Creating View-Independent Line Glow Effects in Three.js

The issue you're experiencing with the LineMaterial from Line2 is a common challenge when working with view-dependent UV coordinates. The vUv.x value changes based on the viewing angle, causing your glow effect to distort when the camera perspective changes.

Solution Approach

Since post-processing is not an option, you'll need to modify your shader approach to create a view-independent glow effect. Here are some techniques you can try:

1. Use Distance from Line Center

Instead of relying on vUv.x, calculate the distance from the center of the line in the fragment shader:

GLSLCopied
varying vec2 vUv;
uniform float lineWidth;

void main() {
    // Calculate normalized distance from center (0.0 to 1.0)
    float distFromCenter = abs(vUv.x - 0.5) * 2.0;
    
    // Create glow effect based on distance
    float glow = 1.0 - pow(distFromCenter, 2.0);
    
    // Apply glow to color
    vec3 glowColor = vec3(1.0, 0.5, 0.2); // Example color
    gl_FragColor = vec4(glowColor * glow, glow);
}

2. Use View-Space Calculations

A more robust approach is to calculate the glow based on view-space coordinates:

GLSLCopied
varying vec3 vViewPosition;
varying vec2 vUv;
uniform float lineWidth;

void main() {
    // Calculate distance from line center in view space
    float distFromCenter = abs(vUv.x - 0.5) * 2.0;
    
    // Adjust for viewing angle (this is the key part)
    vec3 viewDir = normalize(vViewPosition);
    float viewFactor = abs(dot(viewDir, vec3(0.0, 0.0, 1.0)));
    
    // Compensate for perspective distortion
    distFromCenter = mix(distFromCenter, distFromCenter * viewFactor, 0.8);
    
    // Create glow effect
    float glow = 1.0 - pow(distFromCenter, 2.0);
    
    // Apply glow to color
    vec3 glowColor = vec3(1.0, 0.5, 0.2);
    gl_FragColor = vec4(glowColor * glow, glow);
}

3. Custom LineMaterial Extension

You can extend the LineMaterial to include custom shader chunks:

JAVASCRIPTCopied
// Create a custom line material that extends LineMaterial
class GlowLineMaterial extends THREE.LineMaterial {
    constructor(parameters) {
        super(parameters);
        
        // Override fragment shader to include view-independent glow
        this.onBeforeCompile = (shader) => {
            shader.fragmentShader = shader.fragmentShader.replace(
                'void main() {',
                `
                uniform float glowIntensity;
                uniform vec3 glowColor;
                
                void main() {
                    // Calculate view-independent distance from center
                    float distFromCenter = abs(vUv.x - 0.5) * 2.0;
                    float glow = 1.0 - pow(distFromCenter, 2.0);
                `
            );
            
            shader.fragmentShader = shader.fragmentShader.replace(
                'gl_FragColor = vec4( outgoingLight, diffuseColor.a );',
                'gl_FragColor = vec4( mix(outgoingLight, glowColor, glow * glowIntensity), diffuseColor.a );'
            );
            
            // Add custom uniforms
            shader.uniforms.glowIntensity = { value: 0.8 };
            shader.uniforms.glowColor = { value: new THREE.Color(1.0, 0.5, 0.2) };
            
            // Store references to custom uniforms
            this.uniforms = shader.uniforms;
        };
    }
    
    // Add methods to control glow
    setGlowIntensity(value) {
        if (this.uniforms) this.uniforms.glowIntensity.value = value;
    }
    
    setGlowColor(color) {
        if (this.uniforms) this.uniforms.glowColor.value = color;
    }
}

4. Use ShaderMaterial with Line2

If you need more control, you can create a completely custom shader:

