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