Class: Metro::UI::PhysicsSprite

Inherits:
Sprite show all
Defined in:
lib/metro/models/ui/physics_sprite.rb

Overview

A physics sprite is a Metro model that is specially designed to draw and manage an image. A sprite maintains an image, location information, and rotation. It also has a physics body and shape to assist with being placed within a ‘Metro::UI::Space`.

Constant Summary

Constants included from Metro::Units

Metro::Units::Bounds

Instance Attribute Summary collapse

Attributes inherited from Sprite

#angle, #center_x, #center_y, #color, #dimensions, #image, #position, #scale

Attributes inherited from Model

#scene, #window

Instance Method Summary collapse

Methods inherited from Sprite

#bottom, #bounds, #left, #right, #top

Methods inherited from Model

#_load, #_save, #after_initialize, #bounds, #create, #draw_completed?, hierarchy, inherited, #initialize, metro_name, #model, model_name, models, #name, #notification, #saveable_to_view, #to_hash, #update_completed?

Methods included from HasEvents

included

Methods included from KeyValueCoding

#get, #set

Methods included from PropertyOwner

included, #properties

Constructor Details

This class inherits a constructor from Metro::Model

Instance Attribute Details

#debug ⇒ Object

When this value is true the bounding box will be placed around the sprite. This is useful in determining correct sizes and collisions.



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# File 'lib/metro/models/ui/physics_sprite.rb', line 36

property :debug, type: :boolean, default: false

#mass ⇒ Object

The mass specified here is given to the body.



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# File 'lib/metro/models/ui/physics_sprite.rb', line 14

property :mass, default: 10

#moment_of_interia ⇒ Object

The moment of inertia determines how the sprite will react to the forces applied to it.



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# File 'lib/metro/models/ui/physics_sprite.rb', line 19

property :moment_of_interia, default: 1000000

#shape_name ⇒ Object

The name of the shape. This name is important when the space defines actions based on the collision of particular objects. By default all physics sprites are named ‘object’.



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# File 'lib/metro/models/ui/physics_sprite.rb', line 31

property :shape_name, type: :text, default: "object"

#shape_size ⇒ Object

A physics sprite has by default a collision shape that is a square. So this property defines the length of one side which is used to create the appropriately sized shape for the sprite.



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# File 'lib/metro/models/ui/physics_sprite.rb', line 25

property :shape_size, default: 48.0

Instance Method Details

#body ⇒ Object

Returns the body of the physics sprite that is created with the mass and moment of interia specified in the other properties.

Returns:

  • the body of the physics sprite that is created with the mass and moment of interia specified in the other properties.



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# File 'lib/metro/models/ui/physics_sprite.rb', line 40

def body
  @body ||= begin
    body = CP::Body.new(mass,moment_of_interia)
    body.p = CP::Vec2::ZERO
    body.v = CP::Vec2::ZERO
    body.a = 0
    body
  end
end

#draw ⇒ Object

On draw, draw the specified sprite.



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# File 'lib/metro/models/ui/physics_sprite.rb', line 90

def draw
  angle_in_degrees = body.a.radians.to_degrees
  image.draw_rot(x,y,z_order,angle_in_degrees)

  draw_bounding_box if debug
end

#draw_bounding_box ⇒ Object 



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# File 'lib/metro/models/ui/physics_sprite.rb', line 97

def draw_bounding_box
  @bounding_box_border ||= create "metro::ui::border"
  @bounding_box_border.position = Point.at(position.x - shape_size,shape.bb.t)
  @bounding_box_border.dimensions = Dimensions.of(shape.bb.r - shape.bb.l,shape.bb.b - shape.bb.t)
  @bounding_box_border.draw
end

#push(x_amount, y_amount) ⇒ Object

An helper method that makes it easy to apply an impulse to the body at the center of the body. The impulse provided is in two parameters, the x and y component.



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# File 'lib/metro/models/ui/physics_sprite.rb', line 72

def push(x_amount,y_amount)
  body.apply_impulse(CP::Vec2.new(x_amount,y_amount),CP::Vec2.new(0.0, 0.0))
end

#shape ⇒ Object

Returns a polygon shape for the physics sprite with the size based on the ‘shape_size` property value.

Returns:

  • a polygon shape for the physics sprite with the size based on the ‘shape_size` property value.



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# File 'lib/metro/models/ui/physics_sprite.rb', line 52

def shape
  @shape ||= begin
    poly_array = [ [ -1 * shape_size, -1 * shape_size ],
      [ -1 * shape_size, shape_size ],
      [ shape_size, shape_size ],
      [ shape_size, -1 * shape_size ] ].map do |x,y|
        CP::Vec2.new(x,y)
    end

    new_shape = CP::Shape::Poly.new(body,poly_array, CP::Vec2::ZERO)
    new_shape.collision_type = shape_name.to_sym
    new_shape.e = 0.0
    new_shape

  end
end

#show ⇒ Object

Upon the scene start the body is assigned the x and y position. If this method is overriden the position will need to be set manually.



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# File 'lib/metro/models/ui/physics_sprite.rb', line 78

def show
  body.p = CP::Vec2.new(x,y)
end

#update ⇒ Object

On update track the position of the sprite based on the position of the physics body.



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# File 'lib/metro/models/ui/physics_sprite.rb', line 84

def update
  self.x = body.p.x
  self.y = body.p.y
end