IDirect3DDevice9Ex::ComposeRects

DX9 vtable[120] → HRESULT

IDirect3DDevice9Ex::ComposeRects is a method of the COM interface IDirect3DDevice9Ex in Direct3D 9. Its function pointer sits at vtable index 120 — the zero-based slot in that interface's virtual method table, counted from QueryInterface and including every entry inherited from a base interface. It takes 8 parameters (src_surface, dst_surface, src_descs, rect_count, dst_descs, operation, offset_x, offset_y) and returns HRESULT.

COM methods are reached through that table rather than by an exported name, so the slot index is what a wrapper, an interface hook or a disassembly listing has to resolve against. The parameter order and types below are the ones this interface declares.