class Tickly::Curve
A shorthand class for Nuke's animation curves. Will convert a passed Curve
expression into a set of values, where all the values are baked per integer frames on the whole stretch of time where curve is defined
Constants
- KEYFRAME
- SECTION_START
Public Class Methods
new(curve_expression)
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The constructor accepts a Curve
expression as returned by the Parser
Normally it looks like this
[:c, "curve", "x1", "123", "456", ...]
# File lib/tickly/curve.rb, line 18 def initialize(curve_expression) raise InvalidCurveError, "A curve expression should have :c as it's first symbol" unless curve_expression[0] == :c raise InvalidCurveError, "Curve expression contained no values" unless curve_expression[2] # Nuke7 sometimes produces curves where the command is a string literal # within quotes, and it contains a trailing space cmd = curve_expression[1].to_s.strip raise InvalidCurveError, "Curve expression should start with a 'curve' command" unless cmd =~ /^curve/ # Compute the curve increment or decrement. It looks like a modifier: # "curve+5" means we have to add 5 to every value on the curve xformer = lambda { |v| v} # Identity if cmd =~ /^(curve)([+-])([\d\.]+)$/ operator = $2[0..1] # Ensure only one character gets through modifier = $3.to_f xformer = lambda{|v| v.send(operator, modifier) } end expand_curve(curve_expression, &xformer) end
Public Instance Methods
each(&blk)
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Returns each defined keyframe as a pair of a frame number and a value
# File lib/tickly/curve.rb, line 40 def each(&blk) @tuples.each(&blk) end
Private Instance Methods
expand_curve(curve_expression) { |$to_f| ... }
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# File lib/tickly/curve.rb, line 46 def expand_curve(curve_expression, &post_lambda) # Replace the closing curly brace with a curly brace with space so that it gets caught by split atoms = curve_expression[2..-1] # remove the :c curly designator and the "curve" keyword @tuples = [] # Nuke saves curves very efficiently. x(keyframe_number) means that an # uninterrupted sequence of values will start, after which values follow. # When the curve is interrupted in some way a new x(keyframe_number) will # signify that we skip to that specified keyframe and the curve continues # from there, in gap size defined by the last fragment. That is, # x1 1 x3 2 3 4 will place 2, 3 and 4 at 2-frame increments. # Thanks to Michael Lester for explaining this. last_processed_keyframe = 1 intraframe_gap_size = 1 while atom = atoms.shift if atom =~ SECTION_START last_processed_keyframe = $1.to_i if @tuples.any? last_captured_frame = @tuples[-1][0] intraframe_gap_size = last_processed_keyframe - last_captured_frame end elsif atom =~ KEYFRAME @tuples << [last_processed_keyframe, yield($1.to_f)] last_processed_keyframe += intraframe_gap_size end end end