[SDL] Copy parts from surface to other surfaces

[dutchtux]

I want to copy a part from surface to antoher surface.
Can you tell me what function i must use with SDL and how it works.
A simple Example can be handy

[ShadowWolf]

SDL_BlitSurface(SDL_Surface *src, SDL_Rect *srcrect,
                          SDL_Surface *dst, SDL_Rect *dstrect)

you use the type SDL_rect and place the cordnets in there for the surface you want to copy from then use another SDL_RECT structor for the dest

i.e.
DIM img as SDL_surface ptr      '
DIM screen as SDL_surface ptr ' surfaces

'
' some code here to load a bmp or somthing into the surface's
'
dim  dest  as SDL_RECT
dim  source  as SDL_RECT
 
  source.x= 20
  source.y = 20
  source.h = 20
  source.w = 20

  dest.x = x;
  dest.y = y;
 
  SDL_BlitSurface(img, @source, screen, @dest);
 

'  i just did this of the top of my head so i'm not sure i got it right 'but i think i did
'

[dutchtux]

Problem Solved

Try to get it work but in someway it doesnt display the sprite

here is my subroutine:

Code:

sub putsprite(surfsource as SDL_Surface ptr, sprx, spry, sprnum)
   dim dest as SDL_Rect
   dim source as SDL_Rect
   
   source.x = sprnum * 32
   source.y = 0
   source.w = 32
   source.h = 32
     
   dest.x = sprx
   dest.y = spry  
   
   SDL_BlitSurface(surfsource, varptr(source), video, varptr(dest))
end sub

In some way it the SDL_blitsurface returns -1 I dont get that somewhere else but there is "varptr(source)"  is "0"

[Sterling Christensen]

Does putting byval on all the parameters help?

[dutchtux]

Well the problem was that "video" not a public sd_interface was.
So it needed to be added in the parameters or make it public.
I did the last one cause I forgot how it was in QB .
As long SDL_interface's arent public you cant access him in sub/functions

So the subroutine is now like this:

Code:

sub putsprite(surfsource as SDL_Surface ptr, video as SDL_Surface ptr, sprpos as SDL_Rect, sprnum)
   dim source as SDL_Rect
   
   source.x = int(sprnum * 32)
   source.y = 0  
   source.w = 32
   source.h = 32
 
   SDL_BlitSurface surfsource, varptr(source), video, varptr(sprpos)      
end sub

This way it will work.

[ShadowWolf]

Dim shared makes what ever your diming public.

[dutchtux]

It 's seems that if you make SDL_surface public you can't access it in subs
I got it like this:

Code:

   drawtext video, 64, 16, "This 1337 stuff is hot! Hope it got number support :)"

sub drawtext(video as SDL_Surface ptr, x, y, text as string)
   dim txtlen as integer
   dim charint as integer
   dim charrect as SDL_Rect
   
   txtlen = len(text)  
   for e% = 1 to txtlen
      charint = asc(mid$(text,e%,1))
      charrect.x = int((x + e%) * 16)
      charrect.y = int(y)
      if charint > 97 or charint < 122 then
         putsprite16 letterspr, video, charrect, charint - 98
      end if
      if charint > 65 or charint < 90 then
         putsprite16 letterspr, video, charrect, charint - 124
      end if
   next
end sub

sub putsprite16(surfsource as SDL_Surface ptr, video as SDL_Surface ptr, sprpos as SDL_Rect, sprnum)
   dim source as SDL_Rect
   
   source.x = int(sprnum * 16)
   source.y = 0  
   source.w = 16
   source.h = 16
 
   SDL_BlitSurface surfsource, varptr(source), video, varptr(sprpos)      

end sub

I dont know if it's a bug

[v3cz0r]

If you have an argument with the same name it will be used instead - QB quirk.

[dutchtux]

Well strange it doesnt draw it on the screen but gives as result 0
so it happens but in someway it doesnt getting draw on the screen.

the only thing that is shared is "letterspr"