path: root/tools/spectral_editor/curve.js

// Curve.js - Object-oriented curve management with spectrogram caching
// This eliminates redundant drawCurveToSpectrogram() calls by caching spectrograms

class Curve {
    constructor(id, dctSize, numFrames) {
        // Identity
        this.id = id;

        // Curve data
        this.controlPoints = [];  // [{frame, freqHz, amplitude}]
        this.profile = {
            type: 'gaussian',
            sigma: 30.0,
            param2: 0.0  // For future profile types
        };

        // Visual properties
        this.color = '#0e639c';  // Default blue
        this.volume = 1.0;

        // Spectrogram dimensions
        this.dctSize = dctSize;
        this.numFrames = numFrames;

        // Cache management
        this.dirty = true;
        this.cachedSpectrogram = null;
    }

    // ============================================================================
    // Cache Management
    // ============================================================================

    markDirty() {
        this.dirty = true;
    }

    getSpectrogram() {
        if (!this.dirty && this.cachedSpectrogram) {
            return this.cachedSpectrogram;
        }

        // Recompute spectrogram
        this.cachedSpectrogram = this.computeSpectrogram();
        this.dirty = false;
        return this.cachedSpectrogram;
    }

    // Force recalculation (useful when dimensions change)
    invalidateCache() {
        this.dirty = true;
        this.cachedSpectrogram = null;
    }

    // Update dimensions (called when reference audio changes)
    setDimensions(dctSize, numFrames) {
        if (this.dctSize !== dctSize || this.numFrames !== numFrames) {
            this.dctSize = dctSize;
            this.numFrames = numFrames;
            this.invalidateCache();
        }
    }

    // ============================================================================
    // Control Point Management
    // ============================================================================

    addControlPoint(point) {
        this.controlPoints.push({ ...point });
        this.markDirty();
    }

    updateControlPoint(idx, point) {
        if (idx >= 0 && idx < this.controlPoints.length) {
            this.controlPoints[idx] = { ...point };
            this.markDirty();
        }
    }

    deleteControlPoint(idx) {
        if (idx >= 0 && idx < this.controlPoints.length) {
            this.controlPoints.splice(idx, 1);
            this.markDirty();
        }
    }

    setControlPoints(points) {
        this.controlPoints = points.map(p => ({ ...p }));
        this.markDirty();
    }

    // ============================================================================
    // Profile Management
    // ============================================================================

    setProfile(profileType, sigma, param2 = 0.0) {
        const changed = this.profile.type !== profileType ||
                       this.profile.sigma !== sigma ||
                       this.profile.param2 !== param2;

        if (changed) {
            this.profile.type = profileType;
            this.profile.sigma = sigma;
            this.profile.param2 = param2;
            this.markDirty();
        }
    }

    setProfileType(profileType) {
        if (this.profile.type !== profileType) {
            this.profile.type = profileType;
            this.markDirty();
        }
    }

    setProfileSigma(sigma) {
        if (this.profile.sigma !== sigma) {
            this.profile.sigma = sigma;
            this.markDirty();
        }
    }

    // ============================================================================
    // Visual Properties
    // ============================================================================

    setColor(color) {
        this.color = color;
        // Note: Color changes don't affect spectrogram, only visual rendering
        // So we don't mark dirty
    }

    setVolume(volume) {
        if (this.volume !== volume) {
            this.volume = volume;
            this.markDirty();
        }
    }

    // ============================================================================
    // Spectrogram Generation (Core Algorithm)
    // ============================================================================

    computeSpectrogram() {
        const spectrogram = new Float32Array(this.dctSize * this.numFrames);

        if (this.controlPoints.length === 0) {
            return spectrogram;
        }

        // Find the frame range covered by control points
        const frames = this.controlPoints.map(p => p.frame);
        const minFrame = Math.max(0, Math.min(...frames));
        const maxFrame = Math.min(this.numFrames - 1, Math.max(...frames));

        // Constants (same as original drawCurveToSpectrogram)
        const AMPLITUDE_SCALE = 50.0;
        const SAMPLE_RATE = 32000;

