Suppose I have three meshes A, B, C in one VBO and used glMultiDrawElementsIndirect with the instance count set to 1, 0, and 1 for A, B, and C respectively and the draw count set to 3. What would be the value of gl_DrawID in the vertex shader? Would it be 0 for (vertices of) A, 1 for B, 2 for C or would it skip B and assign 1 to C?

The reference website states that this is “equivalent” to calling multiple glDrawElementsInstancedBaseVertexBaseInstance as much as the draw count so the answer should be the first case.