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Point Clouds


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Point cloud are procedurally created groups of particles that can be assigned as Point Sources in the same way any Particle Simulation can be. They are differentiated from Particle Simulations in that any animation assigned or applied is either pre-generated as is the case with the RealFlow particle importer, or kinematic in nature (meaning is is assigned with keyframes, not through an evaluated simulation). The 'Particle Generator' allows users to easily create ordered arrays of particles, while the 'Point Cloud' generates a volume of random particles. The 'Surface Particle Generator' is used to create randomly placed particles over a geometric surface. Once created users can assign these items as Point Sources for 'Replicators', 'Blobs', 'Sprites' or 'Volumes'. Select from any of the Point Clouds items below to view the appropriate documentation-

 

Surface Particle Generator

Particle Cloud

The 'Surface Particle Generator' produces similar results to the Shader Tree 'Surface Generator', in that it is used to scatter vertices (particles) across a specific item or surface. However, the Particle Generator is evaluated at the scene level making it more flexible and faster. The resulting particles can then be used as a point source for Blobs, Sprites, Volumes, Replicators and when working with Texture Replicators. One thing to keep in mind though, that since it is scene evaluated, it wont take in to consideration rendering effects such as Displacements applied to the surface; in that case users should apply the Surface Generator.

Adding a Particle Generator

Users can add a Surface Particle Generator item simply by using the 'Add Item' function of the Items List. LMB+click on the button to open the menu, then select the "Particles > Surface Particle Generator" option. Once added, users can then specify the target geometry using the 'Source Surface' option. The 'Material Tag' option further limits the particles to specific areas of a Mesh item.

Particle GeneratorName: This data field displays the current items name. Users may easily change it by LMB-clicking within the field and typing the new name.

Transform--

Position: An Item transform that allows the user to numerically position the item in XYZ space.

Rotation: An Item transform that allows the user to numerically set the rotation of the item. Rotation transforms originate from the Position value.

Order: Allows the user to set the order that rotations are applied to the item. Changing the order that rotations are applied can sometimes help to reduce or eliminate gimbal lock.

Scale: An Item transform that allows the user to numerically set the size of the item. Scale transforms originate from the Position value.

Reset: Resets the selected transform values to (0,0,0) returning the items back to their default state.

Zero: Resets the chosen transform property values to '0', leaving the 'Center' position and Mesh position intact. This is done by adding a negative transform item to the Mesh items channels.

Add: Transform Items are the channel groups associated to an item that store its transform values, controlling its position, rotation and/or scale. By default, new items do not have any transform items associated with them (even though they are visible here within the Properties panel). This is useful as an optimization as only the necessary transforms are added on an as-needed basis, reducing scene overhead. There are several ways to add them. One is by simply transforming the target item with one of the various transform tools (or by editing the values input fields). This action will cause the particular transform item to be added automatically to the 'Channels' viewport list. The 'Add' function here can also be used to add the selected set of transforms to the Channel list while keeping the default 0,0,0 values (a necessary step for 'Referencing', in order to override the channels, they must first exist).

Generator--

Source Surface: This dropdown menu can be used to specify an item within the scene to apply the particles over its surface. This is the equivalent of an 'Item' mask in the Shader Tree.

Material Tag: The 'Material Tag' option allows users to further limit the application of the Particles by specifying a surface definition from the dropdown menu. This is the equivalent of an 'Material' mask in the Shader Tree.

Average Spacing: Precisely as the name implies, the 'Average Spacing' value specifies the average distance between particles.

Minimum Spacing: Where the 'Average Spacing value only specifies an average, the 'Minimum Spacing' value allows one to specify the minimum amount of space between replicated items, especially useful in eliminating overlaps for neighboring replicas when used as a Replicator source.

Density Multiplier: The 'Density Multiplier' offers simplified control over the overall density of replicated items. Lower values will reduce the overall number of replicas while higher values will increase the overall number of replicas up to the 'Particle Ceiling' value.

Seed: The 'Seed' value is an initial setting used when random numbers are generated. Different 'Seed' values will produce different random variations, in this case, initial particle positions. However you will want to use the same 'Seed' value when it is necessary that items retain the same variations.

Scale Factor: The 'Scale Factor' acts to control the scale of replicated objects, eliminating the need to manually scale the base 'Prototype' item. With a value of 100%, replicated items would be generated at the identical size of the prototype, smaller values would decrease each replicas size, while larger value would increase each replicas size.

Particle Ceiling: The 'Particle Ceiling' is a maximum for the total number of generated particles.

Distribution--

Density Vmap: Users can create an embedded Weight Map on the target surface and use its values to control the Density of the particle distribution, eliminating the need to create custom image maps to do so. Any available Weight Maps can be selected from this drop-down assigning it to control the density as a multiplier over the regular density. A Weight Value of 1 (100%) would be the normal density, attenuating toward a Weight Value or 0 at 0% density. Weight values can also go above 1 for added density control.

Density Gradient Input: Users can define an 'Input' criteria that will then be used to additionally control the density of the resulting particles. With the input defined, the actual 'Density Gradient' defines the density amount.

Density Gradient: Using a mini-gradient input, the density can be modified with gradient keys that represent a percentage of the original density. Much like how a keyframe defines a value in time, these keys represent a value across the selected input parameter (such as over the angle of 'Slope'). Keys can be added by MMB+clicking along the length of the gradient input and then LMB+click and drag the key icon up or down adjusting the value. The grayscale bar directly below gives visual feedback as to how the values fade from one key to the next; white will produce 100% density attenuating toward black at 0% density. Opening the Gradient editor will allow users to go above 100%.

Size Vmap: Users can create an embedded Weight Map on the target surface and use its values to control the scale of the elements connected to the generated particles, eliminating the need to create custom image maps to do so. Any available Weight Maps can be selected from this drop-down assigning it to control scale the as a multiplier over the regular sizing. A Weight Value of 1 (100%) would be the normal scale, attenuating toward a Weight Value or 0 at 0% scale. Weight values can also go above 1 for greater than 100% scale control.

Size Gradient Input: Users can define an 'Input' criteria that will then be used to additionally control the scale of the elements connected to the generated particles. With the input defined, the actual 'Size Gradient' defines the scaling amount.

Size Gradient: Using a mini-gradient input, the scale can be modified with gradient keys that represent a percentage of the original scale. Much like how a keyframe defines a value in time, these keys represent a value across the selected input parameter (such as over the angle of 'Slope'). Keys can be added by MMB+clicking along the length of the gradient input and then LMB+click and drag the key icon up or down adjusting the value. The grayscale bar directly below gives visual feedback as to how the values fade from one key to the next; white will produce 100% scale attenuating toward black at 0% scale.

Vector Vmap: Users can create an embedded Vertex Vector Map on the target surface and use its values to control the orientation and scale of the elements connected to the generated particles, eliminating the need to create custom image maps to do so. This allows users to use the sculpting tools, like with Hair Guides, to intuitively control the replicated elements. Note that elements controlled by Vector Vertex Maps will automatically adapt to surface deformations as the Vector Maps are defined in tangent space.

 

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