Saturday, March 4, 2017

Monkey-X - Collision - Point vs Rectangle - code example

' From the book '2d game collision detection'
' point vs rectangle collision

Import mojo

' This is the collision class.
Class collision
    ' Collision function
    ' The point vs rectangle Collision
    Function point_rectangle_collide:Bool(p:vector2d,r:rectangle)
        Local left:Float = r.origin.x
        Local right:Float = left + r.size.x
        Local bottom:Float = r.origin.y
        Local top:Float = bottom + r.size.y        
        Return     left <= p.x And
                bottom <= p.y And
                p.x <= right And
                p.y <= top    
    End Function
End Class

Class vector2d
    ' x and y hold the position of the vector
    Field x:Int,y:Int
    Method New(x:Int,y:Int)
        Self.x = x
        Self.y = y
    End Method
End Class

Class rectangle
    ' origin is a vector that holds the x and y coordinates
    ' of the rectangle
    Field origin:vector2d
    ' size is a vector that holds the x(width) and 
    ' y(height) of the rectangle
    Field size:vector2d
    Method New(origin:vector2d,size:vector2d)
        Self.origin = origin
        Self.size = size
    End Method
    Method draw()
        ' x1,y1,w,h are used to hold the rectangle
        ' location and size.
        Local x1:Int=origin.x
        Local y1:Int=origin.y
        Local w:Int=size.x
        Local h:Int=size.y
        DrawRect x1,y1,w,h
    End Method
End Class

' col is the caller of the class collision. 
' we use it to use the collision methods.
Global col:collision = New collision

Class MyGame Extends App
    Field angle:Float
    Method OnCreate()
    End Method
    Method OnUpdate()
        If angle > 360 Then angle = 0  
    End Method
    Method OnRender()
        Cls 0,0,0 
        SetColor 255,255,255
        ' this is a point(vector) with the mouse coordinates
        Local point:vector2d = New vector2d(MouseX,MouseY)
        ' This is the rectangle
        Local origin:vector2d = New vector2d(320,200)
        Local size:vector2d = New vector2d(100,100)
        Local rect1:rectangle = New rectangle(origin,size)

        ' Here we test for collision
        If col.point_rectangle_collide(point,rect1)
            DrawText "Point vs Rectangle Collision",0,0
            DrawText "Point vs Rectangle NO Collision",0,0
        End If
        DrawText "Move the Mouse to test for Collision",DeviceWidth/2,0
    End Method
End Class

Function Main()
    New MyGame()
End Function

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