Module: Zyps::Utility

Defined in:
lib/zyps.rb

Overview

Various methods for working with Vectors, etc.

Constant Summary collapse

PI2 =

:nodoc:

Math::PI * 2.0
@@caching_enabled =

Turn caching of return values on or off.

false

Class Method Summary collapse

Class Method Details

.caching_enabled=(value) ⇒ Object 



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# File 'lib/zyps.rb', line 552

def Utility.caching_enabled= (value)
	@@caching_enabled = value
	Utility.clear_caches if ! @@caching_enabled
end

.clear_caches ⇒ Object

Empty cached return values.



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# File 'lib/zyps.rb', line 542

def Utility.clear_caches
	@@angles = Hash.new {|h, k| h[k] = {}}
	@@distances = Hash.new {|h, k| h[k] = {}}
end

.collided?(object1, object2) ⇒ Boolean

Given two GameObjects, determine if the boundary of one crosses the boundary of the other.

Returns:

  • (Boolean) 


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# File 'lib/zyps.rb', line 639

def Utility.collided?(object1, object2)
	object1_radius = Math.sqrt(object1.size / Math::PI)
	object2_radius = Math.sqrt(object2.size / Math::PI)
	return true if find_distance(object1.location, object2.location) < object1_radius + object2_radius
	false
end

.constrain_value(value, absolute_maximum) ⇒ Object

Reduce a number to within an allowed maximum (or minimum, if the number is negative).



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# File 'lib/zyps.rb', line 619

def Utility.constrain_value(value, absolute_maximum)
	if (value.abs > absolute_maximum) then
		if value >= 0 then
			value = absolute_maximum
		else
			value = absolute_maximum * -1
		end
	end
	value
end

.find_angle(origin, target) ⇒ Object

Get the angle (in degrees) from one Location to another.



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# File 'lib/zyps.rb', line 558

def Utility.find_angle(origin, target)
	if @@caching_enabled
		#Return cached angle if there is one.
		return @@angles[origin][target] if @@angles[origin][target]
		return @@angles[target][origin] if @@angles[target][origin]
	end
	#Get vector from origin to target.
	x_difference = target.x - origin.x
	y_difference = target.y - origin.y
	#Get vector's angle.
	radians = Math.atan2(y_difference, x_difference)
	#Result will range from negative Pi to Pi, so correct it.
	radians += PI2 if radians < 0
	#Convert to degrees.
	angle = to_degrees(radians)
	#Cache angle if caching enabled.
	if @@caching_enabled
		@@angles[origin][target] = angle
		#angle + 180 = angle from target to origin.
		@@angles[target][origin] = (angle + 180 % 360)
	end
	#Return result.
	angle
end

.find_distance(origin, target) ⇒ Object

Get the distance from one Location to another.



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# File 'lib/zyps.rb', line 584

def Utility.find_distance(origin, target)
	if @@caching_enabled
		#Return cached distance if there is one.
		return @@distances[origin][target] if @@distances[origin][target]
	end
	#Get vector from origin to target.
	x_difference = origin.x - target.x
	y_difference = origin.y - target.y
	#Get distance.
	distance = Math.sqrt(x_difference ** 2 + y_difference ** 2)
	#Cache distance if caching enabled.
	if @@caching_enabled
		#Origin to target distance = target to origin distance.
		#Cache such that either will be found.
		@@distances[origin][target] = distance
		@@distances[target][origin] = distance
	end
	#Return result.
	distance
end

.find_reflection_angle(normal, angle) ⇒ Object

Given a normal and an angle, find the reflection angle.



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# File 'lib/zyps.rb', line 631

def Utility.find_reflection_angle(normal, angle)
	incidence_angle = normal - angle
	reflection_angle = normal + incidence_angle
	reflection_angle %= 360
	reflection_angle
end

.to_degrees(radians) ⇒ Object

Convert radians to degrees.



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# File 'lib/zyps.rb', line 606

def Utility.to_degrees(radians)
	radians / PI2 * 360
end

.to_radians(degrees) ⇒ Object

Convert degrees to radians.



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# File 'lib/zyps.rb', line 611

def Utility.to_radians(degrees)
	radians = degrees / 360.0 * PI2
	radians = radians % PI2
	radians += PI2 if radians < 0
	radians
end