The L-SIF Semantics


 

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L-SIF Lexical Conventions

L-SIF is an ASCII file format which is similar lexically to C code. It does not have a preprocessor, or any macro text facilities.

L-SIF Semantics

( LSIF major_version minor_version header_list layer_list )
TYPE:
FILE
PARAMETERS:
INT major_version, minor_version
HEADER header_list
LAYER layer_list
DESCRIPTION:
This is a L-SIF file of the corresponding version number. The header_list has some global, default parameter declarations, and the layer_list is the description of layers.
( units mm / inches )
TYPE:
HEADER
PARAMETERS:
UNIT_SPECIFICATION mm / inches
DESCRIPTION:
The units header field tells what units the file is in. Currently, the choices are millimeters or inches, because those units make the most sense given the build volumes and accuracies of current SFF machines
( desired_accuracy error )
TYPE:
HEADER
PARAMETERS:
VALUE error
DESCRIPTION:
The desired_accuracy header field is a global error tolerance for manufacturing. It implies that the designer will accept a part whose measurements end up being + or - error from the ideal geometry described when it is actually manufactured.
( thickness thick )
TYPE:
HEADER
PARAMETERS:
VALUE thick
DESCRIPTION:
The thickness header field tells the thickness of all the layers of a part, or the  thickness of a single layer with the unit specified in the units header .
( layer header vertex_list 1d_set_list )
TYPE:
LAYER
PARAMETERS:
HEADER header
VERTEX vertex_list
1D_SET 1d_set_list
DESCRIPTION:
A layer is a 2D geometry shape describing a slice of a SFF part. It is made up of planar polygons defined by vertices. The vertices of each polygon must be in counter-clockwise or clockwise order.
( contour contour_property_list vertex_list contour_segment_list )
TYPE:
CONTOUR
PARAMETERS:
CONTOUR_PROPERTY contour_property_list
VERTEX vertex_list
SEGMENT contour_segment_list
DESCRIPTION:
A contour is a closed 2D geometry shape defined by vertices in counter-clockwise or clockwise order.
( nested1d nested_1d_property_list vertex_list contour nested_1d_list )
TYPE:
NESTED_1D
PARAMETERS:
NESTED_1D_PROPERTY nested1d_1d_list
VERTEX vertex_list
CONTOUR contour
NESTED1D nested1d_1d_list
DESCRIPTION:
 A nested1d is a set of contours which are strictly nested inside a single outer contour.
( union 1d_set_list )
TYPE:
1D_SET
PARAMETERS:
1D_SET 1d_set_list
DESCRIPTION:
A boolean union operator. The result is the union of the arguments (whether single
1d_sets or boolean trees). 
( intersection 1d_set_list )
TYPE:
1D_SET
PARAMETERS:
1D_SET 1d_set_list
DESCRIPTION:
A boolean intersection operator. All of the arguments (whether single 1d_sets or boolean trees) are intersected to obtain the result.
( difference 1d_set_list )
TYPE:
1D_SET
PARAMETERS:
1D_SET 1d_set_list
DESCRIPTION:
A boolean difference operator. The first argument (whether a single 1d_set or a boolean tree) is the positive volume from which the geometry of subsequent arguments is subtracted.
( color color_setting ) 
TYPE:
CONTOUR_PROPERTY | NESTED_1D_PROPERTY
PARAMETERS:
COLOR_SETTING color_setting 
DESCRIPTION:
The color specification may be used either as a nested_1d property for the whole nested_1d or as a contour property on individual contours. A color contour property over-rides a color nested_1d property containing that contour. 
( rgb r g b ) 
TYPE:
COLOR_SETTING
PARAMETERS:
VALUE r 
VALUE g
VALUE b
DESCRIPTION:
An specification of color as an RGB coordinate triple. The arguments should all be values between 0.0 and 1.0. 
( v id x y )
TYPE:
VERTEX
PARAMETERS:
INT id
VALUE x
VALUE y
DESCRIPTION:
This is a vertex named id and located at (x, y ) 
( e value exponent )
TYPE:
EXP
PARAMETERS:
INT value
INT exponent
DESCRIPTION:
Floating point precision independent numerical format. The meaning of which = value * (10 ^ exponent).
int
TYPE:
INT
PARAMETERS:
INT int
DESCRIPTION:
The integer value int
decimal
TYPE:
DECIMAL
PARAMETERS:
DECIMAL decimal
DESCRIPTION:
The decimal value decimal


 

This page is maintained by Jianlin Wang
E-mail: jianlin@cs.berkeley.edu
Last modified: 12/21/99

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