Synced with 2.3.

70 files changed, 627 insertions, 0 deletions

diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/app/ball.rb b/samples/04_physics_and_collisions/08_bouncing_on_collision/app/ball.rb
new file mode 100644
index 0000000..80b61e3
--- /dev/null
+++ b/samples/04_physics_and_collisions/08_bouncing_on_collision/app/ball.rb
@@ -0,0 +1,87 @@
+GRAVITY = -0.08
+
+class Ball
+    attr_accessor :velocity, :center, :radius, :collision_enabled
+
+    def initialize args
+        #Start the ball in the top center
+        #@x = args.grid.w / 2
+        #@y = args.grid.h - 20
+
+        @velocity = {x: 0, y: 0}
+        #@width =  20
+        #@height = @width
+        @radius = 20.0 / 2.0
+        @center = {x: (args.grid.w / 2), y: (args.grid.h)}
+
+        #@left_wall = (args.state.board_width + args.grid.w / 8)
+        #@right_wall = @left_wall + args.state.board_width
+        @left_wall = 0
+        @right_wall = $args.grid.right
+
+        @max_velocity = 7
+        @collision_enabled = true
+    end
+
+    #Move the ball according to its velocity
+    def update args
+      @center.x += @velocity.x
+      @center.y += @velocity.y
+      @velocity.y += GRAVITY
+
+      alpha = 0.2
+      if @center.y-@radius <= 0
+        @velocity.y  = (@velocity.y.abs*0.7).abs
+        @velocity.x  = (@velocity.x.abs*0.9).abs * ((@velocity.x < 0) ? -1 : 1)
+
+        if @velocity.y.abs() < alpha
+          @velocity.y=0
+        end
+        if @velocity.x.abs() < alpha
+          @velocity.x=0
+        end
+      end
+
+      if @center.x > args.grid.right+@radius*2
+        @center.x = 0-@radius
+      elsif @center.x< 0-@radius*2
+        @center.x = args.grid.right + @radius
+      end
+    end
+
+    def wallBounds args
+        #if @x < @left_wall || @x + @width > @right_wall
+            #@velocity.x *= -1.1
+            #if @velocity.x > @max_velocity
+                #@velocity.x = @max_velocity
+            #elsif @velocity.x < @max_velocity * -1
+                #@velocity.x = @max_velocity * -1
+            #end
+        #end
+        #if @y < 0 || @y + @height > args.grid.h
+            #@velocity.y *= -1.1
+            #if @velocity.y > @max_velocity
+                #@velocity.y = @max_velocity
+            #elsif @velocity.y < @max_velocity * -1
+                #@velocity.y = @max_velocity * -1
+            #end
+        #end
+    end
+
+    #render the ball to the screen
+    def draw args
+        #args.outputs.solids << [@x, @y, @width, @height, 255, 255, 0];
+        args.outputs.sprites << [
+          @center.x-@radius,
+          @center.y-@radius,
+          @radius*2,
+          @radius*2,
+          "sprites/circle-white.png",
+          0,
+          255,
+          255,    #r
+          0,    #g
+          255   #b
+        ]
+    end
+  end
diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/app/block.rb b/samples/04_physics_and_collisions/08_bouncing_on_collision/app/block.rb
new file mode 100644
index 0000000..9254ee4
--- /dev/null
+++ b/samples/04_physics_and_collisions/08_bouncing_on_collision/app/block.rb
@@ -0,0 +1,159 @@
+DEGREES_TO_RADIANS = Math::PI / 180
+
+class Block 
+  def initialize(x, y, block_size, rotation)
+    @x = x
+    @y = y 
+    @block_size = block_size
+    @rotation = rotation
+
+    #The repel velocity?
+    @velocity = {x: 2, y: 0}        
+
+    horizontal_offset = (3 * block_size) * Math.cos(rotation * DEGREES_TO_RADIANS)
+    vertical_offset = block_size * Math.sin(rotation * DEGREES_TO_RADIANS)
+
+    if rotation >= 0
+      theta = 90 - rotation
+      #The line doesn't visually line up exactly with the edge of the sprite, so artificially move it a bit
+      modifier = 5
+      x_offset = modifier * Math.cos(theta * DEGREES_TO_RADIANS)
+      y_offset = modifier * Math.sin(theta * DEGREES_TO_RADIANS)
+      @x1 = @x - x_offset
+      @y1 = @y + y_offset
+      @x2 = @x1 + horizontal_offset
+      @y2 = @y1 + (vertical_offset * 3)
+
