GLDRAWELEMENTSINSTAN(3G)        [FIXME: manual]       GLDRAWELEMENTSINSTAN(3G)

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 instancecount,
                                                GLuint 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.

       instancecount
           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 instancecount 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 < instancecount ; 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 instancecount is 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 / 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 |
       +------------------------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+
       |glDrawElementsInstancedBaseInstance |  -  |  -  |  -  |  -  |  -  |  -  |  -  |  -  | <?> | <?> | <?> | <?> |
       +------------------------------------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+

SEE ALSO
       glDrawElements(), glDrawArraysInstanced()

COPYRIGHT
       Copyright (C) 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.  https://opencontent.org/openpub/.

COPYRIGHT
       Copyright (C) 2011-2014 Khronos Group

[FIXME: source]                   10/20/2024          GLDRAWELEMENTSINSTAN(3G)