9.11. Geometric Functions and Operators (original) (raw)

geometrictype + point → _`geometrictype`_

Adds the coordinates of the second point to those of each point of the first argument, thus performing translation. Available for point, box, path, circle.

box '(1,1),(0,0)' + point '(2,0)' → (3,1),(2,0)

path + path → path

Concatenates two open paths (returns NULL if either path is closed).

path '[(0,0),(1,1)]' + path '[(2,2),(3,3),(4,4)]' → [(0,0),(1,1),(2,2),(3,3),(4,4)]

geometrictype - point → _`geometrictype`_

Subtracts the coordinates of the second point from those of each point of the first argument, thus performing translation. Available for point, box, path, circle.

box '(1,1),(0,0)' - point '(2,0)' → (-1,1),(-2,0)

geometrictype * point → _`geometrictype`_

Multiplies each point of the first argument by the second point (treating a point as being a complex number represented by real and imaginary parts, and performing standard complex multiplication). If one interprets the second point as a vector, this is equivalent to scaling the object's size and distance from the origin by the length of the vector, and rotating it counterclockwise around the origin by the vector's angle from the x axis. Available for point, box,[a] path, circle.

path '((0,0),(1,0),(1,1))' * point '(3.0,0)' → ((0,0),(3,0),(3,3))

path '((0,0),(1,0),(1,1))' * point(cosd(45), sind(45)) → ((0,0),​(0.7071067811865475,0.7071067811865475),​(0,1.414213562373095))

geometrictype / point → _`geometrictype`_

Divides each point of the first argument by the second point (treating a point as being a complex number represented by real and imaginary parts, and performing standard complex division). If one interprets the second point as a vector, this is equivalent to scaling the object's size and distance from the origin down by the length of the vector, and rotating it clockwise around the origin by the vector's angle from the x axis. Available for point, box,[a] path, circle.

path '((0,0),(1,0),(1,1))' / point '(2.0,0)' → ((0,0),(0.5,0),(0.5,0.5))

path '((0,0),(1,0),(1,1))' / point(cosd(45), sind(45)) → ((0,0),​(0.7071067811865476,-0.7071067811865476),​(1.4142135623730951,0))

@-@ geometrictype → double precision

Computes the total length. Available for lseg, path.

@-@ path '[(0,0),(1,0),(1,1)]' → 2

@@ geometrictype → point

Computes the center point. Available for box, lseg, polygon, circle.

@@ box '(2,2),(0,0)' → (1,1)

# geometrictype → integer

Returns the number of points. Available for path, polygon.

# path '((1,0),(0,1),(-1,0))' → 3

geometrictype # geometrictype → point

Computes the point of intersection, or NULL if there is none. Available for lseg, line.

lseg '[(0,0),(1,1)]' # lseg '[(1,0),(0,1)]' → (0.5,0.5)

box # box → box

Computes the intersection of two boxes, or NULL if there is none.

box '(2,2),(-1,-1)' # box '(1,1),(-2,-2)' → (1,1),(-1,-1)

geometrictype ## geometrictype → point

Computes the closest point to the first object on the second object. Available for these pairs of types: (point, box), (point, lseg), (point, line), (lseg, box), (lseg, lseg), (line, lseg).

point '(0,0)' ## lseg '[(2,0),(0,2)]' → (1,1)

geometrictype <-> geometrictype → double precision

Computes the distance between the objects. Available for all seven geometric types, for all combinations of point with another geometric type, and for these additional pairs of types: (box, lseg), (lseg, line), (polygon, circle) (and the commutator cases).

circle '<(0,0),1>' <-> circle '<(5,0),1>' → 3

geometrictype @> geometrictype → boolean

Does first object contain second? Available for these pairs of types: (box, point), (box, box), (path, point), (polygon, point), (polygon, polygon), (circle, point), (circle, circle).

circle '<(0,0),2>' @> point '(1,1)' → t

geometrictype <@ geometrictype → boolean

Is first object contained in or on second? Available for these pairs of types: (point, box), (point, lseg), (point, line), (point, path), (point, polygon), (point, circle), (box, box), (lseg, box), (lseg, line), (polygon, polygon), (circle, circle).

point '(1,1)' <@ circle '<(0,0),2>' → t

geometrictype && geometrictype → boolean

Do these objects overlap? (One point in common makes this true.) Available for box, polygon, circle.

box '(1,1),(0,0)' && box '(2,2),(0,0)' → t

geometrictype << geometrictype → boolean

Is first object strictly left of second? Available for point, box, polygon, circle.

circle '<(0,0),1>' << circle '<(5,0),1>' → t

geometrictype >> geometrictype → boolean

Is first object strictly right of second? Available for point, box, polygon, circle.

circle '<(5,0),1>' >> circle '<(0,0),1>' → t

geometrictype &< geometrictype → boolean

Does first object not extend to the right of second? Available for box, polygon, circle.

box '(1,1),(0,0)' &< box '(2,2),(0,0)' → t

geometrictype &> geometrictype → boolean

Does first object not extend to the left of second? Available for box, polygon, circle.

box '(3,3),(0,0)' &> box '(2,2),(0,0)' → t

geometrictype <<| geometrictype → boolean

Is first object strictly below second? Available for point, box, polygon, circle.

box '(3,3),(0,0)' <<| box '(5,5),(3,4)' → t

geometrictype |>> geometrictype → boolean

Is first object strictly above second? Available for point, box, polygon, circle.

box '(5,5),(3,4)' |>> box '(3,3),(0,0)' → t

geometrictype &<| geometrictype → boolean

Does first object not extend above second? Available for box, polygon, circle.

box '(1,1),(0,0)' &<| box '(2,2),(0,0)' → t

geometrictype |&> geometrictype → boolean

Does first object not extend below second? Available for box, polygon, circle.

box '(3,3),(0,0)' |&> box '(2,2),(0,0)' → t

box <^ box → boolean

Is first object below second (allows edges to touch)?

box '((1,1),(0,0))' <^ box '((2,2),(1,1))' → t

box >^ box → boolean

Is first object above second (allows edges to touch)?

box '((2,2),(1,1))' >^ box '((1,1),(0,0))' → t

geometrictype ?# geometrictype → boolean

Do these objects intersect? Available for these pairs of types: (box, box), (lseg, box), (lseg, lseg), (lseg, line), (line, box), (line, line), (path, path).

lseg '[(-1,0),(1,0)]' ?# box '(2,2),(-2,-2)' → t

?- line → boolean

?- lseg → boolean

Is line horizontal?

?- lseg '[(-1,0),(1,0)]' → t

point ?- point → boolean

Are points horizontally aligned (that is, have same y coordinate)?

point '(1,0)' ?- point '(0,0)' → t

?| line → boolean

?| lseg → boolean

Is line vertical?

?| lseg '[(-1,0),(1,0)]' → f

point ?| point → boolean

Are points vertically aligned (that is, have same x coordinate)?

point '(0,1)' ?| point '(0,0)' → t

line ?-| line → boolean

lseg ?-| lseg → boolean

Are lines perpendicular?

lseg '[(0,0),(0,1)]' ?-| lseg '[(0,0),(1,0)]' → t

line ?|| line → boolean

lseg ?|| lseg → boolean

Are lines parallel?

lseg '[(-1,0),(1,0)]' ?|| lseg '[(-1,2),(1,2)]' → t

geometrictype ~= geometrictype → boolean

Are these objects the same? Available for point, box, polygon, circle.

polygon '((0,0),(1,1))' ~= polygon '((1,1),(0,0))' → t