   The glDrawRangeElementsBaseVertex Problems
  Hi, I have a VBO which will store vertices of some models.the vertex format of each model is different from other model in the same VBO.i want to render each single model in the VBO independently .according to some search on the web , i found the glDrawRangeElementsBaseVertex  may be suitable for my situation, but i dont know  the exact meaning of parameters of this function. Could someone who has had experience using this function give me explanation of the parameter? thanks .   
  I've never used it myself, but I think this should be all you need:GL_ARB_draw_elements_base_vertex;  If i specify some number BV as BaseVertex in the function, Does it means that all the format of vertices in the range [0 + Offset, BV+ offset] is same as the vertice that will be rendered by glDrawRangeElementsBaseVertex?  (offset is the numnber specified by the latest call of glVertexPointer )i,e. (1) glVertexPointer(offset)// specifying the offset in VBO (2) glDrawRangeElementsBaseVertex(BV)// is the vertice from offset to BV same as the verices that will be rendered?   ;  FOR EXAMPLE: THERE ARE 2 MODELS struct POSITION{   FLOAT P[3];};struct NORMAL{   FLOAT N[3];};MODEL0: VERTICES: P0,P1,P2,P3,N0,N1,N2,N3 INDICES:  0,1,2,3,2,1MODEL1: VERTICES: P4,P5,P6,P7,P8,P9,N4,N5,N6,N7,N8,N9 INDICES:  0,2,3,1,4,5,1I STORE VERTICES OF ALL MODELS IN A SINGLE VERTEXBUFFER AND INDEX BUFFER.VERTEX BUFFER:  P0,P1,P2,P3,N0,N1,N2,N3,  P4,P5,P6,P7,P8,P9,N4,N5,N6,N7,N8,N9INDEX  BUFFER:  0,1,2,3,2,1,    0,2,3,1,4,5,1I ONLY WANT TO RENDER  MODEL1, SO ,FOR MODEL1: BindVertexBufferBindIndexBufferVertexPointer(...,  SIZEOF(POSITION)*4 + SIZEOF(NORMAL)*4);NormalPointer(...,  SIZEOF(POSITION)*4 + SIZEOF(NORMAL)*4 + SIZEOF(POSITION)*6 );    DrawRangeElementsBaseVertex(TRIANGLES,0,6,6,UNSIGNED_INT,7,0);// THE BASE VERTEX IS 0, BECAUSE I SPECIFY THE EXACT OFFSET BY VERTEX POINTER  BUT THE ABOVE CODE DESCRIBED IN PSEUDO-CODE CAN NOT WORK. I DONT KNOW WHY, HOPE SOMEONE CAN TELL ME THE REASON,THANKS!   ;  Problem solved,  karwosts ,Thank you for replay   