Curve2D

Inherits: Resource < Reference < Object

Describes a Bézier curve in 2D space.

Description

This class describes a Bézier 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 up further calculations.

Properties

float

bake_interval

5.0

Methods

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
float	get_closest_offset ( Vector2 to_point ) const
Vector2	get_closest_point ( Vector2 to_point ) 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

Property Descriptions

float bake_interval

Default	5.0
Setter	set_bake_interval(value)
Getter	get_bake_interval()

The distance in pixels between two adjacent cached points. Changing it forces the cache to be recomputed the next time the get_baked_points or get_baked_length function is called. The smaller the distance, the more points in the cache and the more memory it will consume, so use with care.

Method Descriptions

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 >= [method 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 bake_interval), it should be approximate enough.

PoolVector2Array get_baked_points ( ) const

Returns the cache of points as a PoolVector2Array.

float get_closest_offset ( Vector2 to_point ) const

Returns the closest offset to to_point. This offset is meant to be used in interpolate_baked.

to_point must be in this curve's local space.

Vector2 get_closest_point ( Vector2 to_point ) const

Returns the closest point (in curve's local space) to to_point.

to_point must be in this curve's local space.

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.