GetSpriteRect Example (Dirty Rectangles / Selective Map Refreshing)

[kevin]

  GetSpriteRect Example (Dirty Rectangles / Selective Map Refreshing)

     This is a variation of the selective map refreshing examples, the main difference is that this version draws a sprite scene and uses the GetSpriteRect function to query the sprites bounding box volume.  This saves us have to manually query the sprites possibly rotated and scaled verts.    Not only that we can make the normally fixed cost of rendering a frame more efficient, since the display refresh only has to draw sections of the backdrop and not the whole thing.        
     

     Requires PlayBASIC V1.64O Beta 19 or higher

PlayBASIC Code: [Select]

   loadfont  "arial",1,16,0,8


   // -----------------------------------------------------------
   // Size the Map blocks we'll use.  
   // -----------------------------------------------------------
   constant TileWidth   =32
   constant TileHeight   =32

   // -----------------------------------------------------------
   // Make the Backdrop image.  This buffer is also used for the 'FX surface'
   // -----------------------------------------------------------
   BackDropFX =MakeBackdropImage()


   // -----------------------------------------------------------
   // Make a blob image to represent the sprites in the scene
   // -----------------------------------------------------------
   Blob= MakeBlobImage(64,64)


   // -----------------------------------------------------------
   // Define our RECT structure to hold the bounds of each sprite
   // -----------------------------------------------------------

    Type tRect
         x1,y1
         x2,y2
    EndType

   // -----------------------------------------------------------
   // Define a type to simulate some characters in the scene.
   // -----------------------------------------------------------
   Type tAlien
         Sprite
         speed#
         direction#
         Rect as tRect
   EndType

   // ------------------------------------------------------
   // Dim a list called Character to hold the objects
   // ------------------------------------------------------
   Dim Character as TAlien list


   // ------------------------------------------------------
   // Set the clip zone of the object
   // ------------------------------------------------------
   clipSize=64
   ViewportX1=-clipSize
   ViewportX2=GetSCreenWidth()+clipSize
   ViewportY1=-clipSize
   ViewportY2=GetSCreenHeight()+clipSize
   

   // ------------------------------------------------------
   // MAKE MAP / LEVEL / BLOCKS from our backdrop picture
   // ------------------------------------------------------

    Map,OriginalLevel,RefreshLevel=Make_Map_FRom_Image(BackDropFX)
    
     


   ;*=-----------------------------------------------------------------------------=*   
   ;         >> Main Loop <<
   ;*=-----------------------------------------------------------------------------=*   

    
    Screen=NewIMage(GetScreenWidth(),GetScreenHeight(),2)


   Do

         // Add new charcter to scene if the space key is being pressed         
         if Spacekey()  or  LastTime<Timer()

               LastTime=Timer()+50
               Add_Random_Character(Blob)

         endif         


         // Process and render to the objects in the character list
         RenderToImage Screen
         
         
         // Draw the refresh level to our FX image screen
         drawmap Map,RefreshLevel,0,0
         
         // reset the refresh level
         ClearLevel Map,RefreshLevel,0


         // Process our list of characters      
         For each Character()

               ThisSprite=Character.Sprite
               Speed#      =Character.speed#
               Angle#      =Character.direction#

               moveSprite ThisSprite,Cosradius(angle#,speed#),SinRadius(angle#,speed#)

               ; Check if the character is inside the screen ?
               if RectHitSprite(ViewportX1,ViewportY1,ViewportX2,ViewportY2,ThisSprite)=false
                     deleteSprite Sprite
                     Character=null
                     continue
               endif

               // Get the rect around this sprite... 
               if GetSpriteRect(ThisSprite,Character.Rect)
                  // Convert Pixels coordinates to Map Tile positions
                  x1=Character.Rect.x1/TileWidth
                  y1=Character.Rect.y1/TileHeight
                  x2=Character.Rect.x2/TileWidth
                  y2=Character.Rect.y2/TileHeight
                  CopyLevel   Map,OriginalLevel,x1,y1,x2+1,y2+1,Map,RefreshLevel,TilePad+x1,TilePad+y1
               endif
         Next
         
         
         // Draw the Sprite List to the FX buffer image
         DrawAllSprites


         // Direct rendering to the PB display
         rendertoscreen

         // Draw the current state of the Backdrop to the SCREEN
            Drawimage Screen,0,0,false

         // Draw the info to the screen for the viewer   
            text 0, 0,"Refresh %:"+CalcRefreshPercentage(Map,RefreshLevel)
            text 0,20,"Fps:"+str$(Fps())
         
         Sync
   loop   




;*=-----------------------------------------------------------------------------=*   
;                        >> Add Random Character <<
;*=-----------------------------------------------------------------------------=*   
;

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 Related Articles:

     * Selective Tile Map Refreshing