Module: MiniGL::Movement

Included in:
GameObject
Defined in:
lib/minigl/movement.rb

Overview

This module provides objects with physical properties and methods for moving. It allows moving with or without collision checking (based on rectangular bounding boxes), including a method to behave as an elevator, affecting other objects’ positions as it moves.

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#bottom ⇒ Object (readonly)

The object that is making contact with this from below. If there’s no contact, returns nil.



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# File 'lib/minigl/movement.rb', line 189

def bottom
  @bottom
end

#h ⇒ Object (readonly)

Height of the bounding box.



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# File 'lib/minigl/movement.rb', line 177

def h
  @h
end

#left ⇒ Object (readonly)

The object that is making contact with this from the left. If there’s no contact, returns nil.



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# File 'lib/minigl/movement.rb', line 193

def left
  @left
end

#mass ⇒ Object (readonly)

The mass of the object, in arbitrary units. The default value for GameObject instances, for example, is 1. The larger the mass (i.e., the heavier the object), the more intense the forces applied to the object have to be in order to move it.



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# File 'lib/minigl/movement.rb', line 163

def mass
  @mass
end

#max_speed ⇒ Object (readonly)

A Vector with the speed limits for the object (x: horizontal component, y: vertical component).



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# File 'lib/minigl/movement.rb', line 171

def max_speed
  @max_speed
end

#passable ⇒ Object (readonly)

Whether a moving object can pass through this block when coming from below. This is a common feature of platforms in platform games.



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# File 'lib/minigl/movement.rb', line 181

def passable
  @passable
end

#prev_speed ⇒ Object (readonly)

:nodoc:



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# File 'lib/minigl/movement.rb', line 209

def prev_speed
  @prev_speed
end

#right ⇒ Object (readonly)

The object that is making contact with this from the right. If there’s no contact, returns nil.



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# File 'lib/minigl/movement.rb', line 197

def right
  @right
end

#speed ⇒ Object (readonly)

A Vector with the current speed of the object (x: horizontal component, y: vertical component).



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# File 'lib/minigl/movement.rb', line 167

def speed
  @speed
end

#stored_forces ⇒ Object

A Vector with the horizontal and vertical components of a force that be applied in the next time move is called.



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# File 'lib/minigl/movement.rb', line 207

def stored_forces
  @stored_forces
end

#top ⇒ Object (readonly)

The object that is making contact with this from above. If there’s no contact, returns nil.



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# File 'lib/minigl/movement.rb', line 185

def top
  @top
end

#w ⇒ Object (readonly)

Width of the bounding box.



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# File 'lib/minigl/movement.rb', line 174

def w
  @w
end

#x ⇒ Object

The x-coordinate of the top left corner of the bounding box.



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# File 'lib/minigl/movement.rb', line 200

def x
  @x
end

#y ⇒ Object

The y-coordinate of the top left corner of the bounding box.



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# File 'lib/minigl/movement.rb', line 203

def y
  @y
end

Instance Method Details

#bounds ⇒ Object

Returns the bounding box as a Rectangle.



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# File 'lib/minigl/movement.rb', line 212

def bounds
  Rectangle.new @x, @y, @w, @h
end

#cycle(points, speed, obstacles = nil) ⇒ Object

Causes the object to move in cycles across multiple given points (the first point in the array is the first point the object will move towards, so it doesn’t need to be equal to the current/initial position). If obstacles are provided, it will behave as an elevator (as in move_carrying).

Parameters:

points

An array of Vectors representing the path that the object will perform.

speed

The constant speed at which the object will move. This must be provided as a scalar, not a vector.

obstacles

An array of obstacles to be considered in the collision checking, and carried along when colliding from above. Obstacles must be instances of Block (or derived classes), or objects that include Movement.



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# File 'lib/minigl/movement.rb', line 438

def cycle(points, speed, obstacles = nil)
  @cur_point = 0 if @cur_point.nil?
  if obstacles
    move_carrying points[@cur_point], speed, obstacles
  else
    move_free points[@cur_point], speed
  end
  if @speed.x == 0 and @speed.y == 0
    if @cur_point == points.length - 1; @cur_point = 0
    else; @cur_point += 1; end
  end
end

#move(forces, obst, ramps) ⇒ Object

Moves this object, based on the forces being applied to it, and performing collision checking.

