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"""Selection-buffer handling code |
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This code is resonsible for turning gluint * |
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arrays into structured representations for use |
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by Python-level code. |
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""" |
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from OpenGL._bytes import integer_types |
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def uintToLong( value ): |
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if value < 0: |
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value = (value & 0x7fffffff) + 0x80000000 |
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return value |
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class GLSelectRecord( object ): |
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"""Minimalist object for storing an OpenGL selection-buffer record |
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Provides near and far as *float* values by dividing by |
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self.DISTANCE_DIVISOR (2**32-1) |
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From the spec: |
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Depth values (which are in the range [0,1]) are multiplied by |
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2^32 - 1, before being placed in the hit record. |
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Names are unmodified, so normally are slices of the array passed in |
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to GLSelectRecord.fromArray( array ) |
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""" |
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DISTANCE_DIVISOR = float((2**32)-1) |
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__slots__ = ('near','far','names') |
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def fromArray( cls, array, total ): |
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"""Produce list with all records from the array""" |
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result = [] |
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index = 0 |
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arrayLength = len(array) |
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for item in range( total ): |
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if index + 2 >= arrayLength: |
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break |
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count = array[index] |
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near = array[index+1] |
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far = array[index+2] |
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names = [ uintToLong(v) for v in array[index+3:index+3+count]] |
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result.append( cls( near, far, names ) ) |
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index += 3+count |
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return result |
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fromArray = classmethod( fromArray ) |
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def __init__( self, near, far, names ): |
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"""Initialise/store the values""" |
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self.near = self.convertDistance( near ) |
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self.far = self.convertDistance( far ) |
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self.names = names |
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def convertDistance( self, value ): |
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"""Convert a distance value from array uint to 0.0-1.0 range float""" |
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return uintToLong( value ) / self.DISTANCE_DIVISOR |
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def __getitem__( self, key ): |
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"""Allow for treating the record as a three-tuple""" |
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if isinstance( key, integer_types): |
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return (self.near,self.far,self.names)[key] |
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elif key in self.__slots__: |
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try: |
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return getattr( self, key ) |
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except AttributeError as err: |
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raise KeyError( """Don't have an index/key %r for %s instant"""%( |
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key, self.__class__, |
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)) |
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