glDrawElementsInstanced - draw multiple instances of a set of elements

voidglDrawElementsInstanced(GLenummode,GLsizeicount,GLenumtype,constvoid*indices,GLsizeiprimcount);

       Copyright © 2010-2014 Khronos Group

[FIXME: source]                                    11/18/2024                           GLDRAWELEMENTSINSTAN(3G)

glDrawElementsInstanced 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.

       glDrawElementsInstanced 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;
               }

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.

       glDrawElementsInstanced - draw multiple instances of a set of elements

glDrawElementsInstanced is available only if the GL version is 3.1 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.

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.

glDrawElements(), glDrawArraysInstanced()

       ┌─────────────────────────┬───────────────────────────────────────────────────────────────────────┐
       │                         │                OpenGLVersion                                         │
       ├─────────────────────────┼─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┬─────┤
       │ 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                    │     │     │     │     │     │     │     │     │     │     │     │     │
       ├─────────────────────────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┼─────┤
       │ glDrawElementsInstanced │  -  │  -  │  -  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │  ✔  │
       └─────────────────────────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┴─────┘