77 lines
2.5 KiB
Markdown
77 lines
2.5 KiB
Markdown
<h1>Walker Bone Control</h1>
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In this tutorial we describe how to manually control and animate the
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skeletons of walkers from the CARLA Python API. The reference of
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all classes and methods available can be found at
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[Python API reference](python_api.md).
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!!! note
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**This document assumes the user is familiar with the Python API**. <br>
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The user should read the Python API tutorial before reading this document.
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[Python API tutorial](python_api_tutorial.md).
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### Walker skeleton structure
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All walkers have the same skeleton hierarchy and bone names. Below is an image of the skeleton
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hierarchy.
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### How to manually control a walker's bones
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Following is a detailed step-by-step example of how to change the bone transforms of a walker
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from the CARLA Python API
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#### Connecting to the simulator
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Import neccessary libraries used in this example
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```py
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import carla
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import random
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```
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Initialize the carla client
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```py
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client = carla.Client('127.0.0.1', 2000)
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client.set_timeout(2.0)
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```
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#### Spawning a walker
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Spawn a random walker at one of the map's spawn points
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```py
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world = client.get_world()
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blueprint = random.choice(self.world.get_blueprint_library().filter('walker.*'))
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spawn_points = world.get_map().get_spawn_points()
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spawn_point = random.choice(spawn_points) if spawn_points else carla.Transform()
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world.try_spawn_actor(blueprint, spawn_point)
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```
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#### Controlling a walker's skeleton
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A walker's skeleton can be modified by passing an instance of the WalkerBoneControl class
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to the walker's apply_control function. The WalkerBoneControl class contains the transforms
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of the bones to be modified. Its bone_transforms member is a list of tuples of value pairs
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where the first value is the bone name and the second value is the bone transform. The
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apply_control function can be called on every tick to animate a walker's skeleton. The
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location and rotation of each transform is relative to its parent. Therefore when a
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parent bone's transform is modified, the transforms of the child bones in model space
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will also be changed relatively.
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In the example below, the rotations of the walker's hands are set to be 90 degrees around
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the forward axis and the locations are set to the origin.
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```py
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control = carla.WalkerBoneControl()
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first_tuple = ('crl_hand__R', carla.Transform(rotation=carla.Rotation(roll=90)))
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second_tuple = ('crl_hand__L', carla.Transform(rotation=carla.Rotation(roll=90)))
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control.bone_transforms = [first_tuple, second_tuple]
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world.player.apply_control(control)
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```
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