Class Link3D

Object

Object3D

GeometryObject

Mesh

Link3D

public class Link3D
extends Mesh

Renderer for thick 3D links. Each link segment is expanded into a small open prism in world coordinates, which gives links a proper depth relationship to spheres and to other links while keeping the appearance unlit and simple.

Author:

Christoph Hauert

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
private static class	Link3D.LinkShader	Minimal unlit shader for world-space link prisms.

Nested classes/interfaces inherited from class Object3D

Object3D.ObjectHandler, Object3D.Traverse

Field Summary

Fields

Modifier and Type	Field	Description
private final Vector3	axis	Temporary storage for the link axis.
private final Vector3	axisHelper	Temporary helper axis used to construct an orthonormal basis around the link axis.
private BufferAttribute	colorAttribute	Per-vertex colors used to support directional gradients.
private static final Color	DEFAULT_COLOR	Fallback color used when link geometry does not provide vertex colors.
private static final int	FACES_PER_LINK	Number of rectangular side faces per link prism.
private int	geometryLinkCount	Number of link segments the current buffers were allocated for.
private static final double	HELPER_AXIS_Z_THRESHOLD	Threshold used when choosing a helper axis for constructing the prism basis.
private double	lineWidth	Current link width in world coordinates.
private int	linkCount	Number of link segments stored in the current geometry.
private Color	linkFallbackColor	Fallback color used when rebuilding links without explicit vertex colors.
private Geometry	linkGeometry	Source line geometry used to rebuild thick-link prisms after width changes.
private static final double	MIN_AXIS_LENGTH2	Smallest admissible squared link length.
private static final double	MIN_LINK_WIDTH	Smallest admissible link width in world coordinates.
private BufferAttribute	positionAttribute	Vertex positions required by the renderer.
private final Vector3	radialU	Temporary first basis vector spanning the prism cross-section.
private final Vector3	radialV	Temporary second basis vector spanning the prism cross-section.
private final ShaderMaterial	shaderMaterial	Material wrapping the custom shader.
private static final int	VERTICES_PER_FACE	Number of triangle vertices used per rectangular side face.
private static final int	VERTICES_PER_LINK	Number of triangle vertices used per link segment.

Fields inherited from class Mesh

__webglMorphTargetInfluences, morphTargetBase, morphTargetForcedOrder, morphTargetInfluences

Fields inherited from class GeometryObject

geometry, material

Fields inherited from class Object3D

__webglActive, __webglInit, _modelViewMatrix, _normalMatrix, children, DefaultUp, handler, id, isCastShadow, isFrustumCulled, isReceiveShadow, matrix, matrixAutoUpdate, matrixWorld, matrixWorldNeedsUpdate, name, parent, position, quaternion, rotation, rotationAutoUpdate, scale, up, visible

Constructor Summary

Constructors

Constructor	Description
Link3D()	Create an empty 3D link mesh.

Method Summary

Modifier and Type	Method	Description
void	clear()	Hide all links from this mesh while keeping the allocated buffers intact.
private BufferAttribute	createAttribute(int vertices, int itemSize)	Create a floating-point buffer attribute.
private void	createGeometry(int links)	Allocate or resize the buffer geometry used for the current link count while keeping the mesh and geometry instances stable.
private void	ensureGeometry(int links)	Ensure that the backing geometry has capacity for the requested link count.
private Color	getVertexColor(List<Color> colors, int index, Color fallbackColor)	Resolve the color for one line vertex.
private void	invalidateGpuBuffers()	Force the renderer to upload fresh GPU buffers for the current attributes.
private void	markGeometryDirty()	Mark all geometry buffers as dirty after an update.
private void	rebuildLinks()	Rebuild the prism geometry from the cached source lines and current width.
void	setLineWidth(double lineWidth)	Set the thickness of the rendered links in world coordinates.
void	setLinks(Geometry lineGeometry)	Update the links rendered by this mesh.
void	setLinks(Geometry lineGeometry, Color fallbackColor)	Update the links rendered by this mesh.
private int	writeFace(int vertexOffset, Vector3 start, Vector3 end, Color startColor, Color endColor, double uA, double vA, double uB, double vB)	Write one rectangular side face of the link prism.
private void	writeLink(int vertexOffset, Vector3 start, Vector3 end, Color startColor, Color endColor)	Write one thick-link prism into the underlying buffers.
private void	writeVertex(int index, double x, double y, double z, Color color)	Write one triangle vertex to the underlying buffers.