+      @imaginary_line = [ @x1, @y1, @x2, @y2 ]
+    else
+      theta = 90 + rotation
+      x_offset = @block_size * Math.cos(theta * DEGREES_TO_RADIANS)
+      y_offset = @block_size * Math.sin(theta * DEGREES_TO_RADIANS)
+      @x1 = @x + x_offset
+      @y1 = @y + y_offset + 19
+      @x2 = @x1 + horizontal_offset
+      @y2 = @y1 + (vertical_offset * 3)
+
+      @imaginary_line = [ @x1, @y1, @x2, @y2 ]
+    end
+    
+  end
+
+  def draw args
+    args.outputs.sprites << [
+      @x,
+      @y,
+      @block_size*3,
+      @block_size,
+      "sprites/square-green.png",
+      @rotation
+    ]
+
+    args.outputs.lines << @imaginary_line
+    args.outputs.solids << @debug_shape
+  end
+
+  def multiply_matricies
+  end
+
+  def calc args
+    if collision? args
+        collide args
+    end
+  end
+
+  #Determine if the ball and block are touching
+  def collision? args
+    #The minimum area enclosed by the center of the ball and the 2 corners of the block
+    #If the area ever drops below this value, we know there is a collision
+    min_area = ((@block_size * 3) * args.state.ball.radius) / 2
+
+    #https://www.mathopenref.com/coordtrianglearea.html
+    ax = @x1
+    ay = @y1
+    bx = @x2
+    by = @y2
+    cx = args.state.ball.center.x
+    cy = args.state.ball.center.y
+
+    current_area = (ax*(by-cy)+bx*(cy-ay)+cx*(ay-by))/2
+
+    collision = false
+    if @rotation >= 0
+      if (current_area < min_area && 
+        current_area > 0 &&
+        args.state.ball.center.y > @y1 &&
+        args.state.ball.center.x < @x2)
+
+        collision = true
+      end
+    else
+      if (current_area < min_area && 
+        current_area > 0 &&
+        args.state.ball.center.y > @y2 &&
+        args.state.ball.center.x > @x1)
+
+      collision = true
+      end
+    end
+    
+    return collision
+  end
+
+  def collide args
+    #Slope of the block
+    slope = (@y2 - @y1) / (@x2 - @x1)
+
+    #Create a unit vector and tilt it (@rotation) number of degrees
+    x = -Math.cos(@rotation * DEGREES_TO_RADIANS)
+    y = Math.sin(@rotation * DEGREES_TO_RADIANS)
+
+    #Find the vector that is perpendicular to the slope
+    perpVect = { x: x, y: y }
+    mag  = (perpVect.x**2 + perpVect.y**2)**0.5                                 # find the magniude of the perpVect
+    perpVect = {x: perpVect.x/(mag), y: perpVect.y/(mag)}                       # divide the perpVect by the magniude to make it a unit vector
+
+    previousPosition = {                                                        # calculate an ESTIMATE of the previousPosition of the ball
+      x:args.state.ball.center.x-args.state.ball.velocity.x,
+      y:args.state.ball.center.y-args.state.ball.velocity.y
+    }
+    
+    velocityMag = (args.state.ball.velocity.x**2 + args.state.ball.velocity.y**2)**0.5 # the current velocity magnitude of the ball
+    theta_ball = Math.atan2(args.state.ball.velocity.y, args.state.ball.velocity.x)         #the angle of the ball's velocity
+    theta_repel = (180 * DEGREES_TO_RADIANS) - theta_ball + (@rotation * DEGREES_TO_RADIANS)
+
+    fbx = velocityMag * Math.cos(theta_ball)                                    #the x component of the ball's velocity
+    fby = velocityMag * Math.sin(theta_ball)                                    #the y component of the ball's velocity
+
+    frx = velocityMag * Math.cos(theta_repel)                                       #the x component of the repel's velocity | magnitude is set to twice of fbx
+    fry = velocityMag * Math.sin(theta_repel)                                       #the y component of the repel's velocity | magnitude is set to twice of fby
+
+    args.state.display_value = velocityMag
+    fsumx = fbx+frx                                                             #sum of x forces
+    fsumy = fby+fry                                                             #sum of y forces
+    fr = velocityMag                                                            #fr is the resulting magnitude
