Line Intersection Detection in React Three Fiber

There are a few issues with your current approach to detecting clicks on a line in React Three Fiber:

Key Issues

1. The Line component from @react-three/drei is likely using the newer Line2 implementation under the hood, which behaves differently from the basic Line class in Three.js.

2. React Three Fiber has its own event system that differs from manually setting up raycasting as you're doing.

Solutions

Option 1: Use LineSegments2 instead

The Line2 and LineSegments2 classes in Three.js provide better line rendering with proper width and better interaction:

JAVASCRIPTCopied
import { Line } from '@react-three/drei'
import { useThree } from '@react-three/fiber'
import React from 'react'
import { Vector3 } from 'three'

const Interaction = () => {
    // Let R3F handle the raycasting
    const { raycaster } = useThree()
    
    // Increase the threshold for all lines
    raycaster.params.Line.threshold = 0.2
    
    return (
        <Line
            points={[new Vector3(3, 3, 3), new Vector3(1, 1, 1)]}
            color='pink'
            lineWidth={2}
            // Use R3F's built-in event system
            onClick={(e) => {
                e.stopPropagation()
                console.log('Line clicked!', e)
            }}
        />
    )
}

export default Interaction

Option 2: Use a custom approach with Line2

If you need more control, you can use the Line2 class directly:

JAVASCRIPTCopied
import { useThree } from '@react-three/fiber'
import React, { useRef, useMemo } from 'react'
import { Vector3 } from 'three'
import { Line2 } from 'three/examples/jsm/lines/Line2.js'
import { LineGeometry } from 'three/examples/jsm/lines/LineGeometry.js'
import { LineMaterial } from 'three/examples/jsm/lines/LineMaterial.js'

const CustomLine = () => {
    const { size } = useThree()
    const lineRef = useRef()
    
    // Create geometry and material
    const [geometry, material] = useMemo(() => {
        const points = [new Vector3(3, 3, 3), new Vector3(1, 1, 1)]
        const positions = []
        
        points.forEach(point => {
            positions.push(point.x, point.y, point.z)
        })
        
        const geo = new LineGeometry()
        geo.setPositions(positions)
        
        const mat = new LineMaterial({
            color: 'pink',
            linewidth: 0.005, // Line2 uses resolution-independent width
            resolution: new Vector2(size.width, size.height)
        })
        
        return [geo, mat]
    }, [size])
    
    return (
        <primitive 
            object={new Line2(geometry, material)} 
            ref={lineRef}
            onClick={(e) => {
                e.stopPropagation()
                console.log('Line clicked!', e)
            }}
        />
    )
}

Important Notes

1. The drei Line component already handles a lot of the complexity for you, so Option 1 is generally preferred.

2. Make sure your camera is positioned correctly to see the line.

3. The threshold parameter is crucial for line detection - you might need to experiment with different values.

4. React Three Fiber's event system automatically handles raycasting, so your manual raycasting setup is likely conflicting with it.

5. Consider using <mesh> with a thin cylinder geometry if you need more reliable click detection on lines.

Try these approaches and see if they improve your line interaction experience.