proc gldisplay
     ;local jitter:QWORD, transx:DWORD, transy:DWORD, ftemp:DWORD, viewport[4]:DWORD <- doesn't work right
     local jitter:QWORD, viewport[4]:DWORD, transx:DWORD, transy:DWORD, ftemp:DWORD ;<- does work right

     invoke  glGetIntegerv, GL_VIEWPORT, addr viewport

     invoke  glClear, GL_ACCUM_BUFFER_BIT
    

;Well, if you wanted size optimization, you could change the macro to use
;PUSH/POP for registers instead of MOV. Something like this, I think:
macro static_rsp_prologue procname,flag,parmbytes,localbytes,reglist
 { local counter,loc,frame,current
   counter = 0
   irps reg, reglist \{ push reg
                        counter = counter+1 \}
   loc = (localbytes+7) and (not 7)
   if frame & (counter+loc shr 3+1) and 1
    loc = loc + 8
   end if
   framebytes@proc equ frame+loc
   if framebytes@proc
    sub rsp,framebytes@proc
   end if
   localbase@proc equ rsp+frame
   regsbase@proc equ rsp+frame+loc
   parmbase@proc equ rsp+frame+loc+counter*8+8
   current = 0
   current@frame equ current
   size@frame equ frame }

macro static_rsp_epilogue procname,flag,parmbytes,localbytes,reglist
 { if framebytes@proc
    add rsp,framebytes@proc
   end if
   irps reg, reglist \{ reverse pop reg \}
   retn }

macro static_rsp_close procname,flag,parmbytes,localbytes,reglist
 { size@frame = current@frame
   restore size@frame,current@frame }

prologue@proc equ static_rsp_prologue
epilogue@proc equ static_rsp_epilogue
close@proc equ static_rsp_close
;end extra code

stdcall fix fastcall


macro cinvoke proc,[arg]
 { common ccall [proc],arg }

macro ccall proc,[arg]
 { common vararg@fastcall = 1
          fastcall proc,arg
          vararg@fastcall = 0 }

vararg@fastcall = 0     

madmatt
The problem is that local variable definition macros do not provide any guarantees for the alignment. In your case they don't even have to do that. But a possibility for explicit alignment specification is desirable. Here's a bit of a discussion on that.

madmatt
Because the local variables are put onto the stack in the order you enumerate them. The stack at the beginning of the procedure is aligned to at least 16 bytes (because the calling convention demands that). So if you put one qword in front of viewport, than it will be aligned to 8 bytes only. And if you put 3 more dwords in front of it, than it will be aligned to 4 bytes only.