Curve2D

Inherits: Resource < Reference < Object

Category: Core

Brief Description

Describes a Bezier curve in 2D space.

Member Functions

void add_point ( Vector2 pos, Vector2 in=Vector2(0,0), Vector2 out=Vector2(0,0), int atpos=-1 )
float get_bake_interval ( ) const
float get_baked_length ( ) const
Vector2Array 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_pos ( 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_bake_interval ( float distance )
void set_point_in ( int idx, Vector2 pos )
void set_point_out ( int idx, Vector2 pos )
void set_point_pos ( int idx, Vector2 pos )
Vector2Array tesselate ( 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

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

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

  • float get_bake_interval ( ) const

Returns the distance between two adjacent cached points.

  • 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.

Returns the cache of points as a Vector2Array.

  • int get_point_count ( ) const

Returns the number of points describing the curve.

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).

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).

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).

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).

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).

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_bake_interval ( float distance )

Sets the distance in pixels between two adjacent cached points. Changing it forces the cache to be recomputed the next time a xxx_baked_xxx function is called. The less distance, the more points the cache will have, and the more memory it will consume, so use with care.

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.

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.

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

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.