Rotate question

//===========================================================================
//Description:
// - A system that allows the user to create many shapes in a very simple and 
//customizable way. This is simply the core of the system. To draw more shapes
//you will have to import libraries.
//
//Author:
// - Flame_Phoenix
//
//Credits:
// - ThredNThrash, for the main idea and math formulas
// - BubleTech, for efficiency advices
// - Pyro and Anitarf for suggestions on how to improve
// - Veev, for fixing grammar
//
//@version 1.1.3
//===========================================================================
library SimpleShapes requires LinkedList
    
    struct Point 
        private real pointx
        private real pointy
        private real pointTang
        
        static method create takes real newX, real newY returns Point
            local Point this = Point.allocate()
            
            //setting members
            set .pointx = newX
            set .pointy = newY
            
            return this
        endmethod
        
        //Getters
        method operator x takes nothing returns real
            return .pointx
        endmethod
        
        method operator y takes nothing returns real
            return .pointy
        endmethod
        
        method operator tang takes nothing returns real
            return .pointTang
        endmethod
        
        //Setters
        method operator x= takes real newX returns nothing
            set .pointx = newX
        endmethod
        
        method operator y= takes real newY returns nothing
            set .pointy = newY
        endmethod
        
        method operator tang= takes real newTang returns nothing
            set .pointTang = newTang
        endmethod
    endstruct
    
    struct Shape
        List points
        
        static method create takes nothing returns Shape
            local Shape this = Shape.allocate()
            
            //create our list
            set .points = List.create()
            
            return this
        endmethod
        
        method onDestroy takes nothing returns nothing
            call .points.destroy()
        endmethod
    endstruct
    
endlibrary

//===========================================================================
//Description:
// - This library allows you to have an object called Line. It has two optional
//modules you can import to have extra features: xefxLineModule and 
//lightningLineModule.
//
//Requires:
// - SimpleShapes
//
//Methods you can use:
//  static method createLine takes real sX, real sY, real eX, real eY, real interval 
//returns Line
// - sX and sY and startX and startY where the Line begins. eX and eY stand for endX
//and endY respectively. The interval is the space between points.
//
//Members you can use:
//  real ANGLE - imagine that you want to move an object accross a line. This is the angle
//the object needs to have and it is in radians. To get the inverse of an angle just do
//ANGLE + bj_PI.
//
//Author:
// - Flame_Phoenix
//
//Credits:
// - Chobibo, for reporting major problems
//
//@version 1.2.1
//===========================================================================
library LineShape requires SimpleShapes

    struct Line extends Shape
        private real LINE_ANGLE // the tangent line in rads, useful to move projectiles
        private integer size
        private real dist
        
        implement optional XefxLineModule
        implement optional LightningLineModule
        
        static method createLine takes real sX, real sY, real eX, real eY, real interval returns Line
            local Line this = Line.allocate()
            
            //the distance of the line
            local real dx = sX - eX
            local real dy = sY - eY
            local real dist = SquareRoot(dx*dx + dy*dy) 
            
            //temporary variables that will allow us to create many points
            local integer i = 0
            
            //this is to make code easier to read in the loop
            local real x    
            local real y
            
            //this variables are for efficiency reasons
            local real xAng   
            local real yAng   
            set .size = R2I(dist / (interval ) )
            set .dist = dist
            //setting our members
            set .LINE_ANGLE = Atan2(eY - sY, eX - sX)
            
            set xAng = Cos(.LINE_ANGLE) 
            set yAng = Sin(.LINE_ANGLE)
            
            loop
                exitwhen(i == .size)
                
                //polar projection stuff
                set x = sX + ((i * dist) / .size) * xAng
                set y = sY + ((i * dist) / .size) * yAng
                
                call Link.createLast(.points, Point.create(x, y))
                
                set i = i + 1
            endloop
            
            return this
        endmethod
        
        //getter
        method operator ANGLE takes nothing returns real
            return .LINE_ANGLE
        endmethod
        
        stub method move takes real sX, real sY, real eX, real eY returns nothing
            //the distance of the line
            local real dx = sX - eX
            local real dy = sY - eY
            local real dist = SquareRoot(dx*dx + dy*dy) 
            
            //temporary variables that will allow us to create many points
            local integer i = 0
            
            //this is to make code easier to read in the loop
            local real x    
            local real y
            
            //this variables are for efficiency reasons
            local real xAng   
            local real yAng   
            
            //destroy the old list and create a new one with the new postitions
            call .points.destroy()
            set .points = List.create()
            
            //setting our members
            set .LINE_ANGLE = Atan2(eY - sY, eX - sX)
            
            set xAng = Cos(.LINE_ANGLE) 
            set yAng = Sin(.LINE_ANGLE)
            
            loop
                exitwhen(i == .size)
                
                //polar projection stuff
                set x = sX + ((i * dist) / .size) * xAng
                set y = sY + ((i * dist) / .size) * yAng
                
                call Link.createLast(.points, Point.create(x, y))
                
                set i = i + 1
            endloop
        endmethod
        
        stub method rotate takes real AngleDEG returns nothing
            local real lastX = Point(.points.last.data).x
            local real lastY = Point(.points.last.data).y
            local real rotX = lastX*Cos(AngleDEG*bj_DEGTORAD) + lastY*Cos(AngleDEG*bj_DEGTORAD + bj_PI/2)
            local real rotY = lastX*Sin(AngleDEG*bj_DEGTORAD) + lastY*Sin(AngleDEG*bj_DEGTORAD + bj_PI/2)
            
            call .move(Point(.points.first.data).x, Point(.points.first.data).y, rotX, rotY)
        endmethod

    endstruct
endlibrary

set newx=x*Cos(a)-y*Sin(a)
set newy=x*Sin(a)+y*Cos(a)

struct cross 
    Line l1
    Line l2
    stub method rotate takes real degs returns nothing
        call l1.rotate(degs)
        //same for l2
    endmethod
endstruct

set newx = x*Cos(a) + y*Cos(a + bj_PI/2)
set newy = x*Sin(a) + y*Sin(a + bj_PI/2)