86 lines
3.8 KiB
ReStructuredText
86 lines
3.8 KiB
ReStructuredText
.. _doc_ragdoll_system:
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Ragdoll system
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==============
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Introduction
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------------
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Since version 3.1, Godot supports ragdoll physics. Ragdolls rely on physics simulation to create realistic procedural animation. They are used for death animations in many games.
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In this tutorial, we will be using the Platformer3D demo to set up a ragdoll.
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.. note:: You can download the Platformer3D demo on `GitHub <https://github.com/godotengine/godot-demo-projects/tree/master/3d/platformer>`_ or using the `Asset Library <https://godotengine.org/asset-library/asset/125>`_.
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Setting up the ragdoll
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----------------------
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Creating physical bones
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~~~~~~~~~~~~~~~~~~~~~~~
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Like many other features in the engine, there is a node to set up a ragdoll: the :ref:`PhysicalBone <class_PhysicalBone>` node. To simplify the setup, you can generate ``PhysicalBone`` nodes with the "Create physical skeleton" feature in the skeleton node.
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Open the platformer demo in Godot, and then the Robi scene. Select the ``Skeleton`` node. A skeleton button appears on the top bar menu:
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.. image:: img/ragdoll_menu.png
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Click it and select the ``Create physical skeleton`` option. Godot will generate ``PhysicalBone`` nodes and collision shapes for each bone in the skeleton and pin joints to connect them together:
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.. image:: img/ragdoll_bones.png
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Some of the generated bones aren't necessary: the ``MASTER`` bone for example. So we're going to clean up the skeleton by removing them.
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Cleaning up the skeleton
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~~~~~~~~~~~~~~~~~~~~~~~~
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Each ``PhysicalBone`` the engine needs to simulate has a performance cost, so you want to remove every bone that is too small to make a difference in the simulation, as well as all utility bones.
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For example, if we take a humanoid, you do not want to have physical bones for each finger. You can use a single bone for the entire hand instead, or one for the palm, one for the thumb, and a last one for the other four fingers.
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Remove these physical bones: ``MASTER``, ``waist``, ``neck``, ``headtracker``. This gives us an optimized skeleton and makes it easier to control the ragdoll.
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Collision shape adjustment
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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The next task is adjusting the collision shape and the size of physical bones to match the part of the body that each bone should simulate.
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.. image:: img/ragdoll_shape_adjust.gif
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Joints adjustment
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~~~~~~~~~~~~~~~~~
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Once you adjusted the collision shapes, your ragdoll is almost ready. You just want to adjust the pin joints to get a better simulation. ``PhysicalBone`` nodes have an unconstrained pin joint assigned to them by default. To change the pin joint, select the ``PhysicalBone`` and change the constraint type in the ``Joint`` section. There, you can change the constraint's orientation and its limits.
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.. image:: img/ragdoll_joint_adjust.gif
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This is the final result:
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.. image:: img/ragdoll_result.png
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Simulating the ragdoll
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----------------------
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The ragdoll is now ready to use. To start the simulation and play the ragdoll animation, you need to call the ``physical_bones_start_simulation`` method. Attach a script to the skeleton node and call the method in the ``_ready`` method:
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.. tabs::
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.. code-tab:: gdscript GDScript
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func _ready():
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physical_bones_start_simulation()
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To stop the simulation, call the ``physical_bones_stop_simulation()`` method.
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.. image:: img/ragdoll_sim_stop.gif
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You can also limit the simulation to only a few bones. To do so, pass the bone names as a parameter. Here's an example of partial ragdoll simulation:
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.. image:: img/ ragdoll_sim_part.gif
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Collision layer and mask
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~~~~~~~~~~~~~~~~~~~~~~~~
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Make sure to set up your collision layers and masks properly so the ``KinematicBody``'s capsule doesn't get in the way of the physics simulation:
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.. image:: img/ragdoll_layer.png
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For more information, read :ref:`doc_physics_introduction_collision_layers_and_masks`.
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