SplineGraph Class

WarningThe scope of applications for UnigineScript is limited to implementing materials-related logic (material expressions, scriptable materials, brush materials). Do not use UnigineScript as a language for application logic, please consider C#/C++ instead, as these APIs are the preferred ones. Availability of new Engine features in UnigineScript (beyond its scope of applications) is not guaranteed, as the current level of support assumes only fixing critical issues.

This class is used to manage vertices and segments of spline graphs. UNIGINE's 3D spline system has a wide range of applications, particularly procedural content generation (rivers, roads, pipelines etc.).

A spline graph is determined by a set of points p₀, p ₁, ... p _n and a set of segments (cubic Bezier splines), that connect some or all of these points.

Each segment is determined by the indices of the starting (p_START ) and ending (p_END ) points and tangent vector coordinates at these points, which determine the form of the segment (t_START and t_END respectively).

Coordinates of the "up" vector are additionally stored for each point of the segment. You can specify this vector to define orientation of geometry or objects, that can be stretched or tiled along the segments of the spline graph. By default this vector is parallel to the Z axis. The "up" vector does not affect the form of the spline segment.

It is possible to obtain an interpolated value for any point belonging to a segment, this can be used for various purposes (e.g. to change road profile). Interpolated "up" vector can be calculated as follows (pseudocode):

Source code (C++)

vec3 lerpUpVector(vec3 start_up, vec3 end_up, float t) const
{
	float angle = acos(dot(start_up, end_up)) * RAD2DEG;
	vec3 rotation_axis = cross(start_up, end_up);

	return rotateAxisAngle(rotation_axis, angle * t) * start_up;
}

Methods:

Name	Description View: Sort by:
SplineGraph	Default constructor.
getNumPoints	Returns the total number of points in the spline graph.
getNumSegments	Returns the total number of segments in the spline graph.
getLength	Returns the length of the segment with a given index.
setPoint	Sets new coordinates for the point with a given index.
getPoint	Returns the coordinates of the point with a given index.
setSegmentEndPoint	Sets the coordinates of the end point for the segment with a given index.
getSegmentEndPoint	Returns the coordinates of the end point for the segment with a given index.
getSegmentEndPointIndex	Returns the index of the end point for the segment with a given index.
setSegmentEndTangent	Sets the tangent coordinates for the end point of the segment with a given index.
getSegmentEndTangent	Returns the tangent coordinates for the end point of the segment with a given index.
setSegmentEndUpVector	Sets the "up" vector coordinates for the end point of the segment with a given index.
getSegmentEndUpVector	Returns the "up" vector coordinates for the end point of the segment with a given index.
setSegmentStartPoint	Sets the coordinates of the start point for the segment with a given index.
getSegmentStartPoint	Returns the coordinates of the start point for the segment with a given index.
getSegmentStartPointIndex	Returns the index of the end point for the segment with a given index.
setSegmentStartTangent	Sets the tangent coordinates for the start point of the segment with a given index.
getSegmentStartTangent	Returns the tangent coordinates for the start point of the segment with a given index.
setSegmentStartUpVector	Sets the "up" vector coordinates for the start point of the segment with a given index.
getSegmentStartUpVector	Returns the "up" vector coordinates for the start point of the segment with a given index.
addPoint	Adds a point with specified coordinates to the spline graph.
addSegment	Adds a segment to the spline graph.
calcSegmentPoint	Returns the coordinates of the point at the parametrically specified position on the segment (along the T axis).
calcSegmentTangent	Returns the tangent coordinates for the point at the parametrically specified position on the segment (along the T axis).
calcSegmentUpVector	Returns the "up" vector coordinates for the point at the parametrically specified position on the segment (along the T axis).
clear	Clears the spline graph.
load	Loads the spline graph from the specified XML-file.
removePoint	Removes a point with a given index from the spline graph.
splitPoint	Splits the point with the specified index into N points, where N is the number of segments attached to the point.
weldPoints	Merges all points with given indices into one.
removeSegment	Removes the segment with a given index.
save	Saves the spline graph to the specified XML-file.
insertPointToSegment	Inserts a new point into the given segment.
getPointSegmentsIndices	Retrieves indices of all segments attached to the specified point and puts them to the given index buffer.

SplineGraph Class

Members

static SplineGraph ( ) #

Default constructor. Creates an empty spline graph.

static SplineGraph ( string name ) #

Constructor. Creates an empty spline graph with a given name.