Methods inherited from class Mesh

clone, clone, clone, createBuffers, deleteBuffers, initBuffers, raycast, renderBuffer, setBuffers, updateMorphTargets

Methods inherited from class GeometryObject

getGeometry, getMaterial, initCustomAttributes, setGeometry, setLineWidth, setMaterial

Methods inherited from class Object3D

add, add, applyMatrix, clone, clone, getChildren, getChildrenByClass, getId, getMatrix, getMatrixWorld, getName, getObjectById, getObjectByName, getParent, getPosition, getQuaternion, getRenderDepth, getRotation, getScale, getUp, getWorldDirection, getWorldDirection, getWorldPosition, getWorldPosition, getWorldQuaternion, getWorldQuaternion, getWorldRotation, getWorldRotation, getWorldScale, getWorldScale, isCastShadow, isFrustumCulled, isMatrixAutoUpdate, isMatrixWorldNeedsUpdate, isReceiveShadow, isRotationAutoUpdate, isVisible, localToWorld, lookAt, remove, remove, rotateOnAxis, rotateX, rotateY, rotateZ, setCastShadow, setChildren, setFrustumCulled, setHandler, setMatrix, setMatrixAutoUpdate, setMatrixWorld, setMatrixWorldNeedsUpdate, setName, setParent, setPosition, setQuaternion, setReceiveShadow, setRenderDepth, setRotation, setRotationAutoUpdate, setRotationFromAxisAngle, setRotationFromEuler, setRotationFromMatrix, setRotationFromQuaternion, setScale, setUp, setVisible, toString, translateOnAxis, translateX, translateY, translateZ, traverse, traverseVisible, updateMatrix, updateMatrixWorld, worldToLocal

Methods inherited from class Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

FACES_PER_LINK

private static final int FACES_PER_LINK

Number of rectangular side faces per link prism.

See Also:

• Constant Field Values

VERTICES_PER_FACE

private static final int VERTICES_PER_FACE

Number of triangle vertices used per rectangular side face.

See Also:

• Constant Field Values

VERTICES_PER_LINK

private static final int VERTICES_PER_LINK

Number of triangle vertices used per link segment.

See Also:

• Constant Field Values

MIN_LINK_WIDTH

private static final double MIN_LINK_WIDTH

Smallest admissible link width in world coordinates.

See Also:

• Constant Field Values

MIN_AXIS_LENGTH2

private static final double MIN_AXIS_LENGTH2

Smallest admissible squared link length.

See Also:

• Constant Field Values

HELPER_AXIS_Z_THRESHOLD

private static final double HELPER_AXIS_Z_THRESHOLD

Threshold used when choosing a helper axis for constructing the prism basis.

See Also:

• Constant Field Values

DEFAULT_COLOR

private static final Color DEFAULT_COLOR

Fallback color used when link geometry does not provide vertex colors.

positionAttribute

private BufferAttribute positionAttribute

Vertex positions required by the renderer.

colorAttribute

private BufferAttribute colorAttribute

Per-vertex colors used to support directional gradients.

shaderMaterial

private final ShaderMaterial shaderMaterial

Material wrapping the custom shader.

axis

private final Vector3 axis

Temporary storage for the link axis.

axisHelper

private final Vector3 axisHelper

Temporary helper axis used to construct an orthonormal basis around the link axis.

