QueryWorldRegion

Items = QueryWorldRegion(ThisWorld, X1, Y1, X2, Y2, Address)

Parameters:     ThisWorld = The index of the world you wish to query     X1 = The Top Left X coordinate     Y1 = The Top Left Y coordinate     X2 = The Bottom Right X coordinate     Y2 = The Bottom Right Y coordinate     Address = The Address the query items should be written into

Returns:     Items = The Number of items within this region

QueryWorldRegion is an advanced command. It's purpose is to let the user get list of what captured graphic item are stored within a particular region within the world. While it's sounds simple enough, it's implementation can be a little clunky. So bare with me.       To query what's within at a particular region of a world, all we do is give QueryWorldRegion the world we wish to check, a rectangular region it should compare against and the address of where it should output the results.       QueryWorldRegion check each item bounding box. If an items bounding box overlaps your query region, then this item is considered to be within this zone. Even though that actually graphic item might well be just outside of it.       Now here's the the tricky part. The list of items QueryWorldRegion returns, will the index of the of that was captured. You can't actually access the captured item though. This means that user must keep track of the items that were captured and there positions in order to really make use of the results. Which is how the attached example works. FACTS:       * QueryWorldRegion expects to be passed the address of where you want the found items stored. It's recommended you use a bank for this. So when calling the QueryWorldRegion function would call the GetBankPtr function, which will get the address of your bank, and thus pass it to QueryWorldRegion. So it can store data directly in that memory       * QueryWorldRegion assumes the address you give it will be a piece of memory that is large enough to hold the results it might generate. If it's not, your program will most probably crash.       * QueryWorldRegion returns it's results as a list of integer values. If you've stored them within a bank it's recommended you use the PeekBankInt to retrieve them.

