Particles

This visual element is responsible for rendering particles in the viewports. Typically, particles are visualized as simple spheres, but you can switch to other, more complex geometric shapes if desired.

The Particles visual element provides a set of parameters controlling the visual representation of all particles, which will be described in the section below. Additionally, the visualization is affected by certain properties, listed in the following table, that particles may optionally possess. By setting the values of these particle properties, for example using the Compute property modifier, you can control the visualization on a per-particle basis.

Particle propertyData type / ComponentsDescription
ColorReal (R, G, B)

Controls the display color of individual particles. Red, green and blue components are in the range [0,1].

RadiusReal

Controls the display size of individual particles.

Particle TypeInteger

Used to determine size and color if the Radius or Color properties are not present.

TransparencyReal

Controls the transparency of individual particles. Must be in the range [0,1].

Aspherical ShapeReal (X, Y, Z)

Controls the size of particles with a non-symmetric shape. The exact interpretation of this property depends on the selected Shape setting, see section below.

OrientationReal (X, Y, Z, W)

Specifies the orientation of particles with non-symmetric shapes. The rotation of each particle is specified in terms of a quaternion. See this page for more information.

Parameters

Shape

Selects the display shape of particles. The current program version offers the choice between the following modes:

Sphere/Ellipsoid
Particles are visualized as 3d spheres. Unless the Aspherical Shape particle property has been defined; then they are rendered as ellipsoidal particles. In this case, the three components of the Aspherical Shape vector property control the half lengths of the principal axes of each ellipsoid and the scalar Radius property is ignored.
Circle
Particles are visualized as flat-shaded circles facing the viewer. Note that some rendering engines do not support this mode.
Cube/Box
Particles are visualized as cubes if the Aspherical Shape particle property is not present. The Radius property can be used to control the edge half-length of the cubes in this case. If the Aspherical Shape particle property is present, particles are rendered as non-cubic boxes with the given half-lengths along the three edges.
Square
Particles are visualized as flat-shaded squares facing the viewer. Note that some rendering engines do not support this mode.
Cylinder
Particles are visualized as cylinders. The X-component of the Aspherical Shape vector property controls the cylinder radius of particles in this mode, and the Z-component controls the length of the cylindrical particles. By default, cylinders are aligned along the z-axis. If present, the Orientation particle property rotates the cylinders.
Spherocylinder
Particles are visualized as cylinders with round caps at each end (capsules). The behavior is the same as for mode Cylinder.

Default particle radius

Specifies the display size of particles that have an otherwise unspecified size. This size value is only used for particles for which none of the following applies:

  • The Radius particle property has a non-zero value.

  • The particle's type, as specified by the Particle Type, has a non-zero radius.

In other words, this parameter provides a fallback value if no display size has been set on a per-particle basis or on a per-type basis.

Rendering quality

This parameter controls the method used for rendering the particles in the interactive viewports. The following modes are available and affect only the rendering of spherical particles:

Low

Particles are rendered as texture-mapped imposters facing the viewer. Particles do not have depth in this mode, and intersections between spherical particles may not be displayed correctly. This mode is the fastest.

Medium

Particles are rendered as texture-mapped imposters facing the viewer. An OpenGL fragment shader is used to compute depth information for each rendered pixel to produce reasonable looking sphere-sphere intersections for overlapping particles.

High

Particles are rendered as true spheres using an OpenGL fragment shader, which computes the ray-sphere intersection for every rendered pixel.

Automatic

OVITO automatically switches between the three quality levels above depending on the number of particles to render in the interactive viewports. For less than 4,000 particles, the high-quality method is used. For more than 400,000 particles, the lowest quality mode is used. Irrespective of the particle number, high-quality mode is always used to produce a final output image.

See also

ParticlesVis (Python API)