Sprite to world alignment

[kevin]

This example uses the world and ray to world intersection features
in PB1.08 to help position sprites on sloped ground  with rough
alignment to the terrain.

  There's a few bugs,like really movement and aligment should be handed
together.  but ya get that :)

PlayBASIC Code: [Select]

Constant ShowVectors=True


; create a Blue Block to represent a character
Constant Height=64
Cls 255
Getimage 1,0,0,32,Height
preparefximage 1

; create the players sprite 
createsprite 1
spriteimage 1,1
spritedrawmode 1,2
centerspritehandle 1


; build a world with 
MyWOrld=BuildWorld()
 

; create the camera
CreateCamera 1

; start of Main DO/Loop
Do
; Set PB to Capture all drawing operation to the scene buffer
   Capturetoscene
   clsscene


; Let the user Control the Sprite left/right
   speed=5
   mx=0   
   if LeftKey() then mx=-speed
   if RightKey() then mx=speed
   movesprite 1,mx,0


   PositionSpriteOnGround(1,myWorld,4)

   AlignSpriteToGround(1,myWorld)


; position camera at the sprite position
   positioncamera 1,GetSpriteX(1)-GetScreenwidth()/2,GetSpriteY(1)-GetScreenHeight()/2


  ; draw the world/scene   
   Cameragrabworld 1,myworld
   drawallsprites
   DRawcamera 1   

   SYnc   
loop



Function PositionSpriteOnGround(ThisSprite,ThisWorld,Speed)
   ; get the sprites Position
   x=getspritex(ThisSprite)
   y=getspritey(ThisSprite)+speed

   newy=y

   For Xoffset=-8 to 8 step 8
   ; cast a ray from the center of sprite downwards
  Flag=Rayintersectworld(ThisWorld,x+Xoffset,y-(height/2),x+Xoffset,y+(height*2))

  line x+Xoffset,y-(height/2),x+Xoffset,y+(height*2)

   ; check if the ray hit the world(ground in this example)
  if Flag
     ;get the height of the ground at this point
     groundY=GetIntersecty#(0)
  ; reposition the sprite if it's Y was lower than the ground
     if (newy+(Height/2))=>GroundY then newy=groundY-((height/2)-1)
  endif
   next
   

  ; position the sprite after collision   
   positionsprite ThisSprite,x,newy   

EndFunction

   
; =============================================================================
;  This function calc's a rough approximation of this sprite to the ground. 
; =============================================================================


Function AlignSpriteToGround(ThisSprite,ThisWorld)
   Static OldAngle#

   ; get the sprites Position
   x=getspritex(ThisSprite)
   y=getspritey(ThisSprite)


   CurrentAngle#=GetSpriteAngle(ThisSprite)
;   CurrentAngle#=0
   GroundAngle#=0

; Project line from /through sprites base
;Calc points for LEFT Ray
   Left_rayx1#,Left_rayy1#=Rotate_Vertex(CurrentAngle#,-15,(height/2)*-1)
   Left_rayx2#,Left_rayy2#=Rotate_Vertex(CurrentAngle#,-15,(height*1.0))

   Left_rayx1#=Left_rayx1#+x
   Left_rayy1#=Left_rayy1#+y
   Left_rayx2#=Left_rayx2#+x
   Left_rayy2#=Left_rayy2#+y

  #if ShowVectors=true
  line Left_rayx1#,Left_rayy1#,Left_rayx2#,Left_rayy2#
   #endif
   
; cast a ray from the center of sprite downwards
   LeftFlag=Rayintersectworld(ThisWorld,Left_rayx1#,Left_rayy1#,Left_rayx2#,Left_rayy2#)

; check if the ray hit the world(ground in this example)
   if LeftFlag
    ;get point where the ray impact the ground (on the left side)
       LeftGroundX#=GetIntersectX#(0)
  LeftGroundY#=GetIntersectY#(0)
  LeftGroundNX#=GetnormalX#(0)
  LeftGroundNY#=GetnormalY#(0)
;  LeftDist#=getdistance2d(left_rayx1#,Left_rayy1#,LeftGroundX#,LeftGroundY#)

     #if ShowVectors=true
     x2#=LeftGroundX#+(LeftGroundNX#*50)
     y2#=LeftGroundY#+(LeftGroundNY#*50)
     line LeftGroundX#,LeftGroundY#,x2#,y2#
  #endif
   endif



;Calc points for LEFT Ray
   right_rayx1#,Right_rayy1#=Rotate_Vertex(CurrentAngle#,13,(height/2)*-1)
   Right_rayx2#,Right_rayy2#=Rotate_Vertex(CurrentAngle#,13,(height*1.0))

   right_rayx1#=right_rayx1#+x
   right_rayy1#=right_rayy1#+y
   right_rayx2#=right_rayx2#+x
   right_rayy2#=right_rayy2#+y


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[Draco9898]

Very nice, thanks alot