Example Source: Download This Example ; Convert the default font to a bitmap font   MakeBitmapFont 1,$ffffff          ; Create 2 variables that will be used as the worlds size   WorldWidth     =3000   WorldHeight     =3000    ; create a Camera (this camera will attach it self to the ; current surface, in this that example, current surface will ; be the Screen)   MyCamera=NewCamera()    ; Limit the cameras movement to the inside the world space   LimitCamera MyCamera,true   LimitCameraBounds MyCamera,0,0,WorldWidth+1,WorldHeight+1       Restart:    ; check if the world previously exists, if so, delete it   If GetWorldStatus(MyWorld) Then DeleteWorld MyWorld       ; Create world   MyWorld=NewWorld()    ; ReDirect All Drawing to be captured to world buffer #2   CaptureToWorld MyWorld       ; Create a list of Constants that will be used to ID the different gfx types ; that were captured into the world buffer   ACSet =0   Constant Gfx_Item_Dot           =AC(1)   Constant Gfx_Item_Line           =AC(1)   Constant Gfx_Item_Box           =AC(1)   Constant Gfx_Item_Circle      =AC(1)   Constant Gfx_Item_Shape      =AC(1)   Constant Gfx_Item_Max      =AC(1)    ; max size of a gfx item   Size=500    ; NUmber of gfx items to capture   Max_Gfx_Items=250       ; Define a type and array to hold the position/type information ; about each item.  Just so we can highlight them in this demo.      Type tObjectInfo      ItemType      Coords(4)      Radius      FillState      Colour      MediaIndex   EndType      Dim Items(Max_Gfx_Items) As tObjectInfo       ; Set the Capture Z Depth to 100   CaptureDepth 100    ; Capture the Gfx items   For lp=0 To Max_Gfx_Items          ; Random select a Item Type ot capture into the world buffer            ThisGFXitem =      Rnd(Gfx_Item_Max-1)          ; reset the coords      x=0:y=0      x2=x:y2=y      col               =RndRGB() And $7f7f7f      FillState     =Rnd(1)      radius=0      MediaIndex=0            Select ThisGfxItem                        Case Gfx_Item_Dot              X=Rnd(WorldWidth)              Y=Rnd(WorldHeight)                          ; draw the dot the world buffer              DotC X,Y,Col                        Case Gfx_Item_Line              X=Rnd(WorldWidth)              Y=Rnd(WorldHeight)                            X2=x+Rnd(size)              Y2=Y+Rnd(size)            ; draw the dot the world buffer              LineC X,Y,x2,y2,Col                        Case Gfx_Item_Box              X=Rnd(WorldWidth)              Y=Rnd(WorldHeight)                            X2=x+Rnd(size)              Y2=Y+Rnd(size)            ; draw the dot the world buffer              BoxC X,Y,x2,y2,fillstate,Col                        Case Gfx_Item_Circle              X=Rnd(WorldWidth)              Y=Rnd(WorldHeight)                            Radius=Rnd(100)            ; draw the dot the world buffer              CircleC X,Y,radius,fillstate,Col                                                    Case Gfx_Item_Shape              Radius=Rnd(100)              MediaIndex=GetFreeShape()              CreateConvexShape MediaIndex,Radius,RndRange(3,20)                            X=Rnd(WorldWidth)              Y=Rnd(WorldHeight)                          ; draw/capture the Shape the world buffer              DrawShape MediaIndex,X,Y,1                    EndSelect          ; Store the info about this ITem in array, so we can read it later            Items(lp).ItemType     =ThisGfxItem      Items(lp).Coords(1)     =x      Items(lp).Coords(2)     =y      Items(lp).Coords(3)     =x2      Items(lp).Coords(4)     =y2      Items(lp).Radius          =radius      Items(lp).FillState     =FillState      Items(lp).Colour          =Col      Items(lp).MediaIndex     =MediaIndex   Next    ; Partition The world up into 64 by 64 cells   PartitionWorld MyWorld,64    ; Tell PB to return to Immediate drawing mode   DrawGFXImmediate            Camx#=WorldWidth/2   Camy#=WorldHeight/2             ; ================================================= ; CReate a Memory bank.  This Bank is where we'll store the QueryWorldRegion results ; =================================================    ; Create the bank with plenty of space   CreateBank 1,1000          ; start of DO/Loop   Do          ; Tell PB to redirect all GFX drawing commands to the scene buffer      CaptureToScene          ; Clear the scene buffer      ClsScene                ;Move the Camera With Arrow Keys      CamSpeed#=5      If LeftKey() Then CamX#=CamX#-CamSpeed#      If RightKey() Then CamX#=CamX#+CamSpeed#      If UpKey() Then CamY#=CamY#-CamSpeed#      If DownKey() Then CamY#=CamY#+CamSpeed#                            ; Calc A region 200*200 around the current camera position            x1#=Camx#-100      y1#=Camy#-100      x2#=Camx#+100      y2#=Camy#+100          ; draw this region the user can see it      CaptureDepth 1      Box x1#,y1#,x2#,Y2#,0                ; Query World Region check the worlds parition buffer for a list of objects    ; that share this region.          ; The function returns the number of Items who's BOUNDING BOXES share    ; the same region.          ; NOTE:  Objects are returned in a pre-allocated memory buffer, function    ;        expected you to pass it a POINTER to this buffer.  So you    ;        actually get it write the valeus into an INTEGER array if you    ;        want also.  But that's not a easy for the user at this time..                  ItemsFound=QueryWorldRegion(MyWorld,x1#,y1#,x2#,y2#,GetBankPtr(1))            If ItemsFound>0                  CaptureDepth 10                  For lp=0 To (ItemsFound-1)                        GfxItem=PeekBankInt(1,lp*4)                        x     =Items(GfxItem).Coords(1)            y     =Items(GfxItem).Coords(2)            x2     =Items(GfxItem).Coords(3)            y2     =Items(GfxItem).Coords(4)                        Radius          =Items(GfxItem).Radius            FillState     =Items(GfxItem).FillState            MediaIndex     =Items(GfxItem).MediaIndex            Col               =RGBFade(Items(GfxItem).Colour,200)                        Select Items(GfxItem).ItemType                                    Case Gfx_Item_Dot                  ; draw the dot the world buffer                    DotC X,Y,Col                    CircleC x,y,3,0,RndRGB()                                    Case Gfx_Item_Line                  ; draw the dot the world buffer                    LineC X,Y,x2,y2,Col                    CircleC x,y,3,0,RndRGB()                    CircleC x2,y2,3,0,RndRGB()                                    Case Gfx_Item_Box                  ; draw the dot the world buffer                    BoxC X,Y,x2,y2,fillstate,Col                    CircleC x,y,3,0,RndRGB()                    CircleC x2,y2,3,0,RndRGB()                    CircleC x2,y,3,0,RndRGB()                    CircleC x,y2,3,0,RndRGB()                                    Case Gfx_Item_Circle                  ; draw the dot the world buffer                    CircleC X,Y,radius,fillstate,Col                                        CircleC x,y,2,0,RndRGB()                                                        Case Gfx_Item_Shape                    Ink Col                  ; draw/capture the Shape the world buffer                    DrawShape MediaIndex,X,Y,2                                EndSelect                      ; Store the info about this ITem          ;               Items(lp).ItemType=ThisGfxItem                     Next               EndIf                  PositionCamera MyCamera,CamX#-(GetScreenWidth()/2),Camy#-(GetScreenHeight()/2)            CaptureDepth 100      CameraGrabWorld MyCamera,MyWorld                ; draw the camera      DrawCamera MyCamera          ; show the fps rate and continue this loop      Text 0,0,FPS()      Text 0,10,itemsfound            If SpaceKey() Then Goto restart            Sync   Loop

Related Info:	CameraBasics | GetWorldClosestPoint | GetWorldElements | PartitionWorld | RayIntersectWorld | SpriteCollisionMode | WorldElementVisible :

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