93 lines
3.6 KiB
Markdown
93 lines
3.6 KiB
Markdown
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# Mixed timing scenarios with fixed and dynamic input
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There are some situations where you might set the Update Mode **process in Dynamic Update** even when using input code in `FixedUpdate`, to minimize input latency, as described in the [previous section](./timing-optimize-fixed-update.md).
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In this situation, for discrete events you must ensure that you use [`WasPressedThisFrame`](../api/UnityEngine.InputSystem.InputAction.html#UnityEngine_InputSystem_InputAction_WasPressedThisFrame_) or [`WasReleasedThisFrame`](../api/UnityEngine.InputSystem.InputAction.html#UnityEngine_InputSystem_InputAction_WasReleasedThisFrame_) in `Update`, and pass through a variable to your `FixedUpdate` code to indicate the event happened. There may still be some latency between the frame in which the event occurred, and the next `FixedUpdate` call.
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For example:
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```c#
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using UnityEngine;
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using UnityEngine.InputSystem;
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public class ExampleScript : MonoBehaviour
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{
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InputAction jumpAction;
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bool jumpPressed;
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private void Start()
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{
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jumpAction = InputSystem.actions.FindAction("Jump");
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}
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private void Update()
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{
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// read discrete jump pressed event here:
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if (jumpAction.WasPressedThisFrame())
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{
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// set this variable to true, for use in FixedUpdate
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jumpPressed = true;
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}
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}
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void FixedUpdate()
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{
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if (jumpPressed)
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{
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// apply jump physics here
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// set the variable to false so that the jump pressed physics are only applied once
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jumpPressed = false;
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}
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}
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}
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```
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## Minimum latency in mixed timing scenarios
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A technique to give the user the feel of absolute minimum latency while still using `FixedUpdate` is to respond as fast as possible in `Update` giving some visual feedback, but also respond to that same input in `FixedUpdate` for your physics system code. For example, you could display the start of a "jump" animation immediately in `Update`, while applying physics to correspond with the "jump" animation in the next available `FixedUpdate` which might come slightly later.
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In this scenario, set your Update Mode **Process events in Dynamic Update** which gives you the fastest response in your `Update` call. However for the reasons mentioned in the previous section, this might mean you miss discrete events if you use methods like [`WasPressedThisFrame`](../api/UnityEngine.InputSystem.InputAction.html#UnityEngine_InputSystem_InputAction_WasPressedThisFrame_) in your `FixedUpdate` call. To avoid this problem, use a variable to pass through the pressed/released state of the discrete event from the event handler to your FixedUpdate call, and then clear it once your FixedUpdate code has acted on it. For example:
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```c#
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using UnityEngine;
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using UnityEngine.InputSystem;
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public class ExampleScript : MonoBehaviour
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{
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InputAction jumpAction;
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bool jumpPressed;
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private void Start()
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{
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jumpAction = InputSystem.actions.FindAction("Jump");
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}
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private void Update()
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{
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// at high FPS, it’s fastest to read actions here:
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// read discrete jump pressed event here:
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if (jumpAction.WasPressedThisFrame())
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{
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// start jump animation here
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// set this variable to true, for use in FixedUpdate
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jumpPressed = true;
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}
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}
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void FixedUpdate()
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{
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if (jumpPressed)
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{
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// apply jump physics here
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// set the variable to false so that the jump pressed physics are only applied once
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jumpPressed = false;
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}
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}
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}
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```
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