Extracting Data from VideoTexture in Three.js

Based on the available documentation, there isn't a direct method in Three.js to extract pixel data from a VideoTexture without some form of rendering or processing. However, you can achieve this by using a combination of Three.js and the HTML5 Canvas API.

The approach would be similar to the one mentioned in the post about extracting data from DataTexture, but with some adjustments for video content:

1. Create a hidden canvas element
2. Draw the current video frame to the canvas
3. Use the canvas context's getImageData() method to access pixel data
4. Process this data to extract brightness values or other information

Here's a basic implementation:

JAVASCRIPTCopied
// Create a VideoTexture
const video = document.createElement('video');
video.src = 'path/to/your/video.mp4';
video.autoplay = true;
video.loop = true;
video.muted = true; // Often needed for autoplay
video.play();

const videoTexture = new THREE.VideoTexture(video);
videoTexture.minFilter = THREE.LinearFilter;
videoTexture.magFilter = THREE.LinearFilter;

// Create a hidden canvas for pixel extraction
const canvas = document.createElement('canvas');
const context = canvas.getContext('2d');
canvas.width = video.videoWidth || 640;  // Set appropriate size
canvas.height = video.videoHeight || 480;

// Function to extract pixel data
function extractPixelData() {
    // Make sure video is playing and has dimensions
    if (video.readyState < video.HAVE_CURRENT_DATA || !video.videoWidth) {
        return null;
    }
    
    // Draw the current video frame to canvas
    context.drawImage(video, 0, 0, canvas.width, canvas.height);
    
    // Get pixel data
    const imageData = context.getImageData(0, 0, canvas.width, canvas.height);
    const pixels = imageData.data;
    
    // Process pixel data (example: calculate brightness)
    // You can modify this to extract whatever data you need
    const brightnessMap = [];
    for (let i = 0; i < pixels.length; i += 4) {
        const r = pixels[i];
        const g = pixels[i + 1];
        const b = pixels[i + 2];
        // Simple brightness formula (you might want a more accurate one)
        const brightness = (r + g + b) / 3;
        brightnessMap.push(brightness);
    }
    
    return brightnessMap;
}

// Use in animation loop
function animate() {
    requestAnimationFrame(animate);
    
    // Update the texture if video is playing
    if (videoTexture) videoTexture.needsUpdate = true;
    
    // Extract pixel data and use it
    const brightnessData = extractPixelData();
    if (brightnessData) {
        // Use brightness data to drive object positions
        // For example, sample specific points in your brightness map
        // and use those values to position objects
    }
    
    renderer.render(scene, camera);
}

This approach gives you access to the raw pixel data from each video frame, which you can then process to drive object positioning or other properties in your scene.

Note that this method does involve some processing overhead, so you might want to:

• Extract data at a lower frequency than your render loop
• Sample only specific pixels rather than the entire frame
• Consider downscaling the canvas for faster processing