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Usage
Click the rigid button to activate it. The shape of all splines of the active solid will now be preserved. Changing the position of one spline point will cause the whole spline-skin to move in the same direction as one rigid object. It is still possible to change the spline curve (through the tangent vectors) and the skin. The rigid option overrides the kinematic option.
Comments
A rigid spline that is a branch cannot be rotated as a rigid object by changing the tangent vector of the parent spline point. Make it non-rigid and non-kinematic to do this.
See also
branches, spline tangent, kinematic
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Usage
Click the kinematic button to activate it. The distance between the spline points of all splines of the active solid will now be preserved resulting in kinematic behaviour. Changing the position of one spline point will cause the other spline points to move along (by restoring the original distance between adjacent points). By fixing the different positions of one spline point in key-frames, the whole spline can be animated through inverse kinematics. This works for individual splines as well as splines connected through the branches mechanism.
The kinematic option works best in conjunction with auto orient.
Comments
Animation through forward kinematics is achieved by setting the angles at the spline points in skeleton editing mode. Inverse kinematics in combination with locks and angle constraints can slow down interaction. Even though all the spline points are fixed in key-frames, animation with or without kinematics will look different for the in-between frames.
Sometimes it is useful to use kinematics only when fixing the key-frames, and to switch it off before playing the animation. Whenever during interpolation between key frames undesired behaviour occurs, try adding keyframes in between. It is possible to create situations of kinematics in combination with locked points that are unsolvable for the kinematic solver. In that case locked points will let loose.
See also
branches, constraints, fix, play
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Usage
Click the auto orient button to activate it. The tangent vectors of the spline points of all splines in the active solid are now computed by the program. The vectors are set to retain a proper spline when moving with inverse kinematics or otherwise.
Comments
Very useful in combination with kinematic and/or auto length.
See also
kinematic, auto length
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Usage
Click the auto length button to activate it. The length of the tangent vectors of the spline points of all splines in the active solid are now computed by the program.
Comments
Very useful when moving spline points along the spline for uniform skins.
See also
uniform skin
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Usage
Click the free branches button to activate it. All branches in the active solid are now allowed to freely rotate around their parent point while moving the parent or branches. To control their rotation, lock the parent point by selecting it and pressing lock point. Now the red colored branch can be selected and rotated around the parent point by moving it around. All other branches of the same parent will rotate along. By fixing the red colored branch at different positions while rotating it, rotation of branches around their parent point can be animated.
Comments
By default the free branches button is not active to prevent unwanted rotational behaviour of branches while moving spline points.
See also
branches, lock point
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Usage
Make the model into the start shape for simulations and click the dynamic button to activate it. When dynamic is activated the current state of the model is used for resetting it when using reset dynamic. Dynamic splines have a sub-menu with dynamics options in the points box. In spline and skeleton modes, the dynamic laws animate the spline points; in skin mode the skin points are dynamically animated. Each dynamic point can be subject to physical forces, including gravity and vector fields. The points are connected to their neighbors with springs in order to maintain the initial shape of the spline or skin. The full springs toggle in the points box can be used to construct springs between all points involved, instead of making springs only between neighbors (the dynamic values reset when this button is clicked).
The dynamics slider in the points box shows how the selected point is animated: with key-frames (value 0.0), or with dynamics (value 1.0), or with a mix of these two methods. By default, all points are key-framed. If the dynamics value of one or more points is made larger than 0.0, a label will appear to show that dynamics are on for this spline or skin. The point icons in the points box graphically shows these dynamic values using a black color to indicate the amount of dynamics for each point.
Clicking the simulate button will show the effect of physical forces on the dynamic points. Auto-orient, auto-length, kinematic, rigid, branches, connections, etc. still work for dynamic spline points.
While simulating, all points can still be moved around by the user. Try making one point not dynamic (value 0.0) and move this one around while simulating. This results in dynamic points reacting on these movements. This effect can also be recorded into a keyframed animation by using record.
Comments
A spline-skin object with a dynamic spline or skin has a behavior similar to any particle system in the Particles interface. This means that all kinds of parameters can be set, such as gravity and resilience. It is even possible to attach particle fields and collision objects to a dynamic spline-skin. If collisions are used, the radius parameter determines the minimal distance that a dynamic spline or skin point is allowed to have from the collision object. The default setting of dynamic skins and splines has some gravity which will result in the dynamic points being pulled down. This can be changed in the Particles menu. See the Particles manual pages for more information.
The springs have their own parameters (spring, damp) in the Particles interface. If there are many skin points, a full set of dynamic springs will be slow to evaluate. Full dynamic skins of more than 10 by 10 skin points will need careful tuning of the spring parameters. The dynamic button is available only if a license exists for the Particles interface.
See also
simulate, Particles, particle interface, reset simulation, Points box , dynamics, record
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Usage
Click the constraints button to activate it. Splines with constraints on will be checked for constraints on their rotation angles. The effect of these constraints becomes apparent if kinematic points move in such a way that the angles run outside their constrained intervals. In these cases, the other spline points will move as well, attempting to find a configuration in which all the rotation angle constraints are satisfied.
Use of constraints makes sense only for kinematic splines. In skeleton editing mode, the points box shows the values of the angles from the selected spline points orientation towards the next spline point (the angles at the last spline point can be set, but are not used). Because the constraints button is on, entry boxes for x, y and z angles show the minimum and maximum values of the local angles. The constrained intervals are shown as black regions on the circles that correspond to the rotation axes (shown only in skeleton editing mode with the global/local toggle on local angles). The angle constraints also apply directly to the angles, for example when these are changed by picking and dragging a rotation axis.
Comments
If many constraints are set, moving one spline point can cause the program to offer a solution for the other spline points that does not appear immediately intuitive. Many constraints can slow down interactions in the graphical user interface. Because the local x, y and z angles are applied one after the other (actually first y, then z, then x), a z angle of 90 degrees will cause the x and the y axes to point in the same direction. In some cases this can confuse the constraint solver.
See also
skeleton, Points box , angles, global/local,min,max, kinematic, rotate x, rotate y, rotate z
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