Post

ParticleSystem

Posted Updated
By CREATE3000
8 min read
ParticleSystem

Overview

ParticleSystem specifies a complete particle system. It can contain Appearance for particle appearance, a geometry node if geometryType=’GEOMETRY’, a color field with Color or ColorRGBA node for changing base color over each particle’s lifetime, a texcoord TextureCoordinate node to control texture coordinates of provided texture(s) in the Appearance node over time, a single emitter X3DParticleEmitterNode, and an array of physics X3DParticlePhysicsModelNode nodes.

The ParticleSystem node belongs to the ParticleSystems component and requires at least level 2, its default container field is children. It is available from X3D version 3.2 or higher.

Hierarchy

1
2
3
4

+ X3DNode
  + X3DChildNode
    + X3DShapeNode (X3DBoundedObject)*
      + ParticleSystem

* Derived from multiple interfaces.

Fields

SFNode [in, out] metadata NULL [X3DMetadataObject]

Information about this node can be contained in a MetadataBoolean, MetadataDouble, MetadataFloat, MetadataInteger, MetadataString or MetadataSet node.

Hint

SFBool [in, out] enabled TRUE

Enables/disables node operation.

SFBool [in, out] createParticles TRUE

Enables/disables creation of new particles, while any existing particles remain in existence and continue to animate until the end of their lifetimes.

Hint

  • If no particles are left in scene, system is considered both active and enabled.

SFString [ ] geometryType “QUAD” [“LINE”|”POINT”|”QUAD”|”SPRITE”|”TRIANGLE”|”GEOMETRY”|…]

Specifies type of geometry used to represent individual particles. Typically, a particle is calculated as point in space at which the geometry is placed. Changing the value of the geometry field or the definition of the geometry node shall be applied during current computation of the next frame to be rendered.

Hints

  • LINE means that a line is drawn along the particle’s current velocity vector, for this frame, centered about the particle’s position. The length of the line is specified by the particle’s height from the particleSize field value.
  • POINT means that a point geometry is rendered at the particle’s position.
  • QUAD means that a 2D quad is rendered aligned in the local coordinate space of the particle system with the face normal pointing along the positive Z axis. Individual quads are not aligned to the user’s eye position but are affected in depth by the physics model. The particle’s position is at the center of the quad.
  • SPRITE means that a point sprite that uses a 2D point position to locate a screen-aligned quad at the center of the particle’s location is rendered.
  • TRIANGLE means that a 2D quad is rendered using a pair of triangles aligned in the local coordinate space of the particle system with the face normal pointing along the positive Z axis. Individual triangles are not aligned to the user’s eye position, but are affected in depth by the physics model. The particle’s position is at the center of the triangle.
  • GEOMETRY means that the geometry specified by the geometry field is rendered for each particle using the local coordinate system.
  • X3D for Advanced Modeling (X3D4AM) slideset

Warnings

  • Do not wrap extra quotation marks around these SFString enumeration values, since “quotation” “marks” are only used for MFString values.
  • Requires X3D profile='Full' or else include <component name='Geospatial' level='1'/>

SFInt32 [in, out] maxParticles 200 [0,∞)

Maximum number of particles to be generated at one time (subject to player limitations).

SFFloat [in, out] particleLifetime 5 [0,∞)

TODO not properly defined in X3D specification. Particle animation lifetime in base time units (default is seconds).

SFFloat [in, out] lifetimeVariation 0.25 [0,1]

TODO not properly defined in X3D specification. Multiplier for the randomness used to control the range of possible output values. The bigger the value, the more random the output and the bigger the range of initial values possible.

Hint

  • Variation of zero does not allow any randomness.

SFVec2f [in, out] particleSize 0.02 0.02 [0,∞)

particleSize describes width and height dimensions for each particle in length base units (default is meters). Changing this value dynamically will only change new particles created after the change.

Hints

  • Particles created before this timestamp will remain at the old size.
  • His field only effects particles using LINE, QUAD, SPRITE, and TRIANGLE geometry types.

SFNode [ ] emitter NULL [X3DParticleEmitterNode]

The emitter field specifies the type of emitter geometry and properties that the particles are given for their initial positions.

MFNode [ ] physics [ ] [X3DParticlePhysicsModelNode]

After being created, the individual particles are then manipulated according to the physics model(s) specified in the physics field.

