NAME

       glDrawElementsInstancedBaseInstance - draw multiple instances of a set of elements with offset applied to
       instanced attributes

C SPECIFICATION

       void glDrawElementsInstancedBaseInstance(GLenum mode, GLsizei count, GLenum type, const void * indices,
                                                GLsizei primcount, GLuitn baseinstance);

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.

       count
           Specifies the number of elements to be rendered.

       type
           Specifies the type of the values in indices. Must be one of GL_UNSIGNED_BYTE, GL_UNSIGNED_SHORT, or
           GL_UNSIGNED_INT.

       indices
           Specifies a pointer to the location where the indices are stored.

       primcount
           Specifies the number of instances of the specified range of indices to be rendered.

       baseinstance
           Specifies the base instance for use in fetching instanced vertex attributes.

DESCRIPTION

       glDrawElementsInstancedBaseInstance behaves identically to glDrawElements() except that primcount
       instances of the set of elements are executed and the value of the internal counter instanceID advances
       for each iteration.  instanceID is an internal 32-bit integer counter that may be read by a vertex shader
       as gl_InstanceID.

       glDrawElementsInstancedBaseInstance has the same effect as:

               if (mode, count, or type is invalid )
                   generate appropriate error
               else {
                   for (int i = 0; i < primcount ; i++) {
                       instanceID = i;
                       glDrawElements(mode, count, type, indices);
                   }
                   instanceID = 0;
               }

       Specific vertex attributes may be classified as instanced through the use of glVertexAttribDivisor().
       Instanced vertex attributes supply per-instance vertex data to the vertex shader. The index of the vertex
       fetched from the enabled instanced vertex attribute arrays is calculated as gl _ InstanceID divisor +
       baseInstance. Note that baseinstance does not affect the shader-visible value of gl_InstanceID.

NOTES

       glDrawElementsInstancedBaseInstance is available only if the GL version is 4.2 or greater.

       GL_LINE_STRIP_ADJACENCY, GL_LINES_ADJACENCY, GL_TRIANGLE_STRIP_ADJACENCY and GL_TRIANGLES_ADJACENCY are
       available only if the GL version is 3.2 or greater.

ERRORS

       GL_INVALID_ENUM is generated if mode is not one of GL_POINTS, GL_LINE_STRIP, GL_LINE_LOOP, GL_LINES,
       GL_TRIANGLE_STRIP, GL_TRIANGLE_FAN, or GL_TRIANGLES.

       GL_INVALID_VALUE is generated if count or primcount are negative.

       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 a non-zero buffer object name is bound to an enabled array and the
       buffer object's data store is currently mapped.

VERSION SUPPORT

       ┌────────────────────────────────────┬───────────────────────────────────────────────────────────────────────┐
       │                                    │                OpenGL Version                                         │
       ├────────────────────────────────────┼─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┤
       │Function                            │ 2.0 │ 2.1 │ 3.0 │ 3.1 │ 3.2 │ 3.3 │ 4.0 │ 4.1 │ 4.2 │ 4.3 │ 4.4 │ 4.5 │
       │/                                   │     │     │     │     │     │     │     │     │     │     │     │     │
       │Feature                             │     │     │     │     │     │     │     │     │     │     │     │     │
       │Name                                │     │     │     │     │     │     │     │     │     │     │     │     │
       ├────────────────────────────────────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
       │glDrawElementsInstancedBaseInstance │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  -  │  ✔  │  ✔  │  ✔  │  ✔  │
       └────────────────────────────────────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┘

SEE ALSO

       glDrawElements(), glDrawArraysInstanced()

COPYRIGHT

       Copyright © 2011-2014 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 © 2011-2014 Khronos Group

[FIXME: source]                                    01/03/2018                           GLDRAWELEMENTSINSTAN(3G)