Method

This node emits particles from an image or video. It can make use of motion vectors to make particles track the motion of a video once emitted. The image or video may be set directly using the Image attribute, or taken from a node connected via the Video Node attribute.
A threshold is applied to the image on either the luminance or alpha channel values as determined by the Pixel Cull/Thickness Mode attribute. Only pixels which pass the threshold are used for emission. If the Use Thickness option is ticked multiple particles may be emitted from each pixel and spread out in depth based on the luminance or alpha value of the pixel, creating volume from the emission. Otherwise, particles may be biased in depth by their luminance using the Luminance Offset Scale parameter, so brighter pixels are pushed forward in 3D space.

The location of emitted particles depends on the way the image is supplied to the emitter. If an image is supplied via the Image attribute or linked from a Video node it will be emitted from a unit plane in the XY axis, combined with the transform from the emitter itself. If an Image Plane node is linked to the emitter’s Video Node input the transform from the Image Plane is used, so the particles will emit at the same location in 3D space as the pixels in the Image Plane, assuming the emitter’s own transform doesn’t offset it. If an Image 2D node is connected, particles use the current camera plane to emit particles such that, after transformation by the camera, they map to the Image 2D node’s pixels in the final render.

Once emitted particles may read the image each frame, sample the colour at their current location and blend towards it by an amount specified by the Image Colour Adaption parameter.

To make particles track video motion a video of motion vectors must be set via the Motion Vector Video parameter; or a node containing motion vectors such as a Video Optical Flow node must be connected to the Motion Video Node input. Input motion vectors are scaled by the Motion Vector Effect attribute.

Example
This image is taken from the “particles_logos_explode.dfx” sample project.

Transform

Name Description
Position X Move its position along the x-axis in local space.
Position Y Move its position along the y-axis in local space.
Position Z Move its position along the z-axis in local space.
Rotation Heading Rotate the object about the x-axis.
Rotation Pitch Rotate the object about the y-axis.
Rotation Bank Rotate the object about the z-axis.
Scale X Scale along the x-axis.
Scale Y Scale along the y-axis.
Scale Z Scale along the z-axis.

Inherit Transform Channels

Toggle which transform channels should be inherited. By default, all are on.

Attributes

Name Description
Image Override the input image with an image selected from the drop down menu.
Flip Image Flip the image input vertically.
Luminance Offset Scale Bias the particles in depth by the luminance of the source pixel.
Use Thickness Toggle whether to emit the particles on a 2d plane, or in three dimensions.
Thickness Change the thickness of the three dimensional area the particles can spawn in. Only functions if “Use Thickness” is on.
Pixel Cull/Thickness Mode Change how the depth of the particle generation is calculated.
  • Alpha Channel, lower alpha values will have greater depth.
  • Luminescence, darker parts of the image will have greater depth.
  • Luminance * Alpha Channel, luminance values are multiplied by alpha values and lower values after which are given greater depth.
Alpha Threshold Limit where the particles will spawn based on their source alpha.
Image Colour Adaption How much the particle colours adapt to the image colours.
Particle Use Image Alpha Toggle whether particles use the image alpha.
Limit Emissions Per Pixel Toggle whether the number of particles that can be emitted per pixel can be limited..
Max Emissions Per Pixel The maximum number of particles that can emit per pixels. Only functions if “Limit Emissions Per Pixel” is true.
Emission Area Min Control the minimum area that the particles will be emitted.
Emission Area Max Control the maximum area that the particles will be emitted.

Emission

Name Description
Emitter Active Change whether the emitter is on or off.
Randomness How much randomness is added in the particles movement.
Life Control how low long each particle exists for.
Life Randomness Control the randomness for the life of each particle.
Emission Rate What percentage of the particles are emitted from the emitter per second.
Max Particle Count Set a maximum particle count for the emitter.
Respawn Enabled Toggle whether a particle can respawn.

Colour Control

To enable, add an input into this node.

Name Description
Colour Selection Mode Choose how the input colour affects the particles.
  • Input Colour, The first colour input is the only colour output.
  • Selected Single Colour, Uses the colour selection parameter to decide which colour to use.
  • Emission Time, Colour is selected based on time at which the particle is emitted.
  • Random Colour, the colour is selected randomly at the particles creation.
Colour Selection Parameters A number used to select the colour output.

Video

Name Description
Depth Video Modifies the z position of the particles, based on the input video.
Motion Vector Video Select a motion vector video to apply to the object.
Motion Vector Effect Scales effect of motion vectors on the motion of the particles.
Motion Vector Scale X Scale particle movement along the x axis.
Motion Vector Scale Y Scale particle movement along the y axis.
Motion Vector Max Maximum movement allowed for the particle.
Motion Vector Bias Control whether there is a bias towards either axis from the motion vector video.
Avi FPS Change the frames per second the video is played at.
Motion Vector FPS Control the frames per second of the input motion video.
Time Offset Offset the time the effect is running.

Material

Name Description
Colour RGB colour of particles.
Diffuse Control how much the light is scattered from the surface of the object.
Emissiveness Control how much light is emitted by the particle.
Life Colour Affecter Weight Controls how much the result of any Life Colour Shading nodes are blended with the particle’s colour.
Particle Scale Scale the size of the particle.
Dof Amount How much depth of field effects the particles material.
Density The density, for use in some simulations.
Temperature The density, for use in some simulations.
Cooling Rate The cooling rate, for thermal dynamics simulations.
Density Decay Control the rate of decay in the density.
Fade In Time What percentage through the particles life span the particle fades in.
Fade Out Time What percentage through the particles life span the particle fades out.

Inputs

Name Description Typical Node Input
Video Node Video used as a basis for the particle system. Video Loader
Motion Video Node Video used to calculate motion for the particles. Optical Flow
Colour Control Nodes Control the colours of the particles. Colour Ramp
Transform Modifier Links all transform properties to the input node. Null
Target Node Always faces the x-axis towards the inputs anchor point. Null
Local Transform Override Override the transformation values of the node, relative to its parent. Null

Outputs

The transformation values of thi node will be inherited by its children. Furthermore, Affectors, Shading And Rendering nodes will only be effective to the particles emit by this emitter.

Notes