91e9ad92f5
The main change is to caculate tangent directly from bezier curve, without going through discretized polyline, avoiding pitfalls of discretization. A similar refacor had been applied to Curve3D. The test cases for Curve2D is updated, comparing floating point with is_equal_approxmiate() instead of `==`, in order to avoid float precision problem.
177 lines
9.6 KiB
XML
177 lines
9.6 KiB
XML
<?xml version="1.0" encoding="UTF-8" ?>
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<class name="Curve2D" inherits="Resource" version="4.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../class.xsd">
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<brief_description>
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Describes a Bézier curve in 2D space.
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</brief_description>
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<description>
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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.
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It keeps a cache of precalculated points along the curve, to speed up further calculations.
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</description>
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<tutorials>
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</tutorials>
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<methods>
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<method name="add_point">
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<return type="void" />
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<param index="0" name="position" type="Vector2" />
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<param index="1" name="in" type="Vector2" default="Vector2(0, 0)" />
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<param index="2" name="out" type="Vector2" default="Vector2(0, 0)" />
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<param index="3" name="index" type="int" default="-1" />
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<description>
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Adds a point with the specified [param position] relative to the curve's own position, with control points [param in] and [param out]. Appends the new point at the end of the point list.
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If [param index] is given, the new point is inserted before the existing point identified by index [param index]. Every existing point starting from [param index] is shifted further down the list of points. The index must be greater than or equal to [code]0[/code] and must not exceed the number of existing points in the line. See [member point_count].
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</description>
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</method>
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<method name="clear_points">
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<return type="void" />
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<description>
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Removes all points from the curve.
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</description>
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</method>
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<method name="get_baked_length" qualifiers="const">
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<return type="float" />
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<description>
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Returns the total length of the curve, based on the cached points. Given enough density (see [member bake_interval]), it should be approximate enough.
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</description>
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</method>
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<method name="get_baked_points" qualifiers="const">
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<return type="PackedVector2Array" />
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<description>
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Returns the cache of points as a [PackedVector2Array].
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</description>
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</method>
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<method name="get_closest_offset" qualifiers="const">
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<return type="float" />
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<param index="0" name="to_point" type="Vector2" />
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<description>
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Returns the closest offset to [param to_point]. This offset is meant to be used in [method sample_baked].
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[param to_point] must be in this curve's local space.
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</description>
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</method>
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<method name="get_closest_point" qualifiers="const">
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<return type="Vector2" />
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<param index="0" name="to_point" type="Vector2" />
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<description>
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Returns the closest point on baked segments (in curve's local space) to [param to_point].
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[param to_point] must be in this curve's local space.
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</description>
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</method>
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<method name="get_point_in" qualifiers="const">
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<return type="Vector2" />
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<param index="0" name="idx" type="int" />
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<description>
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Returns the position of the control point leading to the vertex [param idx]. The returned position is relative to the vertex [param idx]. If the index is out of bounds, the function sends an error to the console, and returns [code](0, 0)[/code].
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</description>
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</method>
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<method name="get_point_out" qualifiers="const">
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<return type="Vector2" />
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<param index="0" name="idx" type="int" />
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<description>
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Returns the position of the control point leading out of the vertex [param idx]. The returned position is relative to the vertex [param idx]. If the index is out of bounds, the function sends an error to the console, and returns [code](0, 0)[/code].
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</description>
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</method>
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<method name="get_point_position" qualifiers="const">
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<return type="Vector2" />
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<param index="0" name="idx" type="int" />
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<description>
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Returns the position of the vertex [param idx]. If the index is out of bounds, the function sends an error to the console, and returns [code](0, 0)[/code].
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</description>
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</method>
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<method name="remove_point">
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<return type="void" />
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<param index="0" name="idx" type="int" />
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<description>
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Deletes the point [code]idx[/code] from the curve. Sends an error to the console if [code]idx[/code] is out of bounds.