MFFloat [ ] colorKey [ ] [0,∞)

Array of time intervals in seconds, corresponding to particle lifetime, that are used to interpolate color array values.

Hints

Warning

  • If an Appearance and Material nodes are provided, those material properties override color field interpolation.

SFNode [ ] color NULL [X3DColorNode]

The color field contains Color or ColorRGBA nodes as a series of color values to be used at the given colorKey points in time.

Hints

  • color values are defined as per-vertex color values.
  • Number of colorKey values must match length of the per-vertex color field array values!
  • X3D Scene Authoring Hints, Color

Warnings

MFFloat [ ] texCoordKey [ ] [0,∞)

Array of time intervals in seconds, corresponding to particle lifetime, that are used to sequence texCoord array values.

Hints

  • No interpolation is performed, texture coordinates are simply sequenced in order.
  • Texture-coordinate values map textures to vertices in the geometry.
  • Number of texCoordKey values must match length of the per-vertex texCoord arrays!

SFNode [ ] texCoord NULL [TextureCoordinate]

Texture coordinates of the provided texture(s) in the Appearance node, over time. Particle systems frequently like to change the texture on a particle as it ages, yet there is no good way of accomplishing this through standard interpolators because interpolators have no concept of particle time. This pair of fields hold time-dependent values for the texture coordinates to be applied to the particle. When a particle reaches the next time stamp it moves to the next set of texture coordinates.

Hints

  • Texture-coordinate values map textures to vertices in the geometry.
  • Number of texCoordKey values must match length of the per-vertex texCoord arrays!

Warning

SFBool [out] isActive

isActive true/false events are sent when playback starts/stops.

Warning

  • It is an error to define this transient outputOnly field in an X3D file, instead only use it a source for ROUTE events.

SFBool [in, out] pointerEvents TRUE non standard

pointerEvents defines whether this Shape becomes target for pointer events.

SFBool [in, out] castShadow TRUE

The castShadow field defines whether this Shape casts shadows as produced by lighting nodes.

Hints

  • If the visible field is FALSE, then the Shape does not cast any shadows, regardless of the castShadow value.
  • If prior X3D3 content is loaded into an X3D4 model, then legacy Shape nodes have shadows set to true.

SFBool [in, out] visible TRUE

Whether or not renderable content within this node is visually displayed.

Hints

  • The visible field has no effect on animation behaviors, event passing or other non-visual characteristics.
  • Content must be visible to be collidable and to be pickable.

SFBool [in, out] bboxDisplay FALSE

Whether to display bounding box for associated geometry, aligned with world coordinates.

Hint

  • The bounding box is displayed regardless of whether contained content is visible.

SFVec3f [ ] bboxSize -1 -1 -1 [0,∞) or −1 −1 −1

Bounding box size is usually omitted, and can easily be calculated automatically by an X3D player at scene-loading time with minimal computational cost. Bounding box size can also be defined as an optional authoring hint that suggests an optimization or constraint.

Hints

SFVec3f [ ] bboxCenter 0 0 0 (-∞,∞)

Bounding box center accompanies bboxSize and provides an optional hint for bounding box position offset from origin of local coordinate system.

Hints

SFNode [in, out] appearance NULL [X3DAppearanceNode]

The appearance field holds an Appearance node that is used for the geometry. All effects, such as material colors and/or multi-textures, are applied to each particle.

Hints

  • If a texture coordinate ramp and key is supplied with this geometry, it shall be used in preference to any automatic texture coordinate generation.
  • If automatic texture coordinate generation is used, results shall be based on the entire volume that the particles consume, not locally applied to each particle.

SFNode [in, out] geometry NULL [X3DGeometryNode]

Single contained geometry node provides geometry used for each particle when geometryType=GEOMETRY.

Hint

Warning

  • Requires X3D profile='Full' or else include <component name='Geospatial' level='1'/>

Advice

  • Always set bboxSize and boxCenter correctly; bboxSize and bboxCenter cannot be determined automatically, so it’s up to the author to provide the correct values.

Hints

Example

See Also

components, ParticleSystems
ParticleSystem ParticleSystems
This post is licensed under CC BY 4.0 by the author.

ParticleSystems