Physics_interpolation In Combination With CPUParticles2D And Emitting = False Prevents Position Update Of Child Node

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Physics Interpolation in Combination with CPUParticles2D and Emitting = False Prevents Position Update of Child Node

Introduction

In this article, we will delve into a peculiar issue that arises when using the physics_interpolation feature in combination with the CPUParticles2D node in Godot. Specifically, we will explore how setting emitting to false prevents the position update of the child node. We will also provide a minimal reproduction project (MRP) to help developers reproduce and understand this issue.

Tested Versions

The issue has been reproduced in the following versions:

  • Godot 4.4.stable-mono

System Information

The system information for the test environment is as follows:

  • Godot version: 4.4.stable.mono
  • Operating System: Windows 11 (build 26100)
  • Multi-window setup with 3 monitors
  • Graphics API: Vulkan (Forward+)
  • Dedicated NVIDIA GeForce RTX 4090 (NVIDIA; 32.0.15.7216)
  • Processor: AMD Ryzen 5 5600X 6-Core Processor (12 threads)

Issue Description

The issue arises when using the CPUParticles2D node in combination with the physics_interpolation feature. When the emitting property is set to false, the position update of the child node is prevented. This is a critical issue, as it can lead to unexpected behavior and inconsistencies in the game or application.

To illustrate this issue, let's consider a simple scenario:

  • We have a CharacterBody2D node as the parent node.
  • The CharacterBody2D node has a child node, which is a CPUParticles2D node.
  • When we move the CharacterBody2D node, we would expect the CPUParticles2D node to move with it.
  • However, when we enable physics_interpolation, the CPUParticles2D node stays at the origin and does not move with the CharacterBody2D node.

Steps to Reproduce

To reproduce this issue, follow these steps:

  1. Run the attached project.
  2. Use the A/D keys to move the CharacterBody2D node.

Minimal Reproduction Project (MRP)

The behavior can be reproduced with the following project:

bug-particle.zip

Analysis

The issue arises due to the interaction between the physics_interpolation feature and the CPUParticles2D node. When physics_interpolation is enabled, the position update of the child node is prevented. This is because the CPUParticles2D node is not designed to handle physics interpolation.

To mitigate this issue, we can enable the emitting property of the CPUParticles2D node. However, this is not always an option, as it can lead to unexpected behavior and inconsistencies in the game or application.

Conclusion

In conclusion, the issue of physics_interpolation in combination with CPUParticles2D and emitting = false preventing position update of child node is a critical issue that needs to be addressed. We have provided a minimal reproduction project (MRP) to help developers reproduce and understand this issue. We hope that this article will help developers identify and fix this issue, and provide a better gaming experience for users.

Workarounds

While we wait for a fix from the Godot team, here are some workarounds that can help mitigate this issue:

  • Disable physics_interpolation when using CPUParticles2D nodes.
  • Enable the emitting property of the CPUParticles2D node, but be aware of the potential consequences.
  • Use a different particle system, such as the SpriteParticles2D node, which is designed to handle physics interpolation.

Future Development

We hope that the Godot team will address this issue in future updates. In the meantime, we will continue to provide workarounds and solutions to help developers overcome this issue.

Related Issues

This issue is related to other issues in Godot, such as:

We hope that this article will help developers identify and fix this issue, and provide a better gaming experience for users.
Physics Interpolation in Combination with CPUParticles2D and Emitting = False Prevents Position Update of Child Node: Q&A

Introduction

In our previous article, we explored the issue of physics_interpolation in combination with CPUParticles2D and emitting = false preventing position update of child node. We also provided a minimal reproduction project (MRP) to help developers reproduce and understand this issue. In this article, we will answer some frequently asked questions (FAQs) related to this issue.

Q: What is the cause of this issue?

A: The issue arises due to the interaction between the physics_interpolation feature and the CPUParticles2D node. When physics_interpolation is enabled, the position update of the child node is prevented.

Q: How can I reproduce this issue?

A: To reproduce this issue, follow these steps:

  1. Run the attached project.
  2. Use the A/D keys to move the CharacterBody2D node.

Q: What are the system requirements to reproduce this issue?

A: The system requirements to reproduce this issue are:

  • Godot version: 4.4.stable.mono
  • Operating System: Windows 11 (build 26100)
  • Multi-window setup with 3 monitors
  • Graphics API: Vulkan (Forward+)
  • Dedicated NVIDIA GeForce RTX 4090 (NVIDIA; 32.0.15.7216)
  • Processor: AMD Ryzen 5 5600X 6-Core Processor (12 threads)

Q: What are the workarounds for this issue?

A: While we wait for a fix from the Godot team, here are some workarounds that can help mitigate this issue:

  • Disable physics_interpolation when using CPUParticles2D nodes.
  • Enable the emitting property of the CPUParticles2D node, but be aware of the potential consequences.
  • Use a different particle system, such as the SpriteParticles2D node, which is designed to handle physics interpolation.

Q: Is this issue specific to Godot 4.4.stable.mono?

A: No, this issue is not specific to Godot 4.4.stable.mono. It can occur in other versions of Godot as well.

Q: Can I use a different particle system to avoid this issue?

A: Yes, you can use a different particle system, such as the SpriteParticles2D node, which is designed to handle physics interpolation.

Q: Will this issue be fixed in future updates?

A: We hope that the Godot team will address this issue in future updates. In the meantime, we will continue to provide workarounds and solutions to help developers overcome this issue.

Q: Are there any related issues in Godot?

A: Yes, this issue is related to other issues in Godot, such as:

Q: Can I contribute to the solution of this issue?

A: Yes, you can contribute to the solution of this issue by reporting it to the Godot team, providing a minimal reproduction project (MRP), and helping to debug the issue.

Conclusion

In conclusion, the issue of physics_interpolation in combination with CPUParticles2D and emitting = false preventing position update of child node is a critical issue that needs to be addressed. We hope that this Q&A article will help developers understand and overcome this issue. We will continue to provide updates and workarounds until the issue is fixed.