blender/release/scripts/freestyle/style_modules/long_anisotropically_dense.py

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#  Filename : long_anisotropically_dense.py
#  Author   : Stephane Grabli
#  Date     : 04/08/2005
#  Purpose  : Selects the lines that are long and have a high anisotropic 
#             a priori density and uses causal density 
#             to draw without cluttering. Ideally, half of the
#             selected lines are culled using the causal density.
#
#             ********************* WARNING *************************************
#             ******** The Directional a priori density maps must          ****** 
#             ******** have been computed prior to using this style module ******

from freestyle import ChainSilhouetteIterator, ConstantColorShader, ConstantThicknessShader, DensityF1D, \
    IntegrationType, Operators, QuantitativeInvisibilityUP1D, SamplingShader, UnaryPredicate1D
from PredicatesB1D import pyLengthBP1D
from PredicatesU1D import pyHighDensityAnisotropyUP1D, pyHigherLengthUP1D
from logical_operators import NotUP1D

## custom density predicate
class pyDensityUP1D(UnaryPredicate1D):
    def __init__(self, wsize, threshold, integration=IntegrationType.MEAN, sampling=2.0):
        UnaryPredicate1D.__init__(self)
        self._wsize = wsize
        self._threshold = threshold
        self._integration = integration
        self._func = DensityF1D(self._wsize, self._integration, sampling)
        self._func2 = DensityF1D(self._wsize, IntegrationType.MAX, sampling)
    def __call__(self, inter):
        c = self._func(inter)
        m = self._func2(inter)
        if c < self._threshold:
            return 1
        if m > 4*c:
            if c < 1.5*self._threshold:
                return 1
        return 0

Operators.select(QuantitativeInvisibilityUP1D(0))
Operators.bidirectional_chain(ChainSilhouetteIterator(),NotUP1D(QuantitativeInvisibilityUP1D(0)))
Operators.select(pyHigherLengthUP1D(40))
## selects lines having a high anisotropic a priori density
Operators.select(pyHighDensityAnisotropyUP1D(0.3,4))
Operators.sort(pyLengthBP1D())
shaders_list = [
    SamplingShader(2.0),
    ConstantThicknessShader(2),
    ConstantColorShader(0.2,0.2,0.25,1), 
    ]
## uniform culling
Operators.create(pyDensityUP1D(3.0,2.0e-2, IntegrationType.MEAN, 0.1), shaders_list)