net.minecraft.block.Trapdoor in Beta 1.7.3, BIN mappings. This is a scratch file to show the effective changes that my mixins create to Gun Man, who maintains the base class edit version.

Trapdoor.java

package net.minecraft.block;

import net.fabricmc.api.EnvType;
import net.fabricmc.api.Environment;
import net.minecraft.block.material.Material;
import net.minecraft.entity.Living;
import net.minecraft.entity.player.PlayerBase;
import net.minecraft.level.Level;
import net.minecraft.level.TileView;
import net.minecraft.util.hit.HitResult;
import net.minecraft.util.maths.Box;
import net.minecraft.util.maths.MathHelper;
import net.minecraft.util.maths.Vec3f;

public class Trapdoor extends BlockBase {
    protected Trapdoor(int i, Material arg) {
        super(i, arg);
        this.texture = 84;
        if (arg == Material.METAL) {
            ++this.texture;
        }

        float var3 = 0.5F;
        float var4 = 1.0F;
        this.setBoundingBox(0.5F - var3, 0.0F, 0.5F - var3, 0.5F + var3, var4, 0.5F + var3);
    }

    //SlightlyBetterTrapdoors
    private boolean doPlayerBasedRotation;

    public boolean isFullOpaque() {
        return false;
    }

    public boolean isFullCube() {
        return false;
    }

    @Environment(EnvType.CLIENT)
    public int getRenderType() {
        return 0;
    }

    @Environment(EnvType.CLIENT)
    public Box getOutlineShape(Level level, int x, int y, int z) {
        this.updateBoundingBox(level, x, y, z);
        return super.getOutlineShape(level, x, y, z);
    }

    public Box getCollisionShape(Level level, int x, int y, int z) {
        this.updateBoundingBox(level, x, y, z);
        return super.getCollisionShape(level, x, y, z);
    }

    public void updateBoundingBox(TileView tileView, int x, int y, int z) {
        this.method_1060(tileView.getTileMeta(x, y, z));
    }

    @Environment(EnvType.CLIENT)
    public void method_1605() {
        float var1 = 0.1875F;
        this.setBoundingBox(0.0F, 0.5F - var1 / 2.0F, 0.0F, 1.0F, 0.5F + var1 / 2.0F, 1.0F);
    }

    public void method_1060(int i) {
        float var2 = 0.1875F;
        this.setBoundingBox(0.0F, 0.0F, 0.0F, 1.0F, var2, 1.0F);
        if (method_1061(i)) {
            if ((i & 3) == 0) {
                this.setBoundingBox(0.0F, 0.0F, 1.0F - var2, 1.0F, 1.0F, 1.0F);
            }

            if ((i & 3) == 1) {
                this.setBoundingBox(0.0F, 0.0F, 0.0F, 1.0F, 1.0F, var2);
            }

            if ((i & 3) == 2) {
                this.setBoundingBox(1.0F - var2, 0.0F, 0.0F, 1.0F, 1.0F, 1.0F);
            }

            if ((i & 3) == 3) {
                this.setBoundingBox(0.0F, 0.0F, 0.0F, var2, 1.0F, 1.0F);
            }
        }

    }

    public void activate(Level level, int x, int y, int z, PlayerBase player) {
        this.canUse(level, x, y, z, player);
    }

    public boolean canUse(Level level, int x, int y, int z, PlayerBase player) {
        if (this.material == Material.METAL) {
            return true;
        } else {
            int var6 = level.getTileMeta(x, y, z);
            level.setTileMeta(x, y, z, var6 ^ 4);
            level.playLevelEvent(player, 1003, x, y, z, 0);
            return true;
        }
    }

    public void method_1059(Level arg, int i, int j, int k, boolean flag) {
        int var6 = arg.getTileMeta(i, j, k);
        boolean var7 = (var6 & 4) > 0;
        if (var7 != flag) {
            arg.setTileMeta(i, j, k, var6 ^ 4);
            arg.playLevelEvent((PlayerBase)null, 1003, i, j, k, 0);
        }
    }

    //SlightlyBetterTrapdoors
    public void onAdjacentBlockUpdate(Level level, int x, int y, int z, int id) {
        if (!level.isClient) {
            int var6 = level.getTileMeta(x, y, z);
            int var7 = x;
            int var8 = z;
            if ((var6 & 3) == 0) {
                var8 = z + 1;
            }

            if ((var6 & 3) == 1) {
                --var8;
            }

            if ((var6 & 3) == 2) {
                var7 = x + 1;
            }

            if ((var6 & 3) == 3) {
                --var7;
            }

            if (id > 0 && BlockBase.BY_ID[id].getEmitsRedstonePower()) {
                boolean var9 = level.hasRedstonePower(x, y, z);
                this.method_1059(level, x, y, z, var9);
            }

        }
    }

    public HitResult method_1564(Level arg, int i, int j, int k, Vec3f arg1, Vec3f arg2) {
        this.updateBoundingBox(arg, i, j, k);
        return super.method_1564(arg, i, j, k, arg1, arg2);
    }

    public void onBlockPlaced(Level level, int x, int y, int z, int facing) {
        byte var6 = 0;
        if (facing == 2) {
            var6 = 0;
        }

        if (facing == 3) {
            var6 = 1;
        }

        if (facing == 4) {
            var6 = 2;
        }

        if (facing == 5) {
            var6 = 3;
        }

        level.setTileMeta(x, y, z, var6);
    }

    //SlightlyBetterTrapdoors
    public boolean canPlaceAt(Level level, int x, int y, int z, int meta) {
        if (meta == 0 || meta == 1) {
            doPlayerBasedRotation = true;
        }

            return true;
        }

    public void afterPlaced(Level level, int x, int y, int z, Living living) {
        if (doPlayerBasedRotation) {
            int rotation = MathHelper.floor((double) (living.yaw * 4.0F / 360.0F) + 0.5D) & 3;
            int[] magic = {0, 3, 1, 2};
            level.setTileMeta(x, y, z, magic[rotation]);
        }
    }  

    public static boolean method_1061(int i) {
        return (i & 4) != 0;
    }
}