Fix mixins and rewrite dimension changing

src/main/java/com/minelittlepony/unicopia/entity/player/GravityDelegate.java

@@ -5,17 +5,14 @@ import java.util.Random;
 import com.minelittlepony.unicopia.Race;
 import com.minelittlepony.unicopia.USounds;
 import com.minelittlepony.unicopia.ability.FlightPredicate;
-import com.minelittlepony.unicopia.ability.HeightPredicate;
 import com.minelittlepony.unicopia.entity.FlightControl;
 import com.minelittlepony.unicopia.entity.Updatable;
 import com.minelittlepony.unicopia.magic.MagicEffect;
-import com.minelittlepony.unicopia.mixin.MixinEntity;
 import com.minelittlepony.unicopia.particles.MagicParticleEffect;
 import com.minelittlepony.unicopia.util.NbtSerialisable;
 import com.minelittlepony.unicopia.util.MutableVector;
 
 import net.minecraft.entity.Entity;
-import net.minecraft.entity.EntityPose;
 import net.minecraft.entity.player.PlayerEntity;
 import net.minecraft.nbt.CompoundTag;
 import net.minecraft.sound.SoundCategory;
@@ -25,9 +22,9 @@ import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.MathHelper;
 import net.minecraft.util.math.Vec3d;
 
-public class GravityDelegate implements Updatable, FlightControl, NbtSerialisable, FlightPredicate, HeightPredicate {
+public class GravityDelegate implements Updatable, FlightControl, NbtSerialisable, FlightPredicate {
 
-    private final Pony player;
+    final Pony player;
 
     private static final float MAXIMUM_FLIGHT_EXPERIENCE = 1500;
 
@@ -42,10 +39,11 @@ public class GravityDelegate implements Updatable, FlightControl, NbtSerialisabl
 
     private float gravity = 0;
 
-    private float eyeHeight;
+    private final PlayerDimensionsDelegate dimensions;
 
     public GravityDelegate(Pony player) {
         this.player = player;
+        this.dimensions = new PlayerDimensionsDelegate(this);
     }
 
     @Override
@@ -64,53 +62,12 @@ public class GravityDelegate implements Updatable, FlightControl, NbtSerialisabl
         return player.getSpecies().canFly();
     }
 
-    protected boolean isRainboom(Pony player) {
+    protected boolean isRainboom() {
         return Math.sqrt(getHorizontalMotion(player.getOwner())) > 0.4F;
     }
 
-    public float getEyeHeight() {
+    public PlayerDimensionsDelegate getDimensions() {
-        return eyeHeight;
+        return dimensions;
-    }
-
-    @Override
-    public float getTargetEyeHeight(Pony player) {
-        if (player.hasEffect()) {
-            MagicEffect effect = player.getEffect();
-            if (!effect.isDead() && effect instanceof HeightPredicate) {
-                float val = ((HeightPredicate)effect).getTargetEyeHeight(player);
-                if (val > 0) {
-                    return val;
-                }
-            }
-        }
-
-        if (isFlying && isRainboom(player)) {
-            return 0.5F;
-        }
-
-        EntityPose pose = player.getOwner().getPose();
-        return player.getOwner().getActiveEyeHeight(pose, player.getOwner().getDimensions(pose));
-    }
-
-    @Override
-    public float getTargetBodyHeight(Pony player) {
-        if (player.hasEffect()) {
-            MagicEffect effect = player.getEffect();
-            if (!effect.isDead() && effect instanceof HeightPredicate) {
-                float val = ((HeightPredicate)effect).getTargetBodyHeight(player);
-                if (val > 0) {
-                    return val;
-                }
-            }
-        }
-
-        // Player height is reset at this point, so we can use it as our baseline.
-
-        if (isFlying && isRainboom(player)) {
-            return player.getOwner().getHeight() / 2;
-        }
-
-        return player.getOwner().getHeight();
     }
 
     public void setGraviationConstant(float constant) {
@@ -170,26 +127,8 @@ public class GravityDelegate implements Updatable, FlightControl, NbtSerialisabl
             }
         }
 
-        float bodyHeight = getTargetBodyHeight(player);
+        if (dimensions.update()) {
-        eyeHeight = 0;
+            player.getOwner().calculateDimensions();
-        eyeHeight = getTargetEyeHeight(player);
-
-        if (gravity < 0) {
-            eyeHeight = bodyHeight - eyeHeight;
-        }
-
-        if (entity.age > 10) {
-            bodyHeight = player.getInterpolator().interpolate("standingHeight", