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pEmitter [pEm]

The pEmitter tool is the main source of particles (pImageEmitter is another) and will usually be the first tool used in any new particle system. This tool contains controls for setting the initial position, orientation and motion of the particles, as well as controls for the visual style of each particle. Like all other Particle tools (with the exception of the pRender tool), the pEmitter produces a particle set, not a visible image, and therefore cannot be viewed directly on a display. To view the output of a particle system, add a pRender tool after the pEmitter.

Controls Tab

This tab contains settings that affect the physics of the particles emitted by the tool. These settings do not directly affect the appearance of the particles. They modify behavior like velocity, spin, quantity and lifespan instead.

The Random Seed slider is used to seed all of the variance and random number generators used by the tool when creating the particle system. Two pEmitter tools with exactly the same settings for all controls and the same random seed will generate exactly the same particle system. Changing the random seed will cause variation between the tools. Click on the Randomize button to automatically set a randomly-chosen value for the Random Seed.

This control is used to set the amount of new particles generated on each frame. A value of 1 would cause one new particle to be generated each frame. By frame 10, there would be a total of 10 particles in existence (unless Particle Lifespan was set to less than 10).

Animate this parameter to specify the number of particles generated in total. For example, if only 25 particles in total are desired, animate the control to produce five particles on frame 0-4, then set a key on frame five to generate zero particles for the remainder of the project.

This modifies the amount of particles generated for each frame, as specified by the Number control. For example, if Number is set to 10.0 and Number Variance is set to 2.0, the emitter will produce anywhere from 9-11 particles per frame. If the value of Number Variance is more than twice as large as the value of Number, it is possible that no particles will be generated for a given frame.

This control determines how long a particle will exist before it disappears or `dies'. The default value of this control is 100 frames, although this can be set to any value. The timing of many other particle controls is relative to the Lifespan of the particle. For example, the size of a particle can be set to increase over the last 80% of its life, using the Size Over Life graph in the Style tab of the pEmitter.

Like Number Variance, the Lifespan Variance control allows the Lifespan of particles produced to be modified. If Particle Lifespan were set to 100 frames and the Lifespan Variance to 20 frames, particles generated by the emitter would have a lifespan of 90-110 frames.

This provides the ability to specify from where the color of each particle is derived. The default setting is Use Style Color, which will provide the color from each particle according to the settings in the Style tab of the pEmitter tool.

The alternate setting is Use Color From Region, which overrides the color settings from the Style tab and uses the color of the underlying bitmap region.

The 'Use Color From Region' option only makes sense when the pEmitter region is set to use a bitmap produced by another tool in the composition. Particles generated in a region other than a bitmap region will be rendered as white when the 'Use Color From Region' option is selected.

This control determines whether or not particles can be `born' outside of the boundaries of the pEmitter region. By default, the value is set to zero, which will restrict the creation area for new particles to the exact boundaries of the defined region. Increasing this control's value above 0.0 will allow the particle to be born slightly outside of the boundaries of that region. The higher the value, the `softer' the region's edge will become.

These determine the initial speed or velocity of new particles. By default, the particle has no velocity and will not move from its point of origin unless acted upon by outside forces. A velocity setting of 10.0 would cause the particle to cross the entire width of the image in one step so a velocity of 1.0 would cause the particle to cross the width of the image over 10 frames.

Velocity Variance modifies the velocity of each particle at birth, in the same manner described in Lifespan Variance and Number Variance above.

This determines the angle at which particles with velocity applied will be heading at its birth.

This is as above, except this control determines the angle of the particles along the Z space axis (toward or away from the camera).

This menu control provides two options to help determine the orientation of the particles emitted. When the particles are spherical, the effect of this control will be unnoticeable.

Absolute Rotation

The particles will be oriented as specified by the Rotation controls, regardless of velocity and heading.

Rotation Relative To Motion

The particles will be oriented in the same direction as the particle is moving. The Rotation controls can now be used to rotate the particle's orientation away from its heading.

These controls allow for Rotation of the individual particles. This can be particularly useful when dealing with a bitmap particle type, as the incoming bitmap may not be oriented in the desired direction.

Rotation XYZ Variance can be used to randomly vary the rotation by a specified amount around the center of the Rotation XYZ value to avoid having every particle oriented in the exact same direction.

These provide a spin to be applied to each particle at birth. The particles will rotate 'x' degrees each frame, as determined by the value of Spin XYZ.

The Spin XYZ variances will vary the amount of rotation applied to each frame in the manner described by Number Variance and Lifespan Variance documented above.

Sets Tab

This tab of controls consists of 32 checkboxes that can be used to assign the particles generated by this pEmitter to a specific set.

These controls are useful when a pMerge tool is used to combine multiple pEmitter streams into one. Assigning sets allows individual groups of particles to be addressed by modifier tools like pDirectionalForce and pTurbulence. Sets can also be used to differentiate the particles created with a pSpawn or a pChangeStyle tool from their source particles.

To assign the particles created by a pEmitter to a given set, simply select the checkbox of the set number you want to assign. A single particle stream can be assigned to one or multiple sets.

Style Tab

The Style tab provides controls that affect the appearance of the particles, allowing the look and feel of the particles to be determined and animated over time.

The Style Menu control provides access to the various types of particles supported by the Particle Suite. Each style has its own specific controls, as well as controls it will share with other styles.

Point Style

This option produces particles exactly one pixel in size. Controls that are specific to Point Style are Apply Mode and Sub Pixel Rendered.

Bitmap Style and Brush Style

Both the Bitmap and Brush Styles produce particles based on an image file. The Bitmap Style relies on the image from another tool in the Flow and the Brush Style uses image files in the brushes directory. They both have numerous controls for affecting their appearance and animation, described below.

Blob Style

This option produces large, soft spherical particles, with controls for Color, Size, Fade timing, Merge method and Noise.

Coopers Style

This style produces particles composed of bottle caps from the Coopers brand of beer (the best beer in Australia, and quite possibly the world. To dispute our choice please send samples of the superior brew to eyeon Software, c\o the Product Manager).

Line Style

This style produces straight line-type particles with optional 'falloff'. The Size To Velocity control described below (under Size Controls) is often useful with this Line type. The Fade control adjusts the amount of falloff over the length of the line.

Point Cluster Style

This style produces small clusters of single pixel particles. Point Clusters are similar to the Point style, however they are more efficient when a large quantity of particles is required. This style shares controls with the Point style. Additional controls specific to Point Cluster style are Number of Points and Number Variance.

This standard Color Control selects the color and alpha values of the particles generated by the emitter.

These range controls provide a means of expanding the colors produced by the pEmitter. Setting the Red variance range at -0.2 to +0.2 will produce colors that vary 20% on either side of the red channel, for a total variance of 40%. If the pEmitter is set to produce R0.5, G0.5, B0.5 (pure grey), the variance shown above will produce points with a color range between R0.3, G0.5, B0.5 and R0.7, G0.5, B0.5.

To visualize color space as values between 0-256 or as 0-65535, change the values used by Fusion using the Show Color As option provided in the General tab within the Preferences dialog.

This checkbox locks the color variance of the particles. Unlocking this allows the color variance to be applied differently to each color channel, giving rise to a wider range of colors.

This standard gradient control allows for the selection of a range of color values to which the particle will adhere over its lifetime.

The left point of the gradient represents the particle color at birth. The right point shows the color of the particle at the end of its lifespan.

Additional points can be added to the gradient control to cause the particle color to shift throughout its life.

This type of control can be extremely useful for fire-type effects (for example, the flame may start out blue, turn orange and end a darker red). The gradient itself can be animated over time by right-clicking on the control and selecting Animate from the context menu. All points on the gradient will be controlled by a single Color Over Life spline, which controls the speed at which the gradient itself changes. You may also use the From Image modifier, which produces a gradient from the range of colors in an image along a line between two points.

The majority of the Size Controls are self-explanatory. The Size and Size Variance controls are used to determine the size and degree of size variation for each particle. It is worth noting that the Point style does not have size controls (each point is a single pixel in size and there is no additional control).

When a Bitmap Particle style is used, a value of 1.0 indicates that each particle should be exactly the same size as the input bitmap. A value of 2.0 will scale the particle up in size by 200%. For the best quality particles, always try to make the input bitmap as big, or bigger, than the largest particle produced by the system.

For the Point Cluster style, the size control adjusts the density of the cluster, or how close together each particle will get.

There are additional size controls that can be used to further adjust the size of particles based on velocity and depth.

This increases the size of each particle relative to the Velocity or speed of the particle. The velocity of the particle is added to the size, scaled by the value of this control.

1.0 on this control, such as for a particle travelling at 0.1, will add another 0.1 to the size (velocity * sizetovelocity + size = newsize). This is most useful for Line styles, but the control can be used to adjust the size of any style.

This control measures the degree to which the size of each particle is increased or decreased according to its depth (position in Z space). The effect is to exaggerate or reduce the impact of perspective. The default value is 1.0, which provides a relatively realistic perspective effect.

Objects on the focal plane (Z = 0.0) will be actual-sized. Objects farther along Z will become smaller. Objects closer along Z will get larger.

A value of 2.0 will exaggerate the effect dramatically, whereas a value of 0.0 will cancel the effects of perspective entirely.

This LUT spline control determines the size of a particle throughout its lifespan. The vertical scale represents a percentage of the value defined by the Size control, from 0 to 200%. The horizontal scale represents a percentage of the particle's lifespan (0 to 100%).

This graph supports all of the features available to a standard LUT editor. These features can be accessed by right-clicking on the graph. It is also possible to view and edit the graph spline in the larger Spline view.

This simple range slider provides a mechanism for fading a particle at the start and end of its lifetime. Increasing the Fade In value will cause the particle to fade in at the start of its life. Decreasing the Fade Out value will cause the particle to fade out at the end of its life.

This control's values represent a percentage of the particle's overall life, therefore, setting the Fade In to 0.1 would cause the particle to fade in over the first 10% of its total lifespan. For example, a particle with a life of 100 frames would fade in from frame 0..10.

This set of particle controls affects the way individual particles are merged together. The Subtractive/Additive slider works exactly as documented in the standard Merge tool. The Burn-In control will cause the particles to overexpose, or `blow out', when they are combined together.

None of the Merge controls will have any effect on a 3D particle system.

This set of particle controls can be used to apply a Blur to the individual particles. Blurring can be applied globally, by age, or by Z depth position.

None of the Blur controls will have any effect on a 3D particle system.

These controls apply Blur to each particle. Unlike the Blur in the pRender tool, this is applied to each particle independently before the particles are merged together. The Blur Variance slider modifies the amount of blur applied to each particle.

This spline graph controls the amount of Blur that is applied to the particle over its life. The vertical scale represents a percentage of the value defined by the Blur control. The horizontal scale represents a percentage of the particle's lifespan.

This graph supports all of the features available to a standard LUT editor. These features can be accessed by right-clicking on the graph. It is also possible to view and edit the graph spline in the larger Spline view.

This slider control applies blur to each particle based on its position along the Z axis.

The DoF Focus range control is used to determine what area of the image remains in focus. Lower values along Z are closer to the camera. Higher values are farther away. Particles within the range will remain in focus. Particles outside that range will have the blur defined by the Z Blur control applied to them.

This control only applies to 2D particles. 3D particle systems are not affected.

Add

Overlapping particles are combined by adding the color values of each particle together.

Merge

Overlapping particles are merged together.

(Bitmap Style Only) This control appears when the Bitmap style is selected, along with an orange Style Bitmap input on the tool's icon in the Flow view. Connect a 2D tool to this input to provide images to be used for the particles. You can do this on the Flow view, or you may drag and drop the image source tool onto the Style Bitmap control from the Flow or Timeline, or right-click on the control and select the desired source from the Connect To menu.

(Brush Style Only)This drop-down list shows the names of any image files stored in the Brushes: directory. The location of the Brushes: directory is defined in the Preferences dialog, under Path Maps. The default is the Brushes subdirectory within Fusion's install folder. If no images are in this directory, the only option in the menu will be None, and no particles will be rendered.

(Bitmap Style Only) This list determines how the animation of the bitmap source is applied to newly-created particles. It can be hard to visualize the impact of this control until it has been experimented with. A good way to experiment is to load the flow in the Fusion>Examples directory called pTextParticleAge.comp and try out the three settings. View the Text tool in the display view and the pRender tool another view, then step through the frames using the [ and ] keys.

Over Time

All particles use the image produced by the Style Bitmap tool at the current time, and change to each successive image together in step, as time increases. A particle created at frame 1 will contain the image at frame 1 of the Style Bitmap. At frame 2, the original particle will use the image from frame 2, and so will any new particles. All created particles will share exactly the same bitmap image from their source at all times.

Particle Age

Each particle animates through the sequence of images provided by the Style Bitmap tool, independently of other particles. In other words, an individual particle's appearance is taken from the Style Bitmap tool at successive times, indexed by its age.

Particle Birth Time

New particles take the image from the Style Bitmap tool at the current time and keep it unchanged until the end of the particle's lifespan. Thus, particles generated on a given frame will all have the same appearance, and will stay that way.

(Bitmap Style Only) This control allows the bitmap source frame to be Offset in time from the current frame.

(Bitmap Style Only) This control can be used to scale the time range of the source bitmap images by a specified amount. For example, a scale of 2 will cause the particle created at frame 1 to be read from the bitmap source at frame 2.

(Bitmap and Brush Style Only) This control is used to apply a correction to the overall Gain of the image that is used as the bitmap. Higher values produce a brighter image, whereas lower values reduce both the brightness and the transparency of the image.

(Blob Style Only) Increasing this control's value will introduce grain-type noise to the blobby particle.

(Line Style Only) The Fade control adjusts the falloff over the line particle's length. The default value of 1.0 causes the line to fade out completely by the end of the length.

(Point and Point Cluster Style Only) This checkbox determines if the point particles are rendered with Sub Pixel precision, which provides smoother looking motion but blurrier particles that take slightly longer to render.

(Point Cluster Style Only) The value of this control determines how many points are in each Point Cluster.

Region Tab

The controls found under the Region tab are used to determine what portion of the image will actually generate particles. This has no affect on where a particle can go, only on where it is actually created or born. Only one region can be applied to any given particle emitter.

2D-type regions will produce particles along a flat plane in Z Space, usually positioned at Z = 0.0. 3D emitters possess depth and can produce particles inside a user-defined, three-dimensional region.

There are seven types of regions available, each with its own set of controls as described in the Common Particle Controls.

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Tips for pEmitter (edit)

EyeonTips:Manual/Tool Reference/Particles/pEmitter