minecraft_25w45a_unobfuscated/net/minecraft/client/renderer/texture/MipmapGenerator.java

/*
 * Decompiled with CFR 0.152.
 */
package net.minecraft.client.renderer.texture;

import com.mojang.blaze3d.platform.NativeImage;
import com.mojang.blaze3d.platform.TextureUtil;
import net.minecraft.client.renderer.texture.MipmapStrategy;
import net.minecraft.resources.Identifier;
import net.minecraft.util.ARGB;

public class MipmapGenerator {
    private static final String ITEM_PREFIX = "item/";
    private static final float ALPHA_CUTOFF = 0.2f;
    private static final float STRICT_ALPHA_CUTOFF = 0.6f;
    private static final int ALPHA_CUTOUT_CUTOFF = 96;

    private MipmapGenerator() {
    }

    public static NativeImage[] generateMipLevels(Identifier name, NativeImage[] currentMips, int newMipLevel, MipmapStrategy mipmapStrategy) {
        if (newMipLevel + 1 <= currentMips.length) {
            return currentMips;
        }
        NativeImage[] result = new NativeImage[newMipLevel + 1];
        if (mipmapStrategy == MipmapStrategy.AUTO) {
            if (name.getPath().startsWith(ITEM_PREFIX)) {
                mipmapStrategy = MipmapStrategy.STRICT_CUTOUT;
            } else {
                MipmapStrategy mipmapStrategy2 = mipmapStrategy = MipmapGenerator.hasTransparentPixel(currentMips[0]) ? MipmapStrategy.CUTOUT : MipmapStrategy.MEAN;
            }
        }
        if (currentMips.length == 1 && (mipmapStrategy == MipmapStrategy.CUTOUT || mipmapStrategy == MipmapStrategy.STRICT_CUTOUT)) {
            TextureUtil.solidify(currentMips[0]);
        }
        result[0] = currentMips[0];
        for (int level = 1; level <= newMipLevel; ++level) {
            if (level < currentMips.length) {
                result[level] = currentMips[level];
                continue;
            }
            NativeImage lastData = result[level - 1];
            NativeImage data = new NativeImage(lastData.getWidth() >> 1, lastData.getHeight() >> 1, false);
            int width = data.getWidth();
            int height = data.getHeight();
            for (int x = 0; x < width; ++x) {
                for (int y = 0; y < height; ++y) {
                    int color;
                    if (mipmapStrategy == MipmapStrategy.MEAN || mipmapStrategy == MipmapStrategy.DARK_CUTOUT) {
                        int color1 = lastData.getPixel(x * 2 + 0, y * 2 + 0);
                        int color2 = lastData.getPixel(x * 2 + 1, y * 2 + 0);
                        int color3 = lastData.getPixel(x * 2 + 0, y * 2 + 1);
                        int color4 = lastData.getPixel(x * 2 + 1, y * 2 + 1);
                        color = mipmapStrategy == MipmapStrategy.DARK_CUTOUT ? MipmapGenerator.darkenedAlphaBlend(color1, color2, color3, color4) : ARGB.meanLinear(color1, color2, color3, color4);
                    } else {
                        color = MipmapGenerator.alphaBlend(x, y, result[0], level, mipmapStrategy);
                    }
                    data.setPixel(x, y, color);
                }
            }
            result[level] = data;
        }
        return result;
    }

    private static boolean hasTransparentPixel(NativeImage image) {
        for (int x = 0; x < image.getWidth(); ++x) {
            for (int y = 0; y < image.getHeight(); ++y) {
                if (ARGB.alpha(image.getPixel(x, y)) != 0) continue;
                return true;
            }
        }
        return false;
    }

