LineHitSpritePixels - Learn To Code - PlayBASIC Documentation

LineHitSpritePixels

CollisionState = LineHitSpritePixels(X1, Y1, X2, Y2, SpriteIndex, Accuracy#)

Parameters:

    X1 = The Starting X coordinate of the line
    Y1 = The starting Y coordinate of the line
    X2 = The ending X coordinate of the line
    Y2 = The ending Y coordinate of the line
    SpriteIndex = The Sprite to check for collision against
    Accuracy# = The level of accuracy that should be used.

Returns:

CollisionState = The result of the collision query (0= No collision ,1 = Collision)

      The LineHitSpritePixels function detects if a collision occurs between a line and any pixel within a sprite.

Example Accuracy Values
      0.25 = Reduce collision accuracy to 25%
      0.50 = Reduce collision accuracy to 50%
      0.75 = Reduce collision accuracy to 75%
      1.00 = Set collision accuracy to 100%
      2.00 = Set collision accuracy to 200%

FACTS:

      * Note: LineHitSpritePixels does not return the first impact, just that an impact has occured

      * The Accuracy parameter allows the user to fine tune the quality of the pixel level sprite collisions. Generally speaking the lower the quality the faster the comparison. On the flip side the higher the quality the more accurate, but slower the comparison. It's up to the user to choose an accuracy level that is appropriate for your images and the performance of your game.

      * Pixels level collisions ignore the sprites transparent colour.

      * Also see SpriteCollisionMode

Mini Tutorial:

This example creates a random image, creates 10 randomly positioned sprites on the screen using this image. The main loop rotates the sprites while scans them for collisions using LineHitSpritePixels

; Clear the screen to black
  Cls RGB(0,0,0)


; Make an image with circles on it
  For lp =0 To 25
     CircleC Rnd(100),Rnd(100),RndRange(2,10),1,RndRGB()
  Next
  GetImage 1,0,0,100,100
  PrepareFXImage 1




; Make 10 sprites
  For spr=1 To 10

   ; position the sprite randomly on the screen
     x=Rnd(GetScreenWidth())
     y=Rnd(GetScreenHeight())

   ; Create the sprite using image #1
     Spr=NewSprite(x,y,1)

   ; center the sprite
     CenterSpriteHandle spr

  Next



  Do
     Cls RGB(0,0,0)

   ; Check if the mouse  is over a sprite
     mx#=MouseX()
     my#=MouseY()

   ; Randomly create end point of the line
     If SpaceKey() Or FirstRun=0
        x2#=Rnd(800)
        y2#=Rnd(600)
        firstrun=1
     EndIf

   ; Draw the test triangle
     LineC mx#,my#,x2#,y2#,RGB(255,255,255)

   ; start for/next loop from 1 to 10
     For spr=1 To 10

      ; Turn this sprite
        TurnSprite spr,0.25

      ; Check if our test line hits any pixels in this sprite
        If LineHitSpritePixels(mx#,my#,x2#,y2#,spr,1)=true
         ; Flash the sprite if there's a collison
           SpriteDrawMode Spr,2+4096
        Else
         ; Set it's draw mode to just rotated
           SpriteDrawMode Spr,2
        EndIf
     Next

     DrawAllSprites

     Sync
  Loop


Related Info:	CircleHitSprite \| EllipseHitSpritePixels \| PointHitSprite \| PointHitSpritePixels \| QuadHitSprite \| QuadHitSpritePixels \| RayHitSprite \| RectHitSprite \| RectHitSpritePixels \| ShapeHitSprite \| SpriteCollisionMode \| SpriteHit \| SpritesOverlap \| TriangleHitSpritePixels :