#### Please see Using the Particles Effect section in the OpenToonz Manual to obtain detailed information.

Particles Effect List of Parameters
Page | Category | Param Name | Description | Control Image
Source | Source | (Control Image) | Particles are generated evenly in areas where the opacity of the Control image is greater than or equal to Threshold. If there is no Control image cell in the current frame or if the overall opacity of it is less than Threshold, the result will be the same as when there is no Control image connected. | ○
|  | Threshold | Threshold to be used in the above image for deciding where to generate particles (0-255). |

Multiple Generators in Control Image

Applies for when there are multiple opaque areas (hereinafter “sources”) in the Control image, surrounded by transparent areas.
When ON: The amount of generated particles is equalized for each source. That is, the narrower the generation source, the higher the particle generation density there.
When OFF: The density of generated particles is uniform throughout the whole Source image. That is, the amount of particles decreases as each source area becomes narrower.

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|  | Use Control Image Gradation | The particle generation density is changed in proportion to the opacity of the Source image. This option is not compatible with the Multiple Generators in Control Image above. | ―
|  | Center X | X coordinate of the Center position of the particle generation area, when there is no input image. | ―
|  | Center Y | Y coordinate of the Center position of the particle generation area, when there is no input image. | ―
|  | Width | The width of the particle generation area (a rectangle), when there is no input image. | ―
|  | Height | The height of the particle generation area (a rectangle), when there is no input image. | ―
| Particle Generation | Starting Frame | The scene frame when particles starts to be generated. Negative values are also possible. | ―
|  | Birth Rate | Number of particles generated in every frame. | ―
|  | Animation Step | Particle animation Step value. *If this Step value is set to 2 or more, the Step of picture change specified in Particle → Animation will be the square of the set value. | ―
|  | Random Seed | Seed value of random parameters used in this effect. | ―

Particle

Animation

Hold Frame: The start frame determined randomly from each cell of the Source Column (not Level) is fixed as it is.
Random Frame: The frame used changes randomly by the square of the above AnimationStep value.
Column: Frame used in each particle changes in the same order of the cells in the Source Column. Starting from the first frame.
Column - Random Start: Frame used in each particle changes in the same order of the cells in the Source Column. Starting from a random frame.
Column Swing - Random Start: Frame used in each particle changes in the same order of the cells in the Source Column, reverses playback when reaching the end. Starting from a random frame.

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Page | Category | Param Name | Description | Control Image
Birth Params | Speed | Speed | Initial velocity of particles. | ○
|  | Linked to Scale | Link the speed of the particle with its size. The larger it is, the faster it will appear to have depth. It doesn't seem to be very strictly proportional. | ―
|  | Speed Angle | The direction of the initial velocity of the particles. 0 is down, 90 is right. | ○
|  | Use Gradient Angle | When ON, the initial velocity is adjusted to the gradient vector of the Control image used for Speed Angle. |
| Size,Mass& Orientation | Size | Specify the maximum / minimum size range. If there is a Control image, the higher the brightness, the larger the image placed at the particle. Random if there is no Control image. | ○
|  | Perspective Distribution | When ON and there is a Size Control image, the density of the particles is arranged in inverse proportion to their sizes. Used to place deep particles, such as in sea waves. When this option is ON, the Control Image Gradation option will be ignored. |
|  | Use Control Image for the Whole Lifetime | When ON, the size will be driven according to the brightness of the Control image, at the position of the particle, for each frame. When OFF, the Control image is used only when particles are generated. After that, they will maintain the same size until they disappear. | ―
|  | Mass | Specify the maximum / minimum range of mass for each particle. Mass is a factor related to the speed, given by the Gravity below. | ―
|  | Orientation | Specifies the maximum / minimum range of the initial orientation angle of the particles. 0 means no rotation, 90 means 90 degrees to the right. | ○
| Trail | Trail | Display a trail for each particle, that fades out over the number of frames specified in the Trail parameter. | ―
|  | Step | The particle trail will be displayed every Step value. That is, there will be (Trail/Step) images displayed in the trail. | ―
| Lifetime | Lifetime | Specify the maximum / minimum range of a particle life (in frames). Lifetime is the length of frames since particles are born, until they completely disappear. | ○
|  | Use Column Duration for Lifetime | When ON, the particles lifetime will be equal to the length of the Source Column. | ―
| Top Layer | Top Layer | Specify the stacking order of the particles. | ―
Page | Category | Param Name | Description | Control Image
Environment | Gravity | Gravity | Specify the value of gravity (= acceleration) to be given to particles. Negative values reverse the direction. When a Control image is connected, the value of Gravity Angle below is not used, and the gradient of luminance of the Control image becomes the gravity. Brighter pixels will produce more gravity. | ○
|  | Gravity Angle | Specifies the direction of gravity. 0 for downwards. At 90 it goes to the left. | ―
| Friction | Friction | Specifies the value of the friction force that stops the movement of particles. The maximum frictional force is obtained when the luminance of the Control image is maximum. Ignored if there is no Control image connected. | ○
| Wind | Wind Intensity | Specifies the speed of the wind that affects particles in an uniform fashion. It is added to their speed, not acceleration. Its effect is somewhat similar to the initial speed (Birth Param → Speed). | ―
|  | Wind Angle | Specify the direction of the wind. 0 is upwards, 90 is to the right. | ―
| Scattering | Horizontal | Specifies a range of horizontal speed values that give random motion to the particles. | ○
|  | Vertical | Specifies a range of vertical speed values that give random motion to the particles. | ○
|  | Swing Mode | Random: Change the Horizontal / Vertical values for each frame. However, the sign of the horizontal / vertical values does not change during the number of frames specified by the lower Swing value. Smooth: Horizontal / Vertical values will remain unchanged for the number of frames specified by the lower Swing value. | ―
|  | Swing | When Swing Mode is Smooth, specify the minimum / maximum values of the frame interval for resetting the Horizontal / Vertical values. | ―
Page | Category | Param Name | Description | Control Image
Animation | Rotation | Rotation Speed | Specify the rotation speed of each particle. Rotation angle per frame (in degrees). | ―
|  | Extra Speed | Specifies the range of angles that are randomly added to each particle. | ―
|  | Swing Mode | Random: Recalculate the Extra Speed for each frame. Smooth: Rotates at the same Extra Speed value for the number of frames specified by Rotation Swing below. | ―
|  | Rotation Swing | When Swing Mode is Smooth, specify the minimum / maximum value of the frame interval for re-setting the ExtraSpeed value. | ―
|  | Follow Particles Movement | When ON, the rotation angle of the particles is set along the traveling direction. The rotation angle is 0 when moving to the right horizontal direction. | ―

Opacity

Opacity

Minimum / maximum opacity of particles. Fade in from the minimum value to the maximum value and fade out to the minimum value.
When a Control image is connected, the opacity of the particle at each frame time is determined according to the luminance value of the Control image. Minimum opacity is reached when black. Opacity is updated every frame.
Opacity, when driven by a Control image can be overlaid with the Fade-in / out parameters below.

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|  | Fade-in Frames | Number of frames for the Fade-in. | ―
|  | Fade-out Frames | Number of frames for the Fade-out. | ―
|  | Trail Opacity | When a trail is defined in Birth Params → Trail, it specifies the minimum / maximum values for the opacity of the particles in the trail. | ―
| Size Increase | Size Intensity | Specify the minimum / maximum values of the size increase / decrease (as a percentage) that changes randomly in each frame. | ○
Page | Category | Param Name | Description | Control Image
Colors | Birth Color | Birth Color | Defines the color at the moment particles are generated. When each particle is generated, it is randomly selected from the color range specified in the spectrum. If a Control image is connected, the (premultiplyed) RGB values of the image will be used for chosing each particle color. | ○
|  | Birth Spread | Birth color Spread for the particles. | ―
|  | Birth Intensity | Birth Color influence (%) | ―
|  | Pick Control Image's Color for Every Frame | Allows to change the color of the particles, at every frame, by using the Control image pixels at the current particle position. | ―
| Fade-in Color | Fade-in Color | Determines the color that the particles fade in. Randomly chosen from the color range specified in the spectrum. If a Control image is connected, the (premultiplyed) RGB values of the image will be used for the particle color. | ○
|  | Fade-in Spread | Spread for the fade-in of the particles. | ―
|  | Frame Range | Number of frames, counted from particle generation time, to Fade-in color. | ―
|  | Fade-in Intensity | Fade-in Color influence (%). | ―
| Fade-out Color | Fade-out Color | Determines the color that the particles fade out to. Randomly chosen from the color range specified in the spectrum. If a Control image is connected, the (premultiplyed) RGB values of the image will be used for each particle color. | ○
|  | Fade-out Spread | Spread for the fade-out of the particles. | ―
|  | Frame Range | Number of frames to Fade-out color, counted from the time of death of the particle backwards. | ―
|  | Fade-out Intensity | Fade-out Color influence (%). | ―