Arguments

string name - Spline graph name.

float getLength ( int index ) #

Returns the length of the segment with a given index.

Arguments

int index - Segment index.

Return value

Segment length.

Arguments

int index - Segment index.
vec3 tangent - End point tangent coordinates.

vec3 getSegmentEndTangent ( int index ) #

Returns the tangent coordinates for the end point of the segment with a given index.

Arguments

int index - Segment index.

Return value

End point tangent coordinates.

void setSegmentEndUpVector ( int index, vec3 up ) #

Sets the "up" vector coordinates for the end point of the segment with a given index.

Arguments

int index - Segment index.
vec3 up - End point "up" vector coordinates.

vec3 getSegmentEndUpVector ( int index ) #

Returns the "up" vector coordinates for the end point of the segment with a given index.

Arguments

int index - Segment index.

Return value

End point "up" vector coordinates.

void setSegmentStartPoint ( int index, Vec3 point ) #

Sets the coordinates of the start point for the segment with a given index.

Arguments

int index - Segment index.
Vec3 point - Segment start point coordinates to be set.

Vec3 getSegmentStartPoint ( int index ) #

Returns the coordinates of the start point for the segment with a given index.

Arguments

int index - Segment index.

Return value

Segment start point coordinates.

int getSegmentStartPointIndex ( int index ) #

Returns the index of the end point for the segment with a given index.

Arguments

int index - Segment index.

Return value

Segment start point index.

void setSegmentStartTangent ( int index, vec3 tangent ) #

Sets the tangent coordinates for the start point of the segment with a given index.

Arguments

int index - Segment index.
vec3 tangent - Start point tangent coordinates.

vec3 getSegmentStartTangent ( int index ) #

Returns the tangent coordinates for the start point of the segment with a given index.

Arguments

int index - Segment index.

Return value

Start point tangent coordinates.

void setSegmentStartUpVector ( int index, vec3 up ) #

Sets the "up" vector coordinates for the start point of the segment with a given index.

Arguments

int index - Segment index.
vec3 up - Start point "up" vector coordinates.

vec3 getSegmentStartUpVector ( int index ) #

Returns the "up" vector coordinates for the start point of the segment with a given index.

Arguments

int index - Segment index.

Return value

Start point "up" vector coordinates.

int addPoint ( Vec3 point ) #

Adds a point with specified coordinates to the spline graph.

Arguments

Vec3 point - Point coordinates.

Return value

Current number of points in the spline graph.

int addSegment ( int start_index, vec3 start_tangent, vec3 start_up, int end_index, vec3 end_tangent, vec3 end_up ) #

Adds a segment to the spline graph.

Arguments

int start_index - Start point index.
vec3 start_tangent - Start point tangent coordinates.
vec3 start_up - Start point "up" vector coordinates.
int end_index - End point index.
vec3 end_tangent - End point tangent coordinates.
vec3 end_up - End point "up" vector coordinates.

Return value

Number of segments in the spline graph if a segment was adds successfully; otherwise, -1

Vec3 calcSegmentPoint ( int index, float t ) #

Returns the coordinates of the point at the parametrically specified position on the segment (along the T axis).

Arguments

int index - Segment index.
float t - Position of the point on the segment, specified parametrically along the T (times axis) in the [0.0f, 1.0f] range.

Return value

Coordinates of the point on the given segment.

vec3 calcSegmentTangent ( int index, float t ) #

Returns the tangent coordinates for the point at the parametrically specified position on the segment (along the T axis).

Arguments

int index - Segment index.
float t - Position of the point on the segment, specified parametrically along the T (times axis) in the [0.0f, 1.0f] range.

Return value

Tangent coordinates for the point on the given segment.

vec3 calcSegmentUpVector ( int index, float t ) #

Returns the "up" vector coordinates for the point at the parametrically specified position on the segment (along the T axis).

Arguments

int index - Segment index.
float t - Position of the point on the segment, specified parametrically along the T (times axis) in the [0.0f, 1.0f] range.

Return value

"Up" vector coordinates for the point on the given segment.

void clear ( ) #

Clears the spline graph.

int load ( string name ) #

Loads the spline graph from the specified XML-file.

Arguments

string name - Name of the XML-file to load the spline graph from.