Parameters:

forces

A Vector where x is the horizontal component of the resulting force and y is the vertical component.

obst

An array of obstacles to be considered in the collision checking. Obstacles must be instances of Block (or derived classes), or objects that include Movement.

ramps

An array of ramps to be considered in the collision checking. Ramps must be instances of Ramp (or derived classes).



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# File 'lib/minigl/movement.rb', line 227

def move(forces, obst, ramps)
  forces.x += G.gravity.x; forces.y += G.gravity.y
  forces.x += @stored_forces.x; forces.y += @stored_forces.y
  @stored_forces.x = @stored_forces.y = 0

  forces.x = 0 if (forces.x < 0 and @left) or (forces.x > 0 and @right)
  forces.y = 0 if (forces.y < 0 and @top) or (forces.y > 0 and @bottom)

  if @bottom.is_a? Ramp and @bottom.ratio >= G.ramp_slip_threshold
    forces.x = (@bottom.left ? -1 : 1) * 0.1
  end

  @speed.x += forces.x / @mass; @speed.y += forces.y / @mass
  @speed.x = 0 if @speed.x.abs < G.min_speed.x
  @speed.y = 0 if @speed.y.abs < G.min_speed.y
  @speed.x = (@speed.x <=> 0) * @max_speed.x if @speed.x.abs > @max_speed.x
  @speed.y = (@speed.y <=> 0) * @max_speed.y if @speed.y.abs > @max_speed.y

  @prev_speed = @speed.clone

  x = @speed.x < 0 ? @x + @speed.x : @x
  y = @speed.y < 0 ? @y + @speed.y : @y
  w = @w + (@speed.x < 0 ? -@speed.x : @speed.x)
  h = @h + (@speed.y < 0 ? -@speed.y : @speed.y)
  move_bounds = Rectangle.new x, y, w, h
  coll_list = []
  obst.each do |o|
    coll_list << o if move_bounds.intersect? o.bounds
  end
  ramps.each do |r|
    r.check_can_collide move_bounds
  end

  if coll_list.length > 0
    up = @speed.y < 0; rt = @speed.x > 0; dn = @speed.y > 0; lf = @speed.x < 0
    if @speed.x == 0 || @speed.y == 0
      # Ortogonal
      if rt; x_lim = find_right_limit coll_list
      elsif lf; x_lim = find_left_limit coll_list
      elsif dn; y_lim = find_down_limit coll_list
      elsif up; y_lim = find_up_limit coll_list
      end
      if rt && @x + @w + @speed.x > x_lim
        @x = x_lim - @w
        @speed.x = 0
      elsif lf && @x + @speed.x < x_lim
        @x = x_lim
        @speed.x = 0
      elsif dn && @y + @h + @speed.y > y_lim; @y = y_lim - @h; @speed.y = 0
      elsif up && @y + @speed.y < y_lim; @y = y_lim; @speed.y = 0
      end
    else
      # Diagonal
      x_aim = @x + @speed.x + (rt ? @w : 0); x_lim_def = x_aim
      y_aim = @y + @speed.y + (dn ? @h : 0); y_lim_def = y_aim
      coll_list.each do |c|
        if c.passable; x_lim = x_aim
        elsif rt; x_lim = c.x
        else; x_lim = c.x + c.w
        end
        if dn; y_lim = c.y
        elsif c.passable; y_lim = y_aim
        else; y_lim = c.y + c.h
        end