        // Apply curve volume
        const curveVolume = this.volume;

        // Only iterate over the range where control points exist
        for (let frame = minFrame; frame <= maxFrame; frame++) {
            // Evaluate Bezier curve at this frame
            const freqHz = this.evaluateBezierLinear('freqHz', frame);
            const amplitude = this.evaluateBezierLinear('amplitude', frame);

            // Convert freq to bin
            const freqBin0 = (freqHz / (SAMPLE_RATE / 2)) * this.dctSize;

            // Apply vertical profile
            for (let bin = 0; bin < this.dctSize; bin++) {
                const dist = Math.abs(bin - freqBin0);
                const profileValue = this.evaluateProfile(dist);

                const value = amplitude * profileValue * AMPLITUDE_SCALE * curveVolume;
                const idx = frame * this.dctSize + bin;
                spectrogram[idx] += value;
            }
        }

        return spectrogram;
    }

    // ============================================================================
    // Bezier Evaluation (Linear Interpolation)
    // ============================================================================

    evaluateBezierLinear(property, targetFrame) {
        const points = this.controlPoints;

        if (points.length === 0) return 0;
        if (points.length === 1) return points[0][property];

        // Sort points by frame (ascending)
        const sorted = [...points].sort((a, b) => a.frame - b.frame);

        // Find the two control points that bracket targetFrame
        let p0 = sorted[0];
        let p1 = sorted[sorted.length - 1];

        for (let i = 0; i < sorted.length - 1; i++) {
            if (targetFrame >= sorted[i].frame && targetFrame <= sorted[i + 1].frame) {
                p0 = sorted[i];
                p1 = sorted[i + 1];
                break;
            }
        }

        // Clamp to endpoints if outside range
        if (targetFrame < sorted[0].frame) return sorted[0][property];
        if (targetFrame > sorted[sorted.length - 1].frame) return sorted[sorted.length - 1][property];

        // Linear interpolation
        const t = (targetFrame - p0.frame) / (p1.frame - p0.frame);
        return p0[property] * (1 - t) + p1[property] * t;
    }

    // ============================================================================
    // Profile Evaluation
    // ============================================================================

    evaluateProfile(dist) {
        switch (this.profile.type) {
            case 'gaussian':
                return this.evaluateGaussian(dist);
            case 'decaying_sinusoid':
                return this.evaluateDecayingSinusoid(dist);
            case 'noise':
                return this.evaluateNoise(dist);
            default:
                return this.evaluateGaussian(dist);
        }
    }

    evaluateGaussian(dist) {
        const sigma = this.profile.sigma;
        const exponent = -(dist * dist) / (2 * sigma * sigma);
        return Math.exp(exponent);
    }

    evaluateDecayingSinusoid(dist) {
        const sigma = this.profile.sigma;
        const freq = 0.5;  // Fixed frequency for now
        const envelope = Math.exp(-(dist * dist) / (2 * sigma * sigma));
        const wave = Math.cos(2 * Math.PI * freq * dist);
        return envelope * wave * 0.5 + envelope * 0.5;  // Bias to positive
    }

    evaluateNoise(dist) {
        const sigma = this.profile.sigma;
        const envelope = Math.exp(-(dist * dist) / (2 * sigma * sigma));
        // Simple pseudo-random based on distance
        const noise = Math.sin(dist * 12.9898 + dist * 78.233) * 0.5 + 0.5;
        return envelope * noise;
    }

    // ============================================================================
    // Serialization (for save/load)
    // ============================================================================

    toJSON() {
        return {
            id: this.id,
            controlPoints: this.controlPoints,
            profile: this.profile,
            color: this.color,
            volume: this.volume
        };
    }

    static fromJSON(json, dctSize, numFrames) {
        const curve = new Curve(json.id, dctSize, numFrames);
        curve.controlPoints = json.controlPoints || [];
        curve.profile = json.profile || { type: 'gaussian', sigma: 30.0, param2: 0.0 };
        curve.color = json.color || '#0e639c';
        curve.volume = json.volume || 1.0;
        curve.markDirty();  // Force recomputation on load
        return curve;
    }
}