JAVASCRIPTCopied
const material = new THREE.ShaderMaterial({
    uniforms: {
        color: { value: new THREE.Color(0xffffff) },
        linewidth: { value: 5.0 },
        resolution: { value: new THREE.Vector2(window.innerWidth, window.innerHeight) },
        glowColor: { value: new THREE.Color(1.0, 0.5, 0.2) },
        glowIntensity: { value: 0.8 }
    },
    vertexShader: `
        attribute vec3 position;
        attribute vec2 uv;
        
        uniform mat4 modelViewMatrix;
        uniform mat4 projectionMatrix;
        
        varying vec2 vUv;
        varying vec3 vViewPosition;
        
        void main() {
            vUv = uv;
            vec4 mvPosition = modelViewMatrix * vec4(position, 1.0);
            vViewPosition = -mvPosition.xyz;
            gl_Position = projectionMatrix * mvPosition;
        }
    `,
    fragmentShader: `
        uniform vec3 color;
        uniform vec3 glowColor;
        uniform float glowIntensity;
        
        varying vec2 vUv;
        varying vec3 vViewPosition;
        
        void main() {
            // Calculate view-independent distance from center
            float distFromCenter = abs(vUv.x - 0.5) * 2.0;
            
            // Adjust for viewing angle
            vec3 viewDir = normalize(vViewPosition);
            float viewFactor = abs(dot(viewDir, vec3(0.0, 0.0, 1.0)));
            distFromCenter = mix(distFromCenter, distFromCenter * viewFactor, 0.8);
            
            // Create glow effect
            float glow = 1.0 - pow(distFromCenter, 2.0);
            
            // Mix base color with glow
            vec3 finalColor = mix(color, glowColor, glow * glowIntensity);
            gl_FragColor = vec4(finalColor, 1.0);
        }
    `,
    transparent: true,
    side: THREE.DoubleSide
});

Implementation Considerations

1. You'll need to ensure your shader has access to the view position or direction to compensate for the viewing angle.

2. Test different glow functions (linear, quadratic, exponential) to find the most visually appealing result.

3. Consider adding parameters to control the glow width and intensity for fine-tuning.

4. If performance is a concern, start with the simpler approaches and only move to more complex solutions if needed.

These approaches should help you achieve a more consistent glow effect that remains stable regardless of the viewing angle, without requiring post-processing effects.

Three.js Fluid Animation Implementation

Based on the information provided, I can help explain how fluid animations might be implemented in Three.js, though I don't have specific information about the exact implementation used on the website you mentioned.

For fluid animations in Three.js, there are several approaches that could be used:

Animation Components in Three.js

Three.js provides several animation-related classes that could be used for creating fluid effects:

• AnimationMixer: Acts as a player for animations
• AnimationClip: Contains animation data
• AnimationAction: Controls the playback of a specific clip
• KeyframeTrack: Tracks how a specific property changes over time

Loading Animations

If the fluid animation is pre-created, it might be loaded using the AnimationLoader:

JAVASCRIPTCopied
// Instantiate a loader
const loader = new THREE.AnimationLoader();

// Load the animation resource
loader.load(
  // Resource URL
  'animations/fluid-animation.js',
  // onLoad callback
  function (animations) {
    // animations is an array of AnimationClips
    // These can be applied to objects in the scene
  },
  // onProgress callback
  function (xhr) {
    console.log((xhr.loaded / xhr.total * 100) + '% loaded');
  },
  // onError callback
  function (err) {
    console.log('An error happened');
  }
);

Common Approaches for Fluid Animations

While I don't have specific information about the implementation on the website you mentioned, here are some common approaches for creating fluid animations in Three.js:

1. Shader-based fluid simulations: Using GLSL shaders to simulate fluid dynamics
2. Particle systems: Using many small particles with physics to simulate fluid behavior
3. Mesh deformation: Animating vertex positions of a mesh to create flowing effects
4. Pre-rendered animations: Using pre-created animation clips

For similar examples, you might want to explore Three.js examples related to shaders, particle systems, or custom animation implementations.

If you need more specific guidance, examining the actual code in the static/js/lib directory would be necessary to understand the exact implementation approach used on that website.