Unigine.SplineGraph Class

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, p₁, ... 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):

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;
}

See Also

SplineGraph Class

Members

static SplineGraph()

static SplineGraph(string name)

Arguments

• string name - Spline graph name.

static SplineGraph(SplineGraph graph)

Arguments

• SplineGraph graph - Source spline graph.

float getLength(int index)

Arguments

• int index - Segment index.

Return value

int getNumPoints()

Return value

int getNumSegments()

Return value

void setPoint(int index, vec3 point)

Arguments

• int index - Point index.
• vec3 point - New point coordinates.

vec3 getPoint(int index)

Arguments

• int index - Point index.

Return value

vec3 getSegmentEndPoint(int index)

Arguments

• int index - Segment index.

Return value

int getSegmentEndPointIndex(int index)

Arguments

• int index - Segment index.

Return value

void setSegmentEndTangent(int index, vec3 tangent)

Arguments

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

vec3 getSegmentEndTangent(int index)

Arguments

• int index - Segment index.

Return value

void setSegmentEndUpVector(int index, vec3 up)

Arguments

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

vec3 getSegmentEndUpVector(int index)

Arguments

• int index - Segment index.

Return value

vec3 getSegmentStartPoint(int index)

Arguments

• int index - Segment index.

Return value

int getSegmentStartPointIndex(int index)

Arguments

• int index - Segment index.

Return value

void setSegmentStartTangent(int index, vec3 tangent)

Arguments

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

vec3 getSegmentStartTangent(int index)

Arguments

• int index - Segment index.

Return value

void setSegmentStartUpVector(int index, vec3 up)

Arguments

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

vec3 getSegmentStartUpVector(int index)

Arguments

• int index - Segment index.

Return value

int addPoint(vec3 point)

Arguments

• vec3 point - Point coordinates.

Return value

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

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

vec3 calcSegmentPoint(int index, float t)

Arguments

• int index - Segment index.
• float t - Position of the point on the segment, in increments of the segment's length normalized to 1.

Return value

vec3 calcSegmentTangent(int index, float t)

Arguments

• int index - Segment index.
• float t - Position of the point on the segment, in increments of the segment's length normalized to 1.

Return value

vec3 calcSegmentUpVector(int index, float t)

Arguments

• int index - Segment index.
• float t - Position of the point on the segment, in increments of the segment's length normalized to 1.

Return value

void clear()

int load(string name)

Arguments

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

Return value

void removePoint(int index)

Arguments

• int index - Point index.

void removeSegment(int index)

Arguments

• int index - Segment index.

int save(string name)

Arguments

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

Return value