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</description>
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</method>
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<method name="sample" qualifiers="const">
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<return type="Vector2" />
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<param index="0" name="idx" type="int" />
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<param index="1" name="t" type="float" />
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<description>
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Returns the position between the vertex [param idx] and the vertex [code]idx + 1[/code], where [param t] controls if the point is the first vertex ([code]t = 0.0[/code]), the last vertex ([code]t = 1.0[/code]), or in between. Values of [param t] outside the range ([code]0.0 >= t <=1[/code]) give strange, but predictable results.
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If [param idx] is out of bounds it is truncated to the first or last vertex, and [param t] is ignored. If the curve has no points, the function sends an error to the console, and returns [code](0, 0)[/code].
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</description>
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</method>
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<method name="sample_baked" qualifiers="const">
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<return type="Vector2" />
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<param index="0" name="offset" type="float" default="0.0" />
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<param index="1" name="cubic" type="bool" default="false" />
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<description>
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Returns a point within the curve at position [param offset], where [param offset] is measured as a pixel distance along the curve.
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To do that, it finds the two cached points where the [param offset] lies between, then interpolates the values. This interpolation is cubic if [param cubic] is set to [code]true[/code], or linear if set to [code]false[/code].
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Cubic interpolation tends to follow the curves better, but linear is faster (and often, precise enough).
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</description>
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</method>
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<method name="sample_baked_with_rotation" qualifiers="const">
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<return type="Transform2D" />
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<param index="0" name="offset" type="float" default="0.0" />
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<param index="1" name="cubic" type="bool" default="false" />
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<description>
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Similar to [method sample_baked], but returns [Transform2D] that includes a rotation along the curve. Returns empty transform if length of the curve is [code]0[/code].
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[codeblock]
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var transform = curve.sample_baked_with_rotation(offset)
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position = transform.get_origin()
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rotation = transform.get_rotation()
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[/codeblock]
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</description>
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</method>
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<method name="samplef" qualifiers="const">
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<return type="Vector2" />
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<param index="0" name="fofs" type="float" />
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<description>
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Returns the position at the vertex [param fofs]. It calls [method sample] using the integer part of [param fofs] as [code]idx[/code], and its fractional part as [code]t[/code].
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</description>
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</method>
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<method name="set_point_in">
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<return type="void" />
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<param index="0" name="idx" type="int" />
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<param index="1" name="position" type="Vector2" />
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<description>
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Sets the position of the control point leading to the vertex [param idx]. If the index is out of bounds, the function sends an error to the console. The position is relative to the vertex.
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</description>
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</method>
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<method name="set_point_out">
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<return type="void" />
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<param index="0" name="idx" type="int" />
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<param index="1" name="position" type="Vector2" />
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<description>
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Sets the position of the control point leading out of the vertex [param idx]. If the index is out of bounds, the function sends an error to the console. The position is relative to the vertex.
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</description>
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</method>
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<method name="set_point_position">
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<return type="void" />
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<param index="0" name="idx" type="int" />
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<param index="1" name="position" type="Vector2" />
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<description>
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Sets the position for the vertex [param idx]. If the index is out of bounds, the function sends an error to the console.
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</description>
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</method>
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<method name="tessellate" qualifiers="const">
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<return type="PackedVector2Array" />
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<param index="0" name="max_stages" type="int" default="5" />
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<param index="1" name="tolerance_degrees" type="float" default="4" />
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<description>
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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.
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This approximation makes straight segments between each point, then subdivides those segments until the resulting shape is similar enough.
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[param 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!
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[param tolerance_degrees] controls how many degrees the midpoint of a segment may deviate from the real curve, before the segment has to be subdivided.
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</description>
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</method>
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<method name="tessellate_even_length" qualifiers="const">
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<return type="PackedVector2Array" />
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<param index="0" name="max_stages" type="int" default="5" />
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<param index="1" name="tolerance_length" type="float" default="20.0" />
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<description>
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</description>
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</method>
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</methods>
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<members>
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<member name="bake_interval" type="float" setter="set_bake_interval" getter="get_bake_interval" default="5.0">
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The distance in pixels between two adjacent cached points. Changing it forces the cache to be recomputed the next time the [method get_baked_points] or [method 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.
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</member>
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<member name="point_count" type="int" setter="set_point_count" getter="get_point_count" default="0">
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The number of points describing the curve.
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</member>
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</members>
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</class>
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