Fix buckets. (and any other raytraced items)

src/main/java/com/minelittlepony/client/HorseCam.java

@@ -0,0 +1,94 @@
+package com.minelittlepony.client;
+
+import net.minecraft.client.MinecraftClient;
+import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.util.hit.HitResult;
+import net.minecraft.util.math.Vec3d;
+
+import com.minelittlepony.pony.IPony;
+import com.minelittlepony.settings.PonySettings;
+
+public class HorseCam {
+    /**
+     * Transforms the client pony's pitch to the corresponding angle for a human character.
+     */
+    public static float transformCameraAngle(float pitch) {
+
+        if (!PonySettings.FILLYCAM.get()) {
+            return pitch;
+        }
+
+        PlayerEntity player = MinecraftClient.getInstance().player;
+        IPony pony = MineLittlePony.getInstance().getManager().getPony(player);
+
+        if (!pony.getRace(false).isHuman()) {
+            float factor = pony.getMetadata().getSize().getEyeHeightFactor();
+            return rescaleCameraPitch(player.getStandingEyeHeight() / factor, pitch);
+        }
+
+        return pitch;
+    }
+
+    /**
+     * Calculates a corresponding camera pitch for the current player at
+     * the specified character height.
+     *
+     * @param toHeight      Target height.
+     * @param originalPitch Original, unchanged pitch.
+     *
+     * @return The new pitch value, otherwise the original value passed in.
+     */
+    public static float rescaleCameraPitch(double toHeight, float originalPitch) {
+        /*     -90
+         *     |
+         *     ---------------0
+         *     |
+         *     90
+         */
+        /*  A                A - toHeight
+         *  |\               B - fromHeight
+         *  |?\              y - headPitch
+         *  |  \             ? - result
+         *  |   \            C - raytrace
+         *  B-   \
+         *  |y -  \
+         *  |    - \         Tan(?) = horDist / toHeight
+         *  |-------C            ?  = arcTan(horDist / toHeight);
+         *   horDist
+         */
+        MinecraftClient client = MinecraftClient.getInstance();
+        PlayerEntity player = client.player;
+        HitResult hit = client.hitResult;
+
+        // noop
+        if (hit == null || player == null) {
+            return originalPitch;
+        }
+
+        // Small angles aren't worth changing.
+        // Helps with bows, arrows, and projectiles.
+        if (Math.abs(originalPitch) < 10) {
+            return originalPitch;
+        }
+
+        Vec3d hitPos = hit.getPos();
+        Vec3d pos = player.getPos();
+
+        double diffX = Math.abs(hitPos.x - pos.x);
+        double diffZ = Math.abs(hitPos.z - pos.z);
+        double horDist = Math.sqrt(diffX * diffX + diffZ * diffZ);
+
+        float theta = (float)Math.atan(horDist / toHeight);
+
+        // convert to degress
+        theta /= Math.PI / 180;
+
+        // convert to vertical pitch (-90 to 90).
+        // Preserve up/down direction.
+        float newPitch = (90 - theta) * Math.signum(originalPitch);
+
+        System.out.println("From " + originalPitch + " to " + newPitch);
+
+        return newPitch;
+    }
+}

src/main/java/com/minelittlepony/client/mixin/MixinPlayerMoveC2SPacket_Both.java

@@ -0,0 +1,19 @@
+package com.minelittlepony.client.mixin;
+
+import net.minecraft.server.network.packet.PlayerMoveC2SPacket;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import com.minelittlepony.client.HorseCam;
+
+@Mixin(PlayerMoveC2SPacket.Both.class)
+public abstract class MixinPlayerMoveC2SPacket_Both extends PlayerMoveC2SPacket {
+    @Inject(method = "<init>(DDDFFZ)V",
+            at = @At("RETURN"))
+    private void onInit(CallbackInfo info) {
+        this.pitch = HorseCam.transformCameraAngle(this.pitch);
+    }
+}

src/main/java/com/minelittlepony/client/mixin/MixinPlayerMoveC2SPacket_LookOnly.java

@@ -0,0 +1,19 @@
+package com.minelittlepony.client.mixin;
+
+import net.minecraft.server.network.packet.PlayerMoveC2SPacket;
+
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import com.minelittlepony.client.HorseCam;
+
+@Mixin(PlayerMoveC2SPacket.LookOnly.class)
+public abstract class MixinPlayerMoveC2SPacket_LookOnly extends PlayerMoveC2SPacket {
+    @Inject(method = "<init>(FFZ)V",
+            at = @At("RETURN"))
+    private void onInit(CallbackInfo info) {
+        this.pitch = HorseCam.transformCameraAngle(this.pitch);
+    }
+}

src/main/resources/minelp.mixin.json

@@ -12,6 +12,8 @@
         "MixinFirstPersonRenderer",
         "MixinGlStateManager",
         "MixinItemRenderer",
-        "MixinClientPlayerEntity"
+        "MixinClientPlayerEntity",
+        "MixinPlayerMoveC2SPacket_Both",
+        "MixinPlayerMoveC2SPacket_LookOnly"
     ]
 }