+    thetaNew = Math.atan2(fsumy, fsumx)                                         #thetaNew is the resulting angle
+
+    xnew = fr*Math.cos(thetaNew)                                                #resulting x velocity
+    ynew = fr*Math.sin(thetaNew)                                                #resulting y velocity
+
+    dampener = 0.3
+    ynew *= dampener * 0.5
+    
+    #If the bounce is very low, that means the ball is rolling and we don't want to dampenen the X velocity
+    if ynew > -0.1
+      xnew *= dampener
+    end
+
+    #Add the sine component of gravity back in (X component)
+    gravity_x = 4 * Math.sin(@rotation * DEGREES_TO_RADIANS)
+    xnew += gravity_x
+  
+    args.state.ball.velocity.x = -xnew
+    args.state.ball.velocity.y = -ynew
+
+    #Set the position of the ball to the previous position so it doesn't warp throught the block
+    args.state.ball.center.x = previousPosition.x
+    args.state.ball.center.y = previousPosition.y
+  end
+end
diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/app/cannon.rb b/samples/04_physics_and_collisions/08_bouncing_on_collision/app/cannon.rb
new file mode 100644
index 0000000..4df68fe
--- /dev/null
+++ b/samples/04_physics_and_collisions/08_bouncing_on_collision/app/cannon.rb
@@ -0,0 +1,20 @@
+class Cannon
+  def initialize args
+    @pointA = {x: args.grid.right/2,y: args.grid.top}
+    @pointB = {x: args.inputs.mouse.x, y: args.inputs.mouse.y}
+  end
+  def update args
+    activeBall = args.state.ball
+    @pointB = {x: args.inputs.mouse.x, y: args.inputs.mouse.y}
+
+    if args.inputs.mouse.click
+      alpha = 0.01
+      activeBall.velocity.y = (@pointB.y - @pointA.y) * alpha
+      activeBall.velocity.x = (@pointB.x - @pointA.x) * alpha
+      activeBall.center = {x: (args.grid.w / 2), y: (args.grid.h)}
+    end
+  end
+  def render args
+    args.outputs.lines << [@pointA.x, @pointA.y, @pointB.x, @pointB.y]
+  end
+end
diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/app/main.rb b/samples/04_physics_and_collisions/08_bouncing_on_collision/app/main.rb
new file mode 100644
index 0000000..f5883ad
--- /dev/null
+++ b/samples/04_physics_and_collisions/08_bouncing_on_collision/app/main.rb
@@ -0,0 +1,117 @@
+INFINITY= 10**10
+
+require 'app/vector2d.rb'
+require 'app/peg.rb'
+require 'app/block.rb'
+require 'app/ball.rb'
+require 'app/cannon.rb'
+
+
+#Method to init default values
+def defaults args
+  args.state.pegs ||= []
+  args.state.blocks ||= []
+  args.state.cannon ||= Cannon.new args
+  args.state.ball ||= Ball.new args
+  args.state.horizontal_offset ||= 0
+  init_pegs args
+  init_blocks args
+
+  args.state.display_value ||= "test"
+end
+
+begin :default_methods
+  def init_pegs args
+    num_horizontal_pegs = 14
+    num_rows = 5
+
+    return unless args.state.pegs.count < num_rows * num_horizontal_pegs
+
+    block_size = 32
+    block_spacing = 50
+    total_width = num_horizontal_pegs * (block_size + block_spacing)
+    starting_offset = (args.grid.w - total_width) / 2 + block_size
+
+    for i in (0...num_rows)
+      for j in (0...num_horizontal_pegs)
+        row_offset = 0
+        if i % 2 == 0
+          row_offset = 20
+        else
+          row_offset = -20
+        end
+        args.state.pegs.append(Peg.new(j * (block_size+block_spacing) + starting_offset + row_offset, (args.grid.h - block_size * 2) - (i * block_size * 2)-90, block_size))
+      end
+    end
+
+  end
+
+  def init_blocks args
+    return unless args.state.blocks.count < 10
+
+    #Sprites are rotated in degrees, but the Ruby math functions work on radians
+    radians_to_degrees = Math::PI / 180
+
+    block_size = 25
+    #Rotation angle (in degrees) of the blocks
+    rotation = 30
+    vertical_offset = block_size * Math.sin(rotation * radians_to_degrees)
+    horizontal_offset = (3 * block_size) * Math.cos(rotation * radians_to_degrees)
+    center = args.grid.w / 2
+
+    for i in (0...5)
