With the Live Parts™ for SOLIDWORKS Add-in, users can leverage gradients to define constraints for your Live Parts design. You can define two types gradients:
- Attractor gradients (blue in Live Parts) define volumes that are filled in by cells in the final Live Parts design
- Repeller gradients (red in Live Parts) define volumes that keep out cells in the final Live Parts design
Attractor and repeller gradients can be defined by referencing existing, complex solid body geometries within an assembly or by creating new complex or primitive shapes (e.g. rectangular prisms, cylinders with optional through-holes, and spheres with optional cavities).
- Select Gradient in the Live Parts for SOLIDWORKS Add-in toolbar.
- Click on the Volume box and select the geometry in your SOLIDWORKS assembly to define your gradient's volume.
- Use the Type drop-down list to select your gradient type (attractor or repeller).
- (Optional) Check Smoothable to fully smooth the triangle vertices of the cells within the confines of the gradient. If this option is not checked, then triangle vertices are snapped to the geometry of the gradient.
- (Optional) Check Is Fixed to fix the gradient in space. Fixing a gradient prevents it (and any attached seed cells) from falling to the floor during the growth process in Live Parts due to gravitational or other user-defined forces. Every Live Parts model must have at least one fixed gradient, typically associated with the seed cell start location.
- (Optional) Select a pre-defined force to apply to the gradient from the Forces drop-down list and click Add. You may remove an applied force by clicking on it in the box below or remove all of the applied forces by clicking Clear Selections.
- (Optional) For each force you apply to the gradient, choose whether the Force Surface is inner, outer, or other and whether the Force Application is a push, pull, or both.
- Click the Checkmark as the top of the gradient side menu.
Notes on gradients:
- Repeller gradients can intersect attractor gradients, which causes the cells to fill out the attractor gradients as much as possible while still keeping out of the repeller gradients.
- When applying a force to a gradient with complex geometry, users should select the “outside” option for applying the force. Live Parts will then apply the force to all surfaces that can feel it depending on its direction - for example, if a force is directed downward, then the force will be applied to all cells within the gradient that are exposed to the downward force.
- If a gradient with complex geometry contains features smaller than the size of the cells, then these features will be lost during the Live Parts growth process.
- Live Parts uses the term gradients in reference to the use of chemical signals — morphogens — for plant cell communication. Morphogens diffuse throughout the cell medium luring cells to proliferation regions ("attractor gradients") and pushing them away from keep out regions ("repeller gradients"). In plants, these gradient fields can work together: if plant cells are growing towards an attractor gradient, the stem will simultaneously avoid repeller gradients obstructing the pathway to the stem's end location.