Attention: Here be dragons

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# Curve2D¶

Inherits: Resource < RefCounted < 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` int point_count `0`

## Methods¶

 void add_point ( Vector2 position, Vector2 in=Vector2(0, 0), Vector2 out=Vector2(0, 0), int index=-1 ) void float get_baked_length ( ) const PackedVector2Array get_baked_points ( ) const float get_closest_offset ( Vector2 to_point ) const Vector2 get_closest_point ( Vector2 to_point ) const Vector2 get_point_in ( int idx ) const Vector2 get_point_out ( int idx ) const Vector2 get_point_position ( int idx ) const void remove_point ( int idx ) Vector2 sample ( int idx, float t ) const Vector2 sample_baked ( float offset=0.0, bool cubic=false ) const Transform2D sample_baked_with_rotation ( float offset=0.0, bool cubic=false ) const Vector2 samplef ( float fofs ) const void set_point_in ( int idx, Vector2 position ) void set_point_out ( int idx, Vector2 position ) void set_point_position ( int idx, Vector2 position ) PackedVector2Array tessellate ( int max_stages=5, float tolerance_degrees=4 ) const PackedVector2Array tessellate_even_length ( int max_stages=5, float tolerance_length=20.0 ) const

## Property Descriptions¶

float bake_interval = `5.0`

• void set_bake_interval ( float value )

• float 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.

int point_count = `0`

• void set_point_count ( int value )

• int get_point_count ( )

The number of points describing the curve.

## Method Descriptions¶

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

Adds a point with the specified `position` relative to the curve's own position, with control points `in` and `out`. Appends the new point at the end of the point list.

If `index` is given, the new point is inserted before the existing point identified by index `index`. Every existing point starting from `index` is shifted further down the list of points. The index must be greater than or equal to `0` and must not exceed the number of existing points in the line. See point_count.

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.

PackedVector2Array get_baked_points ( ) const

Returns the cache of points as a PackedVector2Array.

float get_closest_offset ( Vector2 to_point ) const

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

`to_point` must be in this curve's local space.

Vector2 get_closest_point ( Vector2 to_point ) const

Returns the closest point on baked segments (in curve's local space) to `to_point`.

`to_point` must be in this curve's local space.

Vector2 get_point_in ( int idx ) const

Returns the position of the control point leading to the vertex `idx`. The returned position is relative 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`. The returned position is relative 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_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)`.

void remove_point ( int idx )

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

Vector2 sample ( 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 sample_baked ( float offset=0.0, 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).

Transform2D sample_baked_with_rotation ( float offset=0.0, bool cubic=false ) const

Similar to sample_baked, but returns Transform2D that includes a rotation along the curve, with Transform2D.origin as the point position, Transform2D.x as the sideways vector, and Transform2D.y as the forward vector. Returns an empty transform if the length of the curve is `0`.

```var baked = curve.sample_baked_with_rotation(offset)
# This will rotate and position the node with the up direction pointing along the curve.
position = baked.get_origin()
rotation = baked.get_rotation()
# Alternatively, not preserving scale.
transform = baked * Transform2D.FLIP_Y
# To match the rotation of PathFollow2D, not preserving scale.
transform = Transform2D(baked.y, baked.x, baked.origin)
```

Vector2 samplef ( float fofs ) const

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

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. The position is relative to the vertex.

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. The position is relative to the vertex.

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.

PackedVector2Array 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 s