Tracking Mouse Movement in React with Raycaster

Описание: Learn how to accurately track mouse movement with raycaster in React applications using Three.js, overcoming common issues with precision.
---
This video is based on the question https://stackoverflow.com/q/74173361/ asked by the user 'Jack Duffy' ( https://stackoverflow.com/u/18030965/ ) and on the answer https://stackoverflow.com/a/74198951/ provided by the user 'Jack Duffy' ( https://stackoverflow.com/u/18030965/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: React how to better track mouse movement on raycaster

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Tracking Mouse Movement in React with Raycaster: A Comprehensive Guide

When developing applications using React and Three.js, particularly those involving 3D interactions, precise mouse tracking is crucial. A common challenge developers encounter is ensuring that mouse coordinates correspond accurately to the 3D space, especially when dealing with DOM elements that scroll. If you've ever faced issues with raycasting where the mouse interacts with the wrong part of your scene, you're not alone! In this guide, we’ll explore how to fine-tune your mouse tracking for better functionality and user experience when working with 3D planes in React applications.

Understanding the Problem

Imagine you have a 3D plane rendered in your React application using Three.js. The setup works seamlessly when the plane takes up the entire viewport. However, problems arise when you scroll down a webpage. If your mouse is hovering over the plane but you're only halfway down the page, the effects triggered by the mouse movement do not correlate correctly with the mouse's actual position. Instead, the interaction appears to respond to the plane's original position in the viewport.

Here's how your current implementation calculates mouse positions:

[[See Video to Reveal this Text or Code Snippet]]

This method calculates the mouse's position based on the window's dimensions. However, it does not account for the scrolling position of the page, leading to incorrect interaction points.

A Solution to Accurate Mouse Tracking

To solve this issue, you'll need to adjust your mouse coordinates by calculating the mouse's actual position relative to the element rather than the entire window.

Step 1: Get the Bounding Rectangle

The first step is to retrieve the bounding rectangle of the DOM element that contains your plane. The getBoundingClientRect() method provides valuable data, including the dimensions and the position of the element relative to the viewport.

Step 2: Update the Mouse Position Calculation

Instead of using the window dimensions to calculate mouse coordinates, subtract the bounds of the target DOM element. Here’s how to implement this adjusted calculation:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Rendering and Raycasting

Finally, you can continue to use the request for animation as before:

[[See Video to Reveal this Text or Code Snippet]]

Benefits of This Approach

Accuracy: By referencing the correct bounding rectangle, your mouse coordinates directly correspond to the region of interest, eliminating any discrepancies caused by scrolling.

Performance: The refinement keeps your rendering loop lightweight since you only adjust coordinates once based on the element's position.

User Experience: Ensuring that interactions feel natural and responsive enhances the overall user experience of your application.

Conclusion

Employing accurate mouse position tracking in your React applications enhances interactions within Three.js, paving the way for a more engaging user experience. By following the steps outlined above, you can confidently address the issues arising from discrepancies between the mouse's visual position and its interaction point within your 3D scene. Try implementing these techniques in your next project to see the difference they make!

With this improved approach, you'll be able to create more immersive and intuitive user interfaces that maximize the potential of your 3D graphics built with React and Three.js.