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2018-06-28T17:47:34Z

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2010年4月3日 (土) 11:19にwiki>Terrywallworkによる

2010-04-03T11:19:59Z

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=Constraints API=

==Purpose==

The Constraints API was started but development stalled out, so this page is intended as a place to work out the details which the users need.

==Overall Details of Constraints==

* The following types of constraints are implemented: Null, Copy Location, Copy Rotation, Copy Size, Track To, Floor, Locked Track, Follow Path, Stretch To, IK Solver, Action
* Objects and Poses can have constraints
* Only Poses can have IK Solver and Action constraints
* Constraints are applied in a particular order

For Armatures, Ton wrote a [http://www.blender.org/cms/How_Armatures_work.634.0.html nice description] of how armatures, poses and actions work together, which also describes constraints. [http://www.blender.org/cms/Action_and_NLA_editor.706.0.html Another page] describes Actions and NLAs; actions now also work with some non-armature objects.

==BPy Implementation Ideas==

Some of the ideas here are borrowed from the Modifier API (added to the API in version 2.42). If you aren't familiar with it, see [http://members.iinet.net.au/~cpbarton/ideasman/BPY_API/Modifier-module.html Cam's copy of the page]

===={{literal|BPy_ConstraintSeq}} Type====

Since an object or pose can have more than one constraint, we implement a sequence operator to access/manipulate the constraint stack. It basically defines
* a {{literal|PySequenceMethods}} structure for the index operator [],
* a {{literal|PyMethodDef}} structure for some instance methods, and
* (optionally) a {{literal|PyGetSetDef}} structure for any general attributes.

===={{literal|BPy_Constraint}} Type====

The Constraint type allows access to the data for a particular constraint. Since there are many types of constraints, we probably don't want to implement PyTypes for each. As is done for BPy Objects, a read-only attribute {{literal|type}} is defined for each {{literal|BPy_Constraint}} instance which identifies the type of Constraint and also determines what type of data is wrapped by the BPy object. The type definition contains
* a {{literal|PyMappingMethods}} structure for the mapping operator [],
* a {{literal|PyMethodDef}} structure for some instance methods, and
* a {{literal|PyGetSetDef}} structure for any general attributes
As is the case for the {{literal|BPy_Modifier}} type, the mapping operator [] is used to access the data particular to the Constraint type. For example, to access the "Offset" data for a {{literal|Floor}} constraint:

<source lang="python">from Blender import *

ob = Object.Get('Cube')
if len(ob.constraints) > 0:
const = ob.constraints[0]
if const.type == Constraint.Type.FLOOR:
offs = const[Constraint.Settings.OFFSET]
</source>

Or to print all the constraints attached to each bone in a pose:

<source lang="python">from Blender import *

ob = Object.Get('Armature')
pose = ob.getPose()
for bonename in pose.bones.keys():
bone = pose.bones[bonename]
for const in bone.constraints:
print bone.name
print '\t',const
</source>

======Object vs Pose Constriants======

Pose are unique in two ways:
* they can also have the two constraint types IK Solver and Action
* internally their data is stored within the object's {{literal|pose}} data instead of the {{literal|constraints}}
So they can't be referenced the same way; for an object, there is a sequence of constraints, but for a pose there is a sequence (of {{literal|poses}}) of sequence of constraints

[[Category:API's]]
[[Category:Development]]
[[Category:Script]]

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Yamyam: 1版 をインポートしました

2010年4月3日 (土) 11:19にwiki>Terrywallworkによる

Yamyam: 1版をインポートしました