch, NVIDIA (ckubisch 'at' nvidia.com)

Contributors

    Piers Daniell, NVIDIA

Status

     DRAFT SPECIFICATION

Version

    Last Modified Date: July 6, 2015
    Revision: 3

Number

     OpenGL Extension #456

Dependencies

    NV_bindless_multi_draw_indirect is required.

    ARB_indirect_parameters is required.

    The extension is written against the OpenGL 4.3 Specification, Core Profile.

Overview

    This extension adds the possibility to define the number of drawcalls within
    a multi-draw-indirect call from the GPU, as provided by ARB_indirect_parameters,
    for the functions added in NV_bindless_multi_draw_indirect.


New Procedures and Functions

	void MultiDrawArraysIndirectBindlessCountNV(enum mode,
						    const void *indirect,
						    intptr drawCount,
						    sizei maxDrawCount,
						    sizei stride,
						    int   vertexBufferCount);

	void MultiDrawElementsIndirectBindlessCountNV(enum mode,
						      enum type,
						      const void *indirect,
						      intptr drawCount,
						      sizei maxDrawCount,
						      sizei stride,
						      int   vertexBufferCount);

New Tokens

    None.

Additions to Chapter 10 of the OpenGL 4.3 (Core) Specification (OpenGL Operation)

    Additions to Section 10.5, "Drawing Commands Using Vertex Arrays"

    After the description of MultiDrawArraysIndirectBindlessNV and before the
    introduction of DrawElementsOneInstance, insert the following on p.311:

	The command

	void MultiDrawArraysIndirectBindlessCountNV(enum mode,
						    const void *indirect,
						    intptr drawCount,
						    sizei maxDrawCount,
						    sizei stride,
						    int   vertexBufferCount);

    behaves similarly to MultiDrawArraysIndirectBindlessNV, except that <drawCount>
    defines an offset (in bytes) into the buffer object bound to the
    PARAMETER_BUFFER_ARB binding point at which a single <sizei> typed value
    is stored, which contains the draw count. <maxDrawCount> specifies the
    maximum number of draws that are expected to be stored in the buffer,
    and as in ARB_indirect_parameters the buffer must be sized accordingly.
    If the value stored at <drawCount> into the buffer is greater than
    <maxDrawCount>, an implementation may stop processing draws after
    <maxDrawCount> parameter sets.

    <drawCount> must be a multiple of four, otherwiseINVALID_VALUE error will
    be generated

    <maxDrawCount> must be positive, otherwise an INVALID_VALUE error will be
    generated.

    After the description of MultiDrawElementsIndirectBindlessNV  and before the
    introduction of MultiDrawElementsBaseVertex, insert the following on p.316:

	The command

	void MultiDrawElementsIndirectBindlessCountNV(enum mode,
						      enum type,
						      const void *indirect,
						      intptr drawCount,
						      sizei maxDrawCount,
						      sizei stride,
						      int   vertexBufferCount);

    behaves similarly to MultiDrawElementsIndirectBindlessNV, except that
    <drawCount> defines an offset (in bytes) into the buffer object bound
    to the PARAMETER_BUFFER_ARB binding point at which a single <sizei> typed
    value is stored, which contains the draw count. <maxDrawCount> specifies
    the maximum number of draws that are expected to be stored in the buffer,
    and as in ARB_indirect_parameters the buffer must be sized accordingly.
    If the value stored at <drawCount> into the buffer is greater than
    <maxDrawCount>, an implementation may stop processing draws after
    <maxDrawCount> parameter sets.

    <drawCount> must be a multiple of four, otherwise INVALID_VALUE error will
    be generated

    <maxDrawCount> must be positive, otherwise an INVALID_VALUE error will be
    generated.

    Modifications to Section 10.3.10 (p. 305) "Indirect Commands in Buffer Objects"

    Modify both instances of "DrawArraysIndirect, DrawElementsIndirect,
    MultiDrawArraysIndirect and MultiDrawElementsIndirect" on
    p. 305 to read "DrawArraysIndirect, DrawElementsIndirect,
    MultiDrawArraysIndirect, MultiDrawArraysIndirectARB, MultiDrawElementsIndirect,
    MultiDrawElementsIndirectCountARB, MultiDrawArraysIndirectBindlessNV,
    MultiDrawArraysIndirectBindlessCountNV, MultiDrawElementsIndirectBindlessNV
    and MultiDrawElementsIndirectBindlessCountNV".


Additions to the AGL/GLX/WGL Specifications

    None.

GLX Protocol

    None.

Errors

    INVALID_OPERATION is generated by MultiDrawArraysIndirectBindlessCountNV or
    MultiDrawElementsIndirectBindlessCountNV if no buffer is bound to the
    PARAMETER_BUFFER_ARB or DRAW_INDIRECT_BUFFER binding point.

    INVALID_VALUE is generated by MultiDrawArraysIndirectBindlessCountNV or
    MultiDrawElementsIndirectBindlessCountNV if <drawCount> is not aligned
    to found basic machine units.

    INVALID_VALUE is generated by MultiDrawArraysIndirectBindlessCountNV or
    MultiDrawElementsIndirectBindlessCountNV if <maxDrawCount> is not positive.

    INVALID_OPERATION is generated by MultiDrawArraysIndirectBindlessCountNV or
    MultiDrawElementsIndirectBindlessCountNV if reading a <sizei> typed value
    from the buffer bound to the PARAMETER_BUFFER_ARB target at the offset
    specified by <drawCount> would result in an out-of-bounds access.

New State

    None.

New Implementation Dependent State

    None.

Issues


Revision History

    Rev.    Date      Author	Changes
    ----  --------    --------	-----------------------------------------
     3    07/06/2015  ckubisch  stress that indirect buffer must be able to 
                                store <maxDrawCount> commands
     2	  06/24/2013  ckubisch	Sync to ARB_indirect_parameters
     1	  06/14/2013  ckubisch	Initial draft