+      #Create a ramp of blocks. Not going to be perfect because of the float to integer conversion and anisotropic to isotropic coversion
+      args.state.blocks.append(Block.new((center + 100 + (i * horizontal_offset)).to_i, 100 + (vertical_offset * i) + (i * block_size), block_size, rotation))
+      args.state.blocks.append(Block.new((center - 100 - (i * horizontal_offset)).to_i, 100 + (vertical_offset * i) + (i * block_size), block_size, -rotation))
+    end
+  end
+end
+
+#Render loop
+def render args
+  args.outputs.borders << args.state.game_area
+  render_pegs args
+  render_blocks args
+  args.state.cannon.render args
+  args.state.ball.draw args
+end
+
+begin :render_methods
+  #Draw the pegs in a grid pattern
+  def render_pegs args
+    args.state.pegs.each do |peg|
+      peg.draw args
+    end
+  end
+
+  def render_blocks args
+    args.state.blocks.each do |block|
+      block.draw args
+    end
+  end
+
+end
+
+#Calls all methods necessary for performing calculations
+def calc args
+  args.state.pegs.each do |peg|
+    peg.calc args
+  end
+
+  args.state.blocks.each do |block|
+    block.calc args
+  end
+
+  args.state.ball.update args
+  args.state.cannon.update args
+end
+
+begin :calc_methods
+
+end
+
+def tick args
+  defaults args
+  render args
+  calc args
+end
diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/app/peg.rb b/samples/04_physics_and_collisions/08_bouncing_on_collision/app/peg.rb
new file mode 100644
index 0000000..52045de
--- /dev/null
+++ b/samples/04_physics_and_collisions/08_bouncing_on_collision/app/peg.rb
@@ -0,0 +1,182 @@
+class Peg
+  def initialize(x, y, block_size)
+    @x = x                    # x cordinate of the LEFT side of the peg
+    @y = y                    # y cordinate of the RIGHT side of the peg
+    @block_size = block_size  # diameter of the peg
+
+    @radius = @block_size/2.0 # radius of the peg
+    @center = {               # cordinatees of the CENTER of the peg
+      x: @x+@block_size/2.0,
+      y: @y+@block_size/2.0
+    }
+
+    @r = 255 # color of the peg
+    @g = 0
+    @b = 0
+
+    @velocity = {x: 2, y: 0}
+  end
+
+  def draw args
+    args.outputs.sprites << [ # draw the peg according to the @x, @y, @radius, and the RGB
+      @x,
+      @y,
+      @radius*2.0,
+      @radius*2.0,
+      "sprites/circle-white.png",
+      0,
+      255,
+      @r,    #r
+      @g,    #g
+      @b   #b
+    ]
+  end
+
+
+  def calc args
+    if collisionWithBounce? args # if the is a collision with the bouncing ball
+      collide args
+      @r = 0
+      @b = 0
+      @g = 255
+    else
+    end
+  end
+
+
+  # do two circles (the ball and this peg) intersect
+  def collisionWithBounce? args
+    squareDistance = (  # the squared distance between the ball's center and this peg's center
+      (args.state.ball.center.x - @center.x) ** 2.0 +
+      (args.state.ball.center.y - @center.y) ** 2.0
+    )
+    radiusSum = (  # the sum of the radius squared of the this peg and the ball
+      (args.state.ball.radius + @radius) ** 2.0
+    )
+    # if the squareDistance is less or equal to radiusSum, then there is a radial intersection between the ball and this peg
+    return (squareDistance <= radiusSum)
+  end
+
+  # ! The following links explain the getRepelMagnitude function !
+  # https://raw.githubusercontent.com/DragonRuby/dragonruby-game-toolkit-physics/master/docs/docImages/LinearCollider_4.png
+  # https://raw.githubusercontent.com/DragonRuby/dragonruby-game-toolkit-physics/master/docs/docImages/LinearCollider_5.png
+  # https://github.com/DragonRuby/dragonruby-game-toolkit-physics/blob/master/docs/LinearCollider.md
+  def getRepelMagnitude (args, fbx, fby, vrx, vry, ballMag)
+    a = fbx ; b = vrx ; c = fby
+    d = vry ; e = ballMag
+    if b**2 + d**2 == 0
+      #unexpected
+    end
+
+    x1 = (-a*b+-c*d + (e**2 * b**2 - b**2 * c**2 + 2*a*b*c*d + e**2 + d**2 - a**2 * d**2)**0.5)/(b**2 + d**2)
