3.51 Transform
Derived from Group.
Transform { |
Direct derived nodes: Solid.
3.51.1 Description
The Transform node is a grouping node that defines a coordinate system for its children that is relative to the coordinate systems of its parent.
3.51.2 Field Summary
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The translation field defines the translation from the parent coordinate system to the children's coordinate system.
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The rotation field defines an arbitrary rotation of the children's coordinate system with respect to the parent coordinate system. This field contains four floating point values: rx, ry, rz and α. The first three numbers, rx ry rz, define a normalized vector giving the direction of the axis around which the rotation must be carried out. The fourth value, α, specifies the rotation angle around the axis in radians. When α is zero, no rotation is carried out. All the values of the rotation field can be positive or negative. Note however that the length of the 3D vector rx ry rz must be normalized (i.e. its length is 1.0), otherwise the outcome of the simulation is undefined.
For example, a rotation of π/2 radians around the z-axis is represented like this:
A rotation of π radians around an axis located exactly between the x and y-axis is represented like this:rotation 0 0 1 1.5708
And finally, note that these two rotations are identical:rotation 0.7071 0.7071 0 3.1416rotation 0 1 0 -1.5708
rotation 0 -1 0 1.5708 -
The scale field specifies a possibly non-uniform scale. Only positive values are permitted; non-positive values scale are automatically reset to 1. Graphical objects support any positive non-uniform scale whereas physical objects are subjected to restrictions. This is so because scaled geometries must remain admissible for the physics engine collision detection. Restrictions for Geometries placed inside boundingObjects are as follows: Spheres and Capsules only support uniform scale; the scale coordinates x and z of a Transform with a Cylinder descendant must be the same. For the remaining Geometries, the scale is not restricted. The scale fields of a Solid node and its derived nodes must be uniform, i.e., of the form x x x so as to comply with the physics engine. For such nodes a positive scale field initially set to x y z is automatically reset to x x x. The same holds for a Transform placed inside a boundingObject and with a Sphere or a Capsule descendant. In the case of a Cylinder, x y z will be reset to x z x. If some value changes within one of the previous constrained scale fields, the two others are actuated using the new value and the corresponding constraint rule.
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