QuadOccludeMap

State = QuadOccludeMap(ThisMap, TheLevel, X1, Y1, X2, Y2, X3, Y3, X4, Y4)

Parameters:     ThisMap = The Index of the map you wish to occlude     TheLevel = The level within the map     X1 = The X coordinate of Vertex 1     Y1 = The Y coordinate of Vertex 1     X2 = The X coordinate of Vertex 2     Y2 = The Y coordinate of Vertex 2     X3 = The X coordinate of Vertex 3     Y3 = The Y coordinate of Vertex 3     X4 = The X coordinate of Vertex 4     Y4 = The Y coordinate of Vertex 4

Returns:     State = The status of occlusion function

The QuadOccludeMap() function checks if a Quad (4 sided polygon) region is occluding the equivalent area within a map level. The QuadOccludeMap function will clear this area on the selected map level, this helps reduce the amount of overdraw your game is performing. So the map occlusion commands help us even out the amount of rendering time our game is doing each update.       For example, If we imagine a game scene with 2 or more map layers, then normally we'd draw them all over each other, regardless of what is actually visible in screen. So with three layers we're potentially drawing every pixel on the screen three times.       With modern hardware, this may not be such of big deal (assuming a medium screen resolution), but what if you want your games to run older systems, or you just want to squeeze every drop of rendering performance you can ? - Well, then it's worth seeing if we can cull out any of the redundant background drawing by removing anything in the background that's being occluded by foreground graphics.       We could do this by previously calculating the hard regions of the foreground. These might be stored in list for example, then before rendering the back layers, we mask those layers with out hard foreground region, using some of the map occlusion commands. This is remove any blocks in those that layers that would have been being drawn, but never visible to the player. You could do the same thing with sprites too. It's really up to you.       The key to occlusion, is that when we remove the hidden background elements, this area has to be covered with something solid in the foreground. It doesn't work if the foreground area is translucent, this breaks the illusion, as the player can see both the foreground and the missing background segment.       However, we don't want to get too excited and try to implement too much occlusion, As with all optimizations, there's a fine line between getting meaningful rendering performance gain, and losing that potential gain by adding bunch of clunky calculations in their place. So remember, we're trying to remove work from our game, not add more to it. FACTS:       * QuadOccludeMap will alter the level if any block is clearly within the bounds the commands region. If up to the user to restore this. See CopyLevel, CloneLevel

