This extension defines how dust generated by the earthmoving operations behave, and is used to configure dust emission and appearance.

The Earthwork Systems module models the generation of dust when tools dig through or drop soil. The events which lead to dust generation are:

• Tools digging through soil in a soil grid (Earthwork Zone or soil bin).
• Tools compressing soil in a soil grid.
• Soil particles being dropped onto a soil grid.

To add a Soil Dust extension:

1. In your scene or mechanism, select Earthwork Systems in the Toolbox.
2. Double-click Soil Dust to add one, or drag it into the 3D View.

Configuring the Dynamic Properties for Soil Dust

The amount of dust generated due to these events, and its visual appearance, can be configured by clicking the Soil Dust > Dynamics in the Explorer panel. The Properties panel now displays the Dynamics properties for the soil dust.

• Dust Emission Probability: Sets how likely dust is to be generated by the occurrence of the events outlined in the introduction above.
• Minimum Impact Strength: This the minimum strength required in an impact to trigger the emission of a dust cloud. No dust is generated if the impact strength is below the value specified here.
  The unit of the impact strength is defined as the time rate of change of the applied force during the impact.
  The amount of dust which is generated as the result of an impact event (soil particles dropped, or tool compressing soil grid) is scaled based on the impact strength.
• Maximum Impact Strength: The maximal effect (most dust generated) is achieved when the impact strength reaches the value specified by this field.
• Minimum Impact Velocity: This sets the minimum impact velocity necessary to trigger the emission of a dust cloud (in meters per second).
• Dust Emission List: This output is set automatically and is used to drive the Graphics extension.

Configuring the Graphic Properties for Soil Dust

This extension defines the visual appearance of the generated dust, and is accessed by Soil Dust > Graphics in the Explorer panel. The Properties panel now displays the Graphics properties for the soil dust.

• Local Transform: Not used.
• Parent Transform: Not used.
• Visible: If selected, the dust clouds appear in the 3D viewport.
• Cast Shadow: If selected, the dust clouds will cast shadows (this is computationally intensive).
• Receive Shadow: If selected, the dust clouds will receive shadows cast by other objects.
• Graphics Material: Points to a graphics material within a Gallery, that determine the general appearance of the soil dust (texture, reflectivity, etc.).
• Particle Lifetime (in seconds): Determines how long the dust particle will exist after its creation.
• Particle Size Change: Determines the range of possible sizes of the dust particles, in meters. The Z-component is ignored.
• Particle Alpha Change: Determines the range of possible transparency of the dust particles. The Z-component is ignored.
• Particle Alpha Fade Interval: Determines how many seconds will pass between the particles fading in and out.
• Particle Color Start: Determines the starting color of the particles. The four color fields represent red, green, blue and transparency.
• Particle Color End: Determines the ending color of the particles. The four color fields represent red, green, blue and transparency.
• Particle Color Change: Sets a variance in color for the particles within the start and end colors selected above.
• Particle Angle Start Range: Determines the range of angles at which the particles can be oriented at their creation. The Z-component is ignored.
• Emission Rate: Determines how many particles are emitted when an impact event is received (in hertz).
• Spray Cone Theta Range: Determines the range of angles from the +X-axis that the spray cone can take (in degrees). The Z-component is ignored.
• Spray Cone Phi Range: Determines the range of angles from the +Z-axis that the spray cone can take (in degrees). The Z-component is ignored.
• Spray Linear Speed Range: Determines the range of linear speeds the particles can travel (in meters per second). The Z-component is ignored.
• Spray Angular Speed Range: Determines the range of angular speeds the particles can rotate (in degrees per second). The Z-component is ignored.
• Gravity Acceleration: Value changes the effect of gravity on the particles (in meters per second squared).
• Impact Events: This output is set automatically and used to drive the graphics from the Dynamics.
• World Transform: Not used.
• Parameters
  • Particle Limit: Sets a maximum number of particles to be used in the dust clouds.
  • Trigger Impulse: Acts as a tuning aid. If the box is checked, some particles will be emitted with the currently configured appearance. It can be used to tune and validate the parameters without having to actually dig.