Method

This node renders particles onto nearby 3D surfaces. This means that instead of rendering particles directly into space, they instead appear as splats on 3D geometry, only being visible when they are close enough to 3D geometry. This is particularly useful when attempting to render particles in a scene rendered by a UV Camera.

For this node to be effective, Deferred Rendering must be enabled in the Root Node. There must be visible opaque 3D geometry in the scene, and the particles must be close enough to geometry to intersect with it in order to be rendered.

The Blend Mode parameter is used to control the blend mode between individual particles and also between the particles and the rest of the scene. The Particle Alpha parameter can be used to control the transparency of individual particles, scaling the alpha value already on the particle’s colour channel.

The particle size may be controlled by the Particle Size and Particle X and Y Scale parameters, which are multiplied with the scale on the particle’s emitter material. The scale can be randomised using the Size Randomness parameter. The Scale Over Time control can be used to make the particle grow or shrink over its life time. The Scale / Alpha Mode control can be used to additionally scale particles by the alpha value of their colour channel, allowing Shading nodes to have an effect on the scale of particles by modifying the alpha. Particles are usually camera-aligned so sprites are always oriented to the view direction but the Alignment parameter may be used to orient them along the particle’s normal direction instead. The 2D rotation of sprites may be controlled by the Rotation and Rotation Randomness parameters.

An image may be used on the particle. It can be set via the Texture parameter, or via a Video Node connected to the Image Node input. If an image is not used the sprites will render as plain rectangles. The alpha channel of the image is used to affect particle transparency. So that animations can be played on each particle or so that each particle can use a different image, it is possible to treat the image as multiple frames laid out within the texture. The Texture Animation parameters control this. If Use Texture Animation is enabled, the image is considered to be a series of frames laid out in a regular grid of cells defined by Num Frames X and Num Frames Y. Each particle then plays the animation frames sequentially at a rate defined by Texture Animation Rate, with loop points set by Texture Animation End Frame and Texture Animation Loop Frame. The Texture Start Frame Mode parameter is used to determine how the start frame of the animation is chosen per particle: from the start, from a random frame, or using the particle’s emission sequence or emitter. If the Texture Animation Rate is set to 0 and a random start frame is used, each particle will use a different static frame of the texture but no animation will occur.

Motion blur effects may be simulated on particles in an efficient way using the Motion Blur Amount parameter, which causes sprites to be stretched along their direction of motion. Depth of field may be simulated by blurring and enlarging the sprites further away from the camera focus plane.

Example

Attributes

Name Description
Texture Select a texture to be rendered at each particles position.
Particle Size Edit the size of the particles once they are rendered.
Particle X Scale Control the x-scale of the sprites emitted.
Particle Y Scale Control the x-scale of the sprites emitted.
Pixel Align Output Align the rendered points exactly to screen pixels, with no sub-pixel interpolation.
Particle Scale Coeffs How much the particle scales are affected by the node at different stages of the particles life cycle. Values 1 and 2 are control points, and are used to control the curve between values 0 and 3.
Particle Alpha Change the alpha value for the particles.
Visible Control whether the node is visible or not to the scene.
Size Randomness Control the randomness in size of the particles.
Rotation Randomness Give the meshes a randomised rotation.
Luminance Randomness Control how much randomness is in the luminance of the rendered particles.
Screen Size Limits The minimum and maximum size of the rendered particle in normalised screen coordiates.
Specify Size Limits In Pixels Indicates whether particle size limits are specified in normalised viewport coordinates which are consistent across different render resolutions, or in pixels.
Sort Key Value Biases the depth-based render order, to force the particle system to be drawn before or after other objects in the scene.
Depth Bias Offsets particles in depth so they are closer or further away from the camera, changing the point at which they intersect with the rest of the scene.
Motion Blur Amount Control the amount of motion blur.
Use Texture Animation Edit whether the texture animation is shown with the rendering.
Texture Animation Rate Edit whether the texture animation is shown with the rendering.
Num Frames X Change how many tiles the sprite image will be spread across the x axis.
Num Frames Y Change how many tiles the sprite image will be spread across the y axis.
Randomise Start Frame Randomises the beginning frame the texture animation is played from.
Blend Mode Choose how the particle colours blend to the source colours
Rotation Follows Direction Toggle whether the rotation of the particles follows the direction the particle is moving in.
Output Target Determines which channel the effect is rendered to.
  • Composite, Render particles to the final composite colour channel.
  • Baked Shadow, Render particles to the shadow channel, so they appear as shadows that darken the effect of lights on geometry.
  • Albedo, Render particles to the albedo colour channel so they appear as decals, with lighting applied on top.

Inputs

Name Description Typical Node Input
Bounds Node The bounding box within which particles are rendered. Bounding Box
Rendered Emitters Specify which emitters are rendered using this renderer. By default, all emitters connected to the same particle root as the renderer are rendered. Primitive Emitter
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 outputs section for this node is currently being worked on.