Example Source: Download This Example ;     ----------------------------------------------- ;           --------->> SET UP <<------------ ;     -----------------------------------------------         SetFPS 100      Method=1   RectWidth=250   RectHeight=200   Angle#=45      Dim vertx#(4)   Dim verty#(4)       ; create the random map from some circles   Map,OriginalLevel=Build_Random_Map(32,32)    ; request a free index of the level in this map   Level=GetFreeMapLevel(Map)    ; make a backdrop picture   BackDrop=NewImage(800,600)   RenderToImage Backdrop   c1=RndRGB()   c2=RndRGB()   ShadeBox 0,0,800,600,c1,c1,c2,c2   RenderToScreen       ; create a camera to view the scene with   Cam=NewCamera()   CameraCls Cam,off             ;     ------------------------------------------------ ;      --------->> MAIN LOOP OF PROGRAM <<---------- ;     ------------------------------------------------         Do          ; Get the camera current position      CamX=GetCameraX(cam)      CamY=GetCameraY(cam)          ; Get the mouse position      MX=MouseX()+CamX      MY=MouseY()+CamY          ; Check if the Left Mouse is pressed ?      If LeftMouseButton()         RectWidth=Mod(RectWidth+1,400)      EndIf          ; Check if the Right Mouse is pressed ?      If RightMouseButton()         RectHeight=Mod(RectHeight+1,400)      EndIf                ; Check if the Middle Mouse Button is pressed ?      If MidMouseButton()         Angle#=WrapAngle(Angle#,1)      EndIf          ; Restore the Level to it's original state      CloneLevel Map,OriginalLevel,Map,Level                ; tell PB to capture the following drawing commands      CaptureToScene          ; clear the scene buffer so it's empty      ClsScene                        Collision,Method$=DRawQuad(Map,Level,MX,MY,RectWidth,RectHeight,Angle#,Method)                      ; set the capture depth of the next item to a depth of    ; 100 units      CaptureDepth 100      DrawImage BackDrop,CamX,CamY,false          ; draw the map level      CaptureDepth 10      DrawMap map,Level,0,0                        CaptureDepth 5                ; Test if the Circle Hits the Map blocks & clear them      Collision=CircleOccludeMap(Map,Level,mx,my,radius)                            ; draw the Circle at this depth      CircleC Mx,My,Radius,Filled,$ffffff      CircleC Mx,My,Radius-1,false,$ffffff                ; draw the scene with this camera      DrawCamera cam                ; Check if the Space key was pressed      If SpaceKey()       ; if so, change the collision method         Method=1-Method         FlushKeys      EndIf          ; check if the ENTER key was pressed      If EnterKey()       ; If so, toggle Debug mode on the map         MapDebug Map,1-GetMapDebug(Map)         FlushKeys      EndIf                            ; check if the users wanted to move the camera      If LeftKey()  Then     MoveCamera Cam,-2,0      If RightKey() Then     MoveCamera Cam,2,0      If UpKey()    Then     MoveCamera Cam,0,-2      If DownKey()  Then     MoveCamera Cam,0,2            SetCursor 0,0      Ink $ffffff      Print "Press SPACE to toggle solid/outline"      Print "Mouse Buttons To Change Size"      Print "Method: "+Method$      Sync   Loop                ;     ------------------------------------------------- ;       ------>> Draw Polygon With Occlusion <<------- ;     -------------------------------------------------       Psub DRawQuad(ThisMap,ThisLevel,X,Y,Width,Height,Angle#,Method)         vertx#(0)=(Width/-2.0)   verty#(0)=(Height/-2.0)      vertx#(1)=(Width/2.0)   verty#(1)=(Height/-2.0)      vertx#(2)=(Width/2.0)   verty#(2)=(Height/2.0)      vertx#(3)=(Width/-2.0)   verty#(3)=(Height/2.0)      ca#=Cos(angle#)   sa#=Sin(angle#)      For lp=0 To 3      xpos#=     vertx#(lp)      ypos#=     verty#(lp)      vertx#(lp)=Floor(x+((ca#*xpos#)-(sa#*ypos#)))      vertY#(lp)=Floor(y+((ca#*ypos#)+(sa#*xpos#)))   Next               CaptureDepth 5      Select Method       Case 0           Collision=TriangleOccludeMap(ThisMap,ThisLevel,vertx#(0),vertY#(0),vertx#(1),vertY#(1),vertx#(2),vertY#(2) )           Collision+=TriangleOccludeMap(ThisMap,ThisLevel,vertx#(0),vertY#(0),vertx#(2),vertY#(2),vertx#(3),vertY#(3) )           Name$="TriangleOccludeMap"       Case 1           Collision=QuadOccludeMap(ThisMap,ThisLevel,vertx#(0),vertY#(0),vertx#(1),vertY#(1),vertx#(2),vertY#(2),vertx#(3),vertY#(3) )           Name$="QuadOccludeMap"              EndSelect    ; draw the outline in lines   Line vertx#(0),vertY#(0),vertx#(1),vertY#(1)   Line vertx#(1),vertY#(1),vertx#(2),vertY#(2)   Line vertx#(2),vertY#(2),vertx#(3),vertY#(3)   Line vertx#(3),vertY#(3),vertx#(0),vertY#(0)         If Method<1      Line vertx#(0),vertY#(0),vertx#(2),vertY#(2)   EndIf    EndPsub Collision,Name$             ;     ------------------------------------------------- ;      --------->> Build Random Map Scene <<--------- ;     -------------------------------------------------       Function Build_Random_Map(BlockWidth,BlockHeight)      BackdropColour=$008f00      screen=NewFXImage(2400,1600)   RenderToImage screen   Cls  BackdropColour   CircleC 800,400,400,true,$8f8f8f   CircleC 1700,400,400,true,$0f8faf      For lp=0 To 200      x=Rnd(2400)      y=Rnd(1600)      rx=RndRange(50,150)      ry=RndRange(10,50)      EllipseC x,y,rx,ry,true, BackdropColour   Next            Map=NewMap(50)    ; Create 1024 FX BLocks for this map   CreateMapGFX  Map,BlockWidth,BlockHeight,1024,_   BackdropColour,2      BlocksX=GetSurfaceWidth()/BlockWidth   BlocksY=GetSurfaceHeight()/BlockWidth      Level=NewLevel(Map,BlocksX,BlocksY)   LevelTransparent Map,Level,0   GetMapBlk Map,Tile,0,0      Tile=1   For ylp=0 To GetLevelHeight(map,level)-1      Ypos=ylp*BlockHeight      If Ypos+BlockHeight<=GetSurfaceHeight()         For xlp=0 To GetLevelWidth(map,level)-1            Xpos=xlp*BlockWidth            GetMapBlk Map,Tile,Xpos,ypos                        If GetMapBlockTransparent(Map,Tile)>-1               PokeLevelTile Map,Level,xlp,ylp,tile               tile++            EndIf            If Tile=>GetMapBlocks(Map)               ExitFor ylp            EndIf         Next      EndIf   Next      RenderToScreen    ; Turn Debug Map for this map   MapDebug Map,on    EndFunction Map,Level

Related Info:	CircleOccludeMap | EllipseOccludeMap | RectOccludeMap | TriangleOccludeMap :

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