Return value

1 if the spline graph was successfully loaded; otherwise, 0.

void removePoint ( int index, int merge = 0 ) #

Removes a point with a given index from the spline graph.

Arguments

int index - Point index.
int merge - Merge flag. When there are two segments attached to the point, use 1 to merge these segments into one; 0 removes all segments attached to the point (by default).

void splitPoint ( int index ) #

Splits the point with the specified index into N points, where N is the number of segments attached to the point. The number of points in the graph shall increase by N-1. All new points will be attached to the corresponding segments.

Arguments

int index - Point index.

void weldPoints ( Vector<int>& indices ) #

Merges all points with given indices into one.

NoticeAll common segments between these points shall be removed. All points with given indices are removed from the graph, except for the one having the minimum index value, all segments shall be attached to this point. Resulting point shall be moved to the position of the first point in the given array.

Arguments

Vector<int>& indices - Array containing indices of points to be merged into one.

void removeSegment ( int index, int with_points = 0 ) #

Removes the segment with a given index.

Arguments

int index - Segment index.
int with_points - Use 1 to remove segment with its starting and ending points, or 0 to remove the segment only.
Notice
Points will be removed only in case if they do not belong to other segments. After removal, the last element of the vector of spline graph segments shall be moved to the position of the one removed.

int save ( string name ) #

Saves the spline graph to the specified XML-file.

Arguments

string name - Name of the XML-file to save the spline graph to.

Return value

1 if the spline graph was successfully saved; otherwise, 0.

void insertPointToSegment ( int segment_index, float new_point_t ) #

Inserts a new point into the given segment. The point is parametrically specified on the T (times axis) in the [0.0f, 1.0f] range from the segment's start point.

Arguments

int segment_index - Segment index.
float new_point_t - Coordinate of the new point to be added along the horizontal T (times) axis in the range [0.0f, 1.0f].

void getPointSegmentsIndices ( int index, Vector<int>& indices ) #

Retrieves indices of all segments attached to the specified point and puts them to the given index buffer.

Arguments

int index - Point index.
Vector<int>& indices - Index buffer to which segment indices will be added.

Last update: 2021-12-13

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SplineGraph Class

See Also#

Methods:

SplineGraph Class

Members

static SplineGraph ( ) #

static SplineGraph ( string name ) #

Arguments

float getLength ( int index ) #

Arguments

Return value

int getNumPoints ( ) #

Return value

int getNumSegments ( ) #

Return value

void setPoint ( int index, Vec3 point ) #

Arguments

Vec3 getPoint ( int index ) #

Arguments

Return value

void setSegmentEndPoint ( int index, Vec3 point ) #

Arguments

Vec3 getSegmentEndPoint ( int index ) #

Arguments

Return value

int getSegmentEndPointIndex ( int index ) #

Arguments

Return value

void setSegmentEndTangent ( int index, vec3 tangent ) #

Arguments

vec3 getSegmentEndTangent ( int index ) #

Arguments

Return value

void setSegmentEndUpVector ( int index, vec3 up ) #

Arguments

vec3 getSegmentEndUpVector ( int index ) #

Arguments

Return value

void setSegmentStartPoint ( int index, Vec3 point ) #

Arguments

Vec3 getSegmentStartPoint ( int index ) #

Arguments

Return value

int getSegmentStartPointIndex ( int index ) #

Arguments

Return value

void setSegmentStartTangent ( int index, vec3 tangent ) #

Arguments

vec3 getSegmentStartTangent ( int index ) #

Arguments

Return value

void setSegmentStartUpVector ( int index, vec3 up ) #

Arguments

vec3 getSegmentStartUpVector ( int index ) #

Arguments

Return value

int addPoint ( Vec3 point ) #

Arguments

Return value

int addSegment ( int start_index, vec3 start_tangent, vec3 start_up, int end_index, vec3 end_tangent, vec3 end_up ) #

Arguments

Return value

Vec3 calcSegmentPoint ( int index, float t ) #

Arguments

Return value

vec3 calcSegmentTangent ( int index, float t ) #

Arguments

Return value

vec3 calcSegmentUpVector ( int index, float t ) #

Arguments

Return value

void clear ( ) #

int load ( string name ) #

Arguments

Return value

void removePoint ( int index, int merge = 0 ) #

Arguments

void splitPoint ( int index ) #

Arguments

void weldPoints ( Vector<int>& indices ) #