        if c.passable
          y_lim_def = y_lim if dn && @y + @h <= y_lim && y_lim < y_lim_def
        elsif (rt && @x + @w > x_lim) || (lf && @x < x_lim)
          # Can't limit by x, will limit by y
          y_lim_def = y_lim if (dn && y_lim < y_lim_def) || (up && y_lim > y_lim_def)
        elsif (dn && @y + @h > y_lim) || (up && @y < y_lim)
          # Can't limit by y, will limit by x
          x_lim_def = x_lim if (rt && x_lim < x_lim_def) || (lf && x_lim > x_lim_def)
        else
          x_time = 1.0 * (x_lim - @x - (@speed.x < 0 ? 0 : @w)) / @speed.x
          y_time = 1.0 * (y_lim - @y - (@speed.y < 0 ? 0 : @h)) / @speed.y
          if x_time > y_time
            # Will limit by x
            x_lim_def = x_lim if (rt && x_lim < x_lim_def) || (lf && x_lim > x_lim_def)
          elsif (dn && y_lim < y_lim_def) || (up && y_lim > y_lim_def)
            y_lim_def = y_lim
          end
        end
      end
      if x_lim_def != x_aim
        @speed.x = 0
        if lf; @x = x_lim_def
        else; @x = x_lim_def - @w
        end
      end
      if y_lim_def != y_aim
        @speed.y = 0
        if up; @y = y_lim_def
        else; @y = y_lim_def - @h
        end
      end
    end
  end
  @x += @speed.x
  @y += @speed.y

  # Keeping contact with ramp
  # if @speed.y == 0 and @speed.x.abs <= G.ramp_contact_threshold and @bottom.is_a? Ramp
  #   @y = @bottom.get_y(self)
  #   puts 'aqui'
  # end
  ramps.each do |r|
    r.check_intersection self
  end
  check_contact obst, ramps
end

#move_carrying(aim, speed, obstacles) ⇒ Object

Moves this object as an elevator (i.e., potentially carrying other objects) towards a given point.

Parameters:

aim

A Vector specifying where the object will move to.

speed

The constant speed at which the object will move. This must be provided as a scalar, not a vector.

obstacles

An array of obstacles to be considered in the collision checking, and carried along when colliding from above. Obstacles must be instances of Block (or derived classes), or objects that include Movement.



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# File 'lib/minigl/movement.rb', line 350

def move_carrying(aim, speed, obstacles)
  x_d = aim.x - @x; y_d = aim.y - @y
  distance = Math.sqrt(x_d**2 + y_d**2)

  if distance == 0
    @speed.x = @speed.y = 0
    return
  end

  @speed.x = 1.0 * x_d * speed / distance
  @speed.y = 1.0 * y_d * speed / distance

  x_aim = @x + @speed.x; y_aim = @y + @speed.y
  passengers = []
  obstacles.each do |o|
    if @x + @w > o.x && o.x + o.w > @x
      foot = o.y + o.h
      if foot.round(6) == @y.round(6) || @speed.y < 0 && foot < @y && foot > y_aim
        passengers << o
      end
    end
  end

  if @speed.x > 0 && x_aim >= aim.x || @speed.x < 0 && x_aim <= aim.x
    passengers.each do |p| p.x += aim.x - @x end
    @x = aim.x; @speed.x = 0
  else
    passengers.each do |p| p.x += @speed.x end
    @x = x_aim
  end
  if @speed.y > 0 && y_aim >= aim.y || @speed.y < 0 && y_aim <= aim.y
    @y = aim.y; @speed.y = 0
  else
    @y = y_aim
  end

  passengers.each do |p| p.y = @y - p.h end
end

#move_free(aim, speed) ⇒ Object

Moves this object, without performing any collision checking, towards the specified point.

Parameters:

aim

A Vector specifying where the object will move to.

speed

The constant speed at which the object will move. This must be provided as a scalar, not a vector.



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# File 'lib/minigl/movement.rb', line 396

def move_free(aim, speed)
  x_d = aim.x - @x; y_d = aim.y - @y
  distance = Math.sqrt(x_d**2 + y_d**2)

  if distance == 0
    @speed.x = @speed.y = 0
    return
  end

  @speed.x = 1.0 * x_d * speed / distance
  @speed.y = 1.0 * y_d * speed / distance

  if (@speed.x < 0 and @x + @speed.x <= aim.x) or (@speed.x >= 0 and @x + @speed.x >= aim.x)
    @x = aim.x
    @speed.x = 0
  else
    @x += @speed.x
  end

  if (@speed.y < 0 and @y + @speed.y <= aim.y) or (@speed.y >= 0 and @y + @speed.y >= aim.y)
    @y = aim.y
    @speed.y = 0
  else
    @y += @speed.y
  end
end