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PointAlongPath

Header:	AVL.h
Namespace:	avl
Module:	FoundationLite

Transforms a point to a coordinate system in which the 'axis' path is vertical or horizontal.

Applications: Usually used to revert an ImageAlongPath transformation.

Syntax

void avl::PointAlongPath
(
	const avl::Point2D& inPoint,
	const avl::Path& inAxis,
	avl::Axis::Type inAxisType,
	float inAxisCoordinate,
	bool inInverse,
	avl::Point2D& outPoint
)

Parameters

Name	Type	Default	Description
inPoint	const Point2D&		Input point
inAxis	const Path&		Input axis path
inAxisType	Axis::Type	Y	Type of axis the input axis path is parallel to
inAxisCoordinate	float	0.0f	Coordinate of the axis path
inInverse	bool	True	Switches to the inverse operation
outPoint	Point2D&		Transformed point

Description

This operation transforms a point - inPoint - between two coordinate systems: the one linked with 'axis' path inAxis and the original one. Direction of this conversion is based on inInverse value:

if it is true, inPoint is converted to original coordinate system
if it is false, inPoint is converted from original coordinate system

Coordinate system linked with inAxis is some transformation of the original one, satisfying these conditions:

'axis' path is represented as a straight line
'axis' path is horizontal if inAxisType is set to X or vertical if inAxisType is set to Y
if inAxisType is set to X, the Y coordinate of 'axis' path is equal to inAxisCoordinate. If inAxisType is set to Y, the X coordinate of 'axis' path is equal to inAxisCoordinate

Hints

If this filter is used to reverse ImageAlongPath transformation you should set inAxis and inAxisType to the same values as corresponding ones in ImageAlongPath. inAxisCoordinate should be set to a half of ImageAlongPath.inScanWidth.

Examples

ImageAlongPath performed on the sample image with inAxisType = X, inScanWidth = 50 and path marked with blue. Point marked with blue cross on the output image was calculated by ScanSingleEdge. Original point (marked with orange cross) was calculated using PointAlongPath with inAxisType = X, inAxisCoordinate = 25, inInverse = true and position of detected point. ImageAlongPath and PointAlongPath used the same path for transformations.

Errors

List of possible exceptions:

Error type	Description
DomainError	Empty path on input in PointAlongPath.