/Godot 3.0

Curve2D

Inherits: Resource < Reference < Object

Category: Core

Brief Description

Describes a Bezier curve in 2D space.

Member Functions

 void add_point ( Vector2 position, Vector2 in=Vector2( 0, 0 ), Vector2 out=Vector2( 0, 0 ), int at_position=-1 ) void clear_points ( ) float get_baked_length ( ) const PoolVector2Array get_baked_points ( ) const int get_point_count ( ) const Vector2 get_point_in ( int idx ) const Vector2 get_point_out ( int idx ) const Vector2 get_point_position ( int idx ) const Vector2 interpolate ( int idx, float t ) const Vector2 interpolate_baked ( float offset, bool cubic=false ) const Vector2 interpolatef ( float fofs ) const void remove_point ( int idx ) void set_point_in ( int idx, Vector2 position ) void set_point_out ( int idx, Vector2 position ) void set_point_position ( int idx, Vector2 position ) PoolVector2Array tessellate ( int max_stages=5, float tolerance_degrees=4 ) const

Description

This class describes a Bezier curve in 2D space. It is mainly used to give a shape to a Path2D, but can be manually sampled for other purposes.

It keeps a cache of precalculated points along the curve, to speed further calculations up.

Member Function Description

void add_point ( Vector2 position, Vector2 in=Vector2( 0, 0 ), Vector2 out=Vector2( 0, 0 ), int at_position=-1 )

Adds a point to a curve, at “position”, with control points “in” and “out”.

If “at_position” is given, the point is inserted before the point number “at_position”, moving that point (and every point after) after the inserted point. If “at_position” is not given, or is an illegal value (at_position <0 or at_position >= get_point_count), the point will be appended at the end of the point list.

void clear_points ( )

Removes all points from the curve.

float get_baked_length ( ) const

Returns the total length of the curve, based on the cached points. Given enough density (see set_bake_interval), it should be approximate enough.

PoolVector2Array get_baked_points ( ) const

Returns the cache of points as a PoolVector2Array.

int get_point_count ( ) const

Returns the number of points describing the curve.

Vector2 get_point_in ( int idx ) const

Returns the position of the control point leading to the vertex “idx”. If the index is out of bounds, the function sends an error to the console, and returns (0, 0).

Vector2 get_point_out ( int idx ) const

Returns the position of the control point leading out of the vertex “idx”. If the index is out of bounds, the function sends an error to the console, and returns (0, 0).

Vector2 get_point_position ( int idx ) const

Returns the position of the vertex “idx”. If the index is out of bounds, the function sends an error to the console, and returns (0, 0).

Vector2 interpolate ( int idx, float t ) const

Returns the position between the vertex “idx” and the vertex “idx”+1, where “t” controls if the point is the first vertex (t = 0.0), the last vertex (t = 1.0), or in between. Values of “t” outside the range (0.0 >= t <=1) give strange, but predictable results.

If “idx” is out of bounds it is truncated to the first or last vertex, and “t” is ignored. If the curve has no points, the function sends an error to the console, and returns (0, 0).

Vector2 interpolate_baked ( float offset, bool cubic=false ) const

Returns a point within the curve at position “offset”, where “offset” is measured as a pixel distance along the curve.

To do that, it finds the two cached points where the “offset” lies between, then interpolates the values. This interpolation is cubic if “cubic” is set to true, or linear if set to false.

Cubic interpolation tends to follow the curves better, but linear is faster (and often, precise enough).

Vector2 interpolatef ( float fofs ) const

Returns the position at the vertex “fofs”. It calls interpolate using the integer part of fofs as “idx”, and its fractional part as “t”.

void remove_point ( int idx )

Deletes the point “idx” from the curve. Sends an error to the console if “idx” is out of bounds.

void set_point_in ( int idx, Vector2 position )

Sets the position of the control point leading to the vertex “idx”. If the index is out of bounds, the function sends an error to the console.

void set_point_out ( int idx, Vector2 position )

Sets the position of the control point leading out of the vertex “idx”. If the index is out of bounds, the function sends an error to the console.

void set_point_position ( int idx, Vector2 position )

Sets the position for the vertex “idx”. If the index is out of bounds, the function sends an error to the console.

PoolVector2Array tessellate ( int max_stages=5, float tolerance_degrees=4 ) const

Returns a list of points along the curve, with a curvature controlled point density. That is, the curvier parts will have more points than the straighter parts.

This approximation makes straight segments between each point, then subdivides those segments until the resulting shape is similar enough.

“max_stages” controls how many subdivisions a curve segment may face before it is considered approximate enough. Each subdivision splits the segment in half, so the default 5 stages may mean up to 32 subdivisions per curve segment. Increase with care!

“tolerance_degrees” controls how many degrees the midpoint of a segment may deviate from the real curve, before the segment has to be subdivided.

© 2014–2018 Juan Linietsky, Ariel Manzur, Godot Engine contributors