com.gempukku.libgdx.graph.pipeline.producer.postprocessor.GaussianBlurKernel Maven / Gradle / Ivy

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package com.gempukku.libgdx.graph.pipeline.producer.postprocessor;

public class GaussianBlurKernel {
    private static final int MAX_BLUR_RADIUS = 64;
    private static final float[][] kernelCache = new float[1 + MAX_BLUR_RADIUS][];

    private static final float SIGMA_HELPER = 3.5676f;

    private GaussianBlurKernel() {
    }

    public static float[] getKernel(int blurRadius) {
        blurRadius = Math.min(MAX_BLUR_RADIUS, blurRadius);
        if (kernelCache[blurRadius] == null) {
            float[] kernel = GaussianBlurKernel.create1DBlurKernel(blurRadius);
            kernelCache[blurRadius] = new float[1 + MAX_BLUR_RADIUS];
            System.arraycopy(kernel, 0, kernelCache[blurRadius], 0, kernel.length);
        }
        return kernelCache[blurRadius];
    }

    public static float[] create1DBlurKernel(int size) {
        float[] result = new float[1 + size];
        float sigma = size / SIGMA_HELPER;
        float norm = 1f / ((float) Math.sqrt(2 * Math.PI) * sigma);
        float coeff = 2 * sigma * sigma;
        float total = 0;
        for (int i = 0; i <= size; i++) {
            float value = norm * (float) Math.exp(-i * i / coeff);
            result[i] = value;
            total += value;
            if (i > 0)
                total += value;
        }
        for (int i = 0; i <= size; i++) {
            result[i] /= total;
        }
        return result;
    }
}