    private static int darkenedAlphaBlend(int color1, int color2, int color3, int color4) {
        float aTotal = 0.0f;
        float rTotal = 0.0f;
        float gTotal = 0.0f;
        float bTotal = 0.0f;
        if (ARGB.alpha(color1) != 0) {
            aTotal += ARGB.srgbToLinearChannel(ARGB.alpha(color1));
            rTotal += ARGB.srgbToLinearChannel(ARGB.red(color1));
            gTotal += ARGB.srgbToLinearChannel(ARGB.green(color1));
            bTotal += ARGB.srgbToLinearChannel(ARGB.blue(color1));
        }
        if (ARGB.alpha(color2) != 0) {
            aTotal += ARGB.srgbToLinearChannel(ARGB.alpha(color2));
            rTotal += ARGB.srgbToLinearChannel(ARGB.red(color2));
            gTotal += ARGB.srgbToLinearChannel(ARGB.green(color2));
            bTotal += ARGB.srgbToLinearChannel(ARGB.blue(color2));
        }
        if (ARGB.alpha(color3) != 0) {
            aTotal += ARGB.srgbToLinearChannel(ARGB.alpha(color3));
            rTotal += ARGB.srgbToLinearChannel(ARGB.red(color3));
            gTotal += ARGB.srgbToLinearChannel(ARGB.green(color3));
            bTotal += ARGB.srgbToLinearChannel(ARGB.blue(color3));
        }
        if (ARGB.alpha(color4) != 0) {
            aTotal += ARGB.srgbToLinearChannel(ARGB.alpha(color4));
            rTotal += ARGB.srgbToLinearChannel(ARGB.red(color4));
            gTotal += ARGB.srgbToLinearChannel(ARGB.green(color4));
            bTotal += ARGB.srgbToLinearChannel(ARGB.blue(color4));
        }
        rTotal /= 4.0f;
        gTotal /= 4.0f;
        bTotal /= 4.0f;
        int finalAlpha = ARGB.linearToSrgbChannel(aTotal /= 4.0f);
        if (finalAlpha < 96) {
            finalAlpha = 0;
        }
        return ARGB.color(finalAlpha, ARGB.linearToSrgbChannel(rTotal), ARGB.linearToSrgbChannel(gTotal), ARGB.linearToSrgbChannel(bTotal));
    }

    private static int alphaBlend(int x, int y, NativeImage originalImage, int level, MipmapStrategy mipmapStrategy) {
        float resultAlpha;
        float[] accumulated = new float[7];
        int size = 1 << level;
        for (int xOrig = x * size; xOrig < x * size + size; ++xOrig) {
            for (int yOrig = y * size; yOrig < y * size + size; ++yOrig) {
                MipmapGenerator.accumulate(originalImage.getPixel(xOrig, yOrig), accumulated);
            }
        }
        float alphaTotal = accumulated[0];
        float resultRed = accumulated[1] / alphaTotal;
        float resultGreen = accumulated[2] / alphaTotal;
        float resultBlue = accumulated[3] / alphaTotal;
        alphaTotal /= (float)(size * size);
        float f = mipmapStrategy == MipmapStrategy.STRICT_CUTOUT ? 0.6f : 0.2f;
        if (alphaTotal < f) {
            resultAlpha = 0.0f;
            resultRed = accumulated[4] / (float)(size * size);
            resultGreen = accumulated[5] / (float)(size * size);
            resultBlue = accumulated[6] / (float)(size * size);
        } else {
            resultAlpha = 1.0f;
        }
        return ARGB.color(resultAlpha, ARGB.color(ARGB.linearToSrgbChannel(resultRed), ARGB.linearToSrgbChannel(resultGreen), ARGB.linearToSrgbChannel(resultBlue)));
    }

    private static void accumulate(int color, float[] accumulated) {
        float alpha = ARGB.alphaFloat(color);
        accumulated[0] = accumulated[0] + alpha;
        float red = ARGB.srgbToLinearChannel(ARGB.red(color));
        accumulated[1] = accumulated[1] + red * alpha;
        accumulated[4] = accumulated[4] + red;
        float green = ARGB.srgbToLinearChannel(ARGB.green(color));
        accumulated[2] = accumulated[2] + green * alpha;
        accumulated[5] = accumulated[5] + green;
        float blue = ARGB.srgbToLinearChannel(ARGB.blue(color));
        accumulated[3] = accumulated[3] + blue * alpha;
        accumulated[6] = accumulated[6] + blue;
    }
}