src/game/java/net/minecraft/client/renderer/texture/OverlayTexture.java

package net.minecraft.client.renderer.texture;

import com.mojang.blaze3d.platform.NativeImage;
import com.mojang.blaze3d.systems.RenderSystem;
import net.minecraft.util.ARGB;
import net.minecraftforge.api.distmarker.Dist;
import net.minecraftforge.api.distmarker.OnlyIn;

@OnlyIn(Dist.CLIENT)
public class OverlayTexture implements AutoCloseable {
    private static final int SIZE = 16;
    public static final int NO_WHITE_U = 0;
    public static final int RED_OVERLAY_V = 3;
    public static final int WHITE_OVERLAY_V = 10;
    public static final int NO_OVERLAY = pack(0, 10);
    private final DynamicTexture texture = new DynamicTexture(16, 16, false);

    public OverlayTexture() {
        NativeImage nativeimage = this.texture.getPixels();

        for (int i = 0; i < 16; i++) {
            for (int j = 0; j < 16; j++) {
                if (i < 8) {
                    nativeimage.setPixel(j, i, -1291911168);
                } else {
                    int k = (int)((1.0F - (float)j / 15.0F * 0.75F) * 255.0F);
                    nativeimage.setPixel(j, i, ARGB.color(k, -1));
                }
            }
        }

        RenderSystem.activeTexture(33985);
        this.texture.bind();
        this.texture.setFilter(false, false);
        this.texture.setClamp(true);
        nativeimage.upload(0, 0, 0, 0, 0, nativeimage.getWidth(), nativeimage.getHeight(), false);
        RenderSystem.activeTexture(33984);
    }

    @Override
    public void close() {
        this.texture.close();
    }

    public void setupOverlayColor() {
        RenderSystem.setupOverlayColor(this.texture.getId(), 16);
    }

    public static int u(float p_118089_) {
        return (int)(p_118089_ * 15.0F);
    }

    public static int v(boolean p_118097_) {
        return p_118097_ ? 3 : 10;
    }

    public static int pack(int p_118094_, int p_118095_) {
        return p_118094_ | p_118095_ << 16;
    }

    public static int pack(float p_118091_, boolean p_118092_) {
        return pack(u(p_118091_), v(p_118092_));
    }

    public void teardownOverlayColor() {
        RenderSystem.teardownOverlayColor();
    }
}