radialU

private final Vector3 radialU

Temporary first basis vector spanning the prism cross-section.

radialV

private final Vector3 radialV

Temporary second basis vector spanning the prism cross-section.

linkCount

private int linkCount

Number of link segments stored in the current geometry.

geometryLinkCount

private int geometryLinkCount

Number of link segments the current buffers were allocated for.

lineWidth

private double lineWidth

Current link width in world coordinates.

linkGeometry

private Geometry linkGeometry

Source line geometry used to rebuild thick-link prisms after width changes.

linkFallbackColor

private Color linkFallbackColor

Fallback color used when rebuilding links without explicit vertex colors.

Constructor Details

Link3D

public Link3D()

Create an empty 3D link mesh.

Method Details

setLinks

public void setLinks(Geometry lineGeometry)

Update the links rendered by this mesh.

Parameters:

lineGeometry - the geometry containing link endpoints and optional colors

setLinks

public void setLinks(Geometry lineGeometry,
 Color fallbackColor)

Update the links rendered by this mesh.

Parameters:

lineGeometry - the geometry containing link endpoints and optional colors

fallbackColor - the color to use when vertex colors are absent

clear

public void clear()

Hide all links from this mesh while keeping the allocated buffers intact.

setLineWidth

public void setLineWidth(double lineWidth)

Set the thickness of the rendered links in world coordinates.

Parameters:

lineWidth - the desired link width

rebuildLinks

private void rebuildLinks()

Rebuild the prism geometry from the cached source lines and current width.

createGeometry

private void createGeometry(int links)

Allocate or resize the buffer geometry used for the current link count while keeping the mesh and geometry instances stable.

Parameters:

links - the number of link segments

ensureGeometry

private void ensureGeometry(int links)

Ensure that the backing geometry has capacity for the requested link count.

Parameters:

links - the number of link segments to render

invalidateGpuBuffers

private void invalidateGpuBuffers()

Force the renderer to upload fresh GPU buffers for the current attributes. Parallax caches WebGL buffers behind each attribute, so dynamic link updates must invalidate those handles explicitly.

createAttribute

private BufferAttribute createAttribute(int vertices,
 int itemSize)

Create a floating-point buffer attribute.

Parameters:

vertices - the number of vertices

itemSize - the number of components per vertex

Returns:

the new attribute

writeLink

private void writeLink(int vertexOffset,
 Vector3 start,
 Vector3 end,
 Color startColor,
 Color endColor)

Write one thick-link prism into the underlying buffers.

Parameters:

vertexOffset - the first vertex index of the segment

start - the segment start position

end - the segment end position

startColor - the color at the start point

endColor - the color at the end point

writeFace

private int writeFace(int vertexOffset,
 Vector3 start,
 Vector3 end,
 Color startColor,
 Color endColor,
 double uA,
 double vA,
 double uB,
 double vB)

Write one rectangular side face of the link prism.

Parameters:

vertexOffset - the first vertex index of the face

start - the segment start position

end - the segment end position

startColor - the color at the start point

endColor - the color at the end point

uA - the first corner coefficient along radialU

vA - the first corner coefficient along radialV

uB - the second corner coefficient along radialU

vB - the second corner coefficient along radialV

Returns:

the next free vertex index

writeVertex

private void writeVertex(int index,
 double x,
 double y,
 double z,
 Color color)

Write one triangle vertex to the underlying buffers.

Parameters:

index - the vertex index

x - the x-coordinate

y - the y-coordinate

z - the z-coordinate

color - the vertex color

getVertexColor

private Color getVertexColor(List<Color> colors,
 int index,
 Color fallbackColor)

Resolve the color for one line vertex.

Parameters:

colors - the optional color array

index - the vertex index

fallbackColor - the color to use when no explicit value exists

Returns:

the selected color

markGeometryDirty

private void markGeometryDirty()

Mark all geometry buffers as dirty after an update.