+    x2 = -((a*b + c*d + (e**2 * b**2 - b**2 * c**2 + 2*a*b*c*d + e**2 * d**2 - a**2 * d**2)**0.5)/(b**2 + d**2))
+
+    err = 0.00001
+    o = ((fbx + x1*vrx)**2 + (fby + x1*vry)**2 ) ** 0.5
+    p = ((fbx + x2*vrx)**2 + (fby + x2*vry)**2 ) ** 0.5
+    r = 0
+
+    if (ballMag >= o-err and ballMag <= o+err)
+      r = x1
+    elsif (ballMag >= p-err and ballMag <= p+err)
+      r = x2
+    else
+      #unexpected
+    end
+
+    if (args.state.ball.center.x > @center.x)
+      return x2*-1
+    end
+
+    return x2
+
+    #return r
+  end
+
+  #this sets the new velocity of the ball once it has collided with this peg
+  def collide args
+    normalOfRCCollision = [                                                     #this is the normal of the collision in COMPONENT FORM
+      {x: @center.x, y: @center.y},                                             #see https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.mathscard.co.uk%2Fonline%2Fcircle-coordinate-geometry%2F&psig=AOvVaw2GcD-e2-nJR_IUKpw3hO98&ust=1605731315521000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCMjBo7e1iu0CFQAAAAAdAAAAABAD
+      {x: args.state.ball.center.x, y: args.state.ball.center.y},
+    ]
+
+    normalSlope = (                                                             #normalSlope is the slope of normalOfRCCollision
+      (normalOfRCCollision[1].y - normalOfRCCollision[0].y) /
+      (normalOfRCCollision[1].x - normalOfRCCollision[0].x)
+    )
+    slope = normalSlope**-1.0 * -1                                              # slope is the slope of the tangent
+    # args.state.display_value = slope
+    pointA = {                                                                  # pointA and pointB are using the var slope to tangent in COMPONENT FORM
+      x: args.state.ball.center.x-1,
+      y: -(slope-args.state.ball.center.y)
+    }
+    pointB = {
+      x: args.state.ball.center.x+1,
+      y: slope+args.state.ball.center.y
+    }
+
+    perpVect = {x: pointB.x - pointA.x, y:pointB.y - pointA.y}                  # perpVect is to be VECTOR of the perpendicular tangent
+    mag  = (perpVect.x**2 + perpVect.y**2)**0.5                                 # find the magniude of the perpVect
+    perpVect = {x: perpVect.x/(mag), y: perpVect.y/(mag)}                       # divide the perpVect by the magniude to make it a unit vector
+    perpVect = {x: -perpVect.y, y: perpVect.x}                                  # swap the x and y and multiply by -1 to make the vector perpendicular
+    args.state.display_value = perpVect
+    if perpVect.y > 0                                                           #ensure perpVect points upward
+      perpVect = {x: perpVect.x*-1, y: perpVect.y*-1}
+    end
+
+    previousPosition = {                                                        # calculate an ESTIMATE of the previousPosition of the ball
+      x:args.state.ball.center.x-args.state.ball.velocity.x,
+      y:args.state.ball.center.y-args.state.ball.velocity.y
+    }
+
+    yInterc = pointA.y + -slope*pointA.x
+    if slope == INFINITY                                                        # the perpVect presently either points in the correct dirrection or it is 180 degrees off we need to correct this
+      if previousPosition.x < pointA.x
+        perpVect = {x: perpVect.x*-1, y: perpVect.y*-1}
+        yInterc = -INFINITY
+      end
+    elsif previousPosition.y < slope*previousPosition.x + yInterc               # check if ball is bellow or above the collider to determine if perpVect is - or +
+      perpVect = {x: perpVect.x*-1, y: perpVect.y*-1}
+    end
+
+    velocityMag =                                                               # the current velocity magnitude of the ball
+      (args.state.ball.velocity.x**2 + args.state.ball.velocity.y**2)**0.5
+    theta_ball=
+      Math.atan2(args.state.ball.velocity.y,args.state.ball.velocity.x)         #the angle of the ball's velocity
+    theta_repel=
+      Math.atan2(args.state.ball.center.y,args.state.ball.center.x)             #the angle of the repelling force(perpVect)
+
+    fbx = velocityMag * Math.cos(theta_ball)                                    #the x component of the ball's velocity
+    fby = velocityMag * Math.sin(theta_ball)                                    #the y component of the ball's velocity
+    repelMag = getRepelMagnitude(                                               # the magniude of the collision vector
+      args,
+      fbx,
+      fby,
+      perpVect.x,
+      perpVect.y,
+      (args.state.ball.velocity.x**2 + args.state.ball.velocity.y**2)**0.5
+    )
+    frx = repelMag* Math.cos(theta_repel)                                       #the x component of the repel's velocity | magnitude is set to twice of fbx
+    fry = repelMag* Math.sin(theta_repel)                                       #the y component of the repel's velocity | magnitude is set to twice of fby
+
+    fsumx = fbx+frx                            # sum of x forces
+    fsumy = fby+fry                            # sum of y forces
+    fr = velocityMag                           # fr is the resulting magnitude
+    thetaNew = Math.atan2(fsumy, fsumx)        # thetaNew is the resulting angle
+    xnew = fr*Math.cos(thetaNew)               # resulting x velocity
+    ynew = fr*Math.sin(thetaNew)               # resulting y velocity
+    if (args.state.ball.center.x >= @center.x) # this is necessary for the ball colliding on the right side of the peg
+      xnew=xnew.abs
+    end
+
+    args.state.ball.velocity.x = xnew                                           # set the x-velocity to the new velocity
+    if args.state.ball.center.y > @center.y                                     # if the ball is above the middle of the peg we need to temporarily ignore some of the gravity
+      args.state.ball.velocity.y = ynew + GRAVITY * 0.01
+    else
+      args.state.ball.velocity.y = ynew - GRAVITY * 0.01                        # if the ball is bellow the middle of the peg we need to temporarily increase the power of the gravity
+    end
+
+    args.state.ball.center.x+= args.state.ball.velocity.x                       # update the position of the ball so it never looks like the ball is intersecting the circle
+    args.state.ball.center.y+= args.state.ball.velocity.y
+  end
+end
diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/app/vector2d.rb b/samples/04_physics_and_collisions/08_bouncing_on_collision/app/vector2d.rb
new file mode 100644
index 0000000..9cb1954
--- /dev/null
+++ b/samples/04_physics_and_collisions/08_bouncing_on_collision/app/vector2d.rb
@@ -0,0 +1,49 @@
+class Vector2d
+    attr_accessor :x, :y
+  
+    def initialize x=0, y=0
+      @x=x
+      @y=y
+    end
+  
+    #returns a vector multiplied by scalar x
+    #x [float] scalar
+    def mult x
+      r = Vector2d.new(0,0)
+      r.x=@x*x
+      r.y=@y*x
+      r
+    end
+  
+    # vect [Vector2d] vector to copy
+    def copy vect
+      Vector2d.new(@x, @y)
+    end
+  
+    #returns a new vector equivalent to this+vect
+    #vect [Vector2d] vector to add to self
+    def add vect
+      Vector2d.new(@x+vect.x,@y+vect.y)
+    end
+  
+    #returns a new vector equivalent to this-vect
+    #vect [Vector2d] vector to subtract to self
+    def sub vect
+      Vector2d.new(@x-vect.c, @y-vect.y)
+    end
+  
+    #return the magnitude of the vector
+    def mag
+      ((@x**2)+(@y**2))**0.5
+    end
+  
+    #returns a new normalize version of the vector
+    def normalize
+      Vector2d.new(@x/mag, @y/mag)
+    end
+  
+    #TODO delet?
+    def distABS vect
+      (((vect.x-@x)**2+(vect.y-@y)**2)**0.5).abs()
+    end
+  end
\ No newline at end of file
diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/LinearCollider.md b/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/LinearCollider.md
new file mode 100644
index 0000000..41227a2
--- /dev/null
+++ b/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/LinearCollider.md
@@ -0,0 +1,13 @@
+<br/>

+<img src="https://github.com/DragonRuby/dragonruby-game-toolkit-physics/blob/master/docs/docImages/LinearCollider_1.png?raw=true" width="300" height="271">

+<br/>

+<img src="https://github.com/DragonRuby/dragonruby-game-toolkit-physics/blob/master/docs/docImages/LinearCollider_2.png?raw=true" width="300" height="271">

+<br/>

+<img src="https://github.com/DragonRuby/dragonruby-game-toolkit-physics/blob/master/docs/docImages/LinearCollider_3.png?raw=true" width="300" height="271">

+<br/>

+<img src="https://github.com/DragonRuby/dragonruby-game-toolkit-physics/blob/master/docs/docImages/LinearCollider_4.png?raw=true" width="634" height="72">

+<br/>

+<img src="https://github.com/DragonRuby/dragonruby-game-toolkit-physics/blob/master/docs/docImages/LinearCollider_5.png?raw=true" width="1226" height="92">

+<br/>

+<img src="https://github.com/DragonRuby/dragonruby-game-toolkit-physics/blob/master/docs/docImages/LinearCollider_6.png?raw=true" width="300" height="271">

+<br/>

diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/docImages/LinearCollider_1.png b/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/docImages/LinearCollider_1.png
new file mode 100644
index 0000000..75c8271
--- /dev/null
+++ b/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/docImages/LinearCollider_1.png
diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/docImages/LinearCollider_2.png b/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/docImages/LinearCollider_2.png
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index 0000000..231a362
--- /dev/null
+++ b/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/docImages/LinearCollider_2.png
diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/docImages/LinearCollider_3.png b/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/docImages/LinearCollider_3.png
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index 0000000..5e552d3
--- /dev/null
+++ b/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/docImages/LinearCollider_3.png
diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/docImages/LinearCollider_4.png b/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/docImages/LinearCollider_4.png
new file mode 100644
index 0000000..c1284a3
--- /dev/null
+++ b/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/docImages/LinearCollider_4.png
diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/docImages/LinearCollider_5.png b/samples/04_physics_and_collisions/08_bouncing_on_collision/docs/docImages/LinearCollider_5.png
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--- /dev/null
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+++ b/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/ball.png
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diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/square-black.png b/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/square-black.png
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diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/square-blue.png b/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/square-blue.png
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diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/square-gray.png b/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/square-gray.png
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diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/square-green.png b/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/square-green.png
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diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/square-indigo.png b/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/square-indigo.png
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diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/square-orange.png b/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/square-orange.png
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diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/square-red.png b/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/square-red.png
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diff --git a/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/square-yellow.png b/samples/04_physics_and_collisions/08_bouncing_on_collision/sprites/square-yellow.png
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