Visualization

These settings only affect drawing in the 3d viewport.

• Vel: draw lines to show particle velocity.
• Size: draw a circle around particles to show their size;
• Num: next to each particle, draw their number.
• Draw Size: draw size of particles in pixels.
• Disp: percentage of particles to display.

• Material: the material number to use for rendering the particles.
• Col: use the material color for drawing the particles in the 3d viewport.
• Emitter: enable or disable rendering of the emitter mesh.
• Parents: with child particles enabled, draw the parents too.
• Unborn: show particles before they are emitted.
• Died: shows particles after they have died.

This visualization mode is useful if you don't want to show the particles, but just want to use them to affect other things, like acting as effectors for other particles, targets for a keyed system or to explode the emitter.

With these visualization type particles are rendered as halos. They are displayed in the 3d viewport as a point, circle, cross and axis respectively. These modes of visualization don't have any special option, but can be very useful when you have multiple particle systems at play, if you don't want to confuse particles of one system from another (especially in simulations using Boids physics).

Render the particles as lines.

• Speed: multiply line length by particle speed.
• Back: length of the line's tail.
• Forward: length of the line's head.
   

This is the default visualization for hair, rendering as lines in the 3d viewport and as a strand in the final render. Control over the width of the strands is available the in the material strand settings. Cached or Keyed particles are needed and a warning will be issued by Blender if it is not the case.

• Steps: number of subdivision steps for the curve in the 3d viewport.
• Render: number of subdivision steps for the curve for rendering.
• Abs Length: limit length of child particles.
  • Max Length: maximum length in blender units.
• RLength: randomize length.
• B-Spline: use b-spline interpolation rather than cardinal interpolation. The former is smoother, but does not go through the key points.
• Strand Render: use a special strand primitive for faster hair render (more info).
  • Angle: threshold for splitting the curve into smaller segments.
• Adaptive Render: an alternative to the Strand Render option, to adaptively subdivide the curve.
  
  • Angle: threshold for splitting the curve into smaller segments.
  • Pixel: number of pixel to cover before making another segment.

These visualization modes allow you to use a duplicate an object or objects in place of particles. This option is very interesting both for ecosystems simulations or for flocks of specific objects. For control over the rotation of the object the physics rotation settings can be used. Note that for Hair the rotation is derived differently, using the direction of the hair, which allows for example to create feathers and edit them.

In the Object visualization mode, the specified object (OB: field) is duplicated in place of each particle.

In the Group visualization mode, the objects that belong to the group(GR: field) are duplicated sequentially in the place of the particles.

• Pick Random: The objects in the group are selected in a random order, and only one object is displayed in place of a particle
• DupliGroup: Use the whole group at once, instead of one of its elements, the group being displayed in place of each particle

Please note that this mechanism fully replaces old Blender particles system using parentage and DupliVerts to replace particles with actual geometry. This method is fully deprecated and doesn't work anymore.

Billboards are aligned square planes. How they are aligned, and what are they aligned to can be influenced in many ways. Texturing billboards is done by using uv coordinates that are generated automatically for them.

The main thing to understand is that if the object doesn't have any UV Layers, you need to create at least one in the object Edit buttons for any of these to work. Moreover, material should be set to UV coordinates in the Map Input panel.

• Lock: Lock the align axis
• Align to: Dropdowmenu indicating the axis that billboards are prealigned to before turning them to the target. It could be X, Y, Z or Velocity. If View is used, then no prealignment takes place.
• Tilt: Rotation angle of the billboards planes.
• Rand: Random variation for the rotation angle.
• UV Split: The amount of rows/columns in the texture to be used.
• Animate: Dropdown menu, indicating how the split UVs could be animated (changing from particle to particle with time):
  • None: No animation occurs.
  • Time: The sections of the texture are gone through sequentially in particles' lifetimes.
  • Angle: Change the section based on the angle of rotation around the "align to" axis, if view is used the change is based on the amount of tilt.
• Offset: Specifies how to choose the first part (of all the parts in the n*n grid in the texture defined by the "uv split" number) for all particles.
  • None: All particles start from the first part.
  • Linear: First particle will start from the first part and the last particle will start from the last part, the particles in between will get a part assigned linearly from the first to the last part.
  • Random: Give a random starting part for every particle.
• OffsetX: Offset the billboard horizontally in relation to the particle center.
• OffsetY: Offset the billboard vertically in relation to the particle center.
• OB: The target object that the billboards are facing. By default the active camera is used.
• UV Channel: Billboards are just square polygons. To texture them in different ways we have to have a way to set what textures we want for the billboards and how we want them to be mapped to the squares. The only useful way currently is to create "fake uv channels" for the emitter. These can then be set in the texture mapping buttons to set wanted textures for different coordinates.
  • Normal: Coordinates are the same for every billboard, and just place the image straight on the square. These are very usefull to create billboards with soft boundaries like halos for example with a sphere/halo blend texture.
  • Time-Index (X-Y): Coordinates actually define single points in the texture plane with the x-axis as time and y-axis as the particle index. For example using a horizontal blend texture mapped to color from white to black will give us particles that start off as white and gradually change to black during their lifetime. On the other hand a vertical blend texture mapped to color from white to black will make the first particle to be white and the last particle to be black with the particles in between a shade of gray.
  • Split: Coordinates are a single part of the "uv split" grid, which is a n*n grid over the whole texture. What the part is used for each particle and at what time is determined by the "offset" and "animate" controls. These can be used to make each billboard unique or to use an "animated" texture for them by having each frame of the animation in a grid in a big image.
• UV: Set the name of the UV layer to use with billboards, default is active UV layer (check Mesh panel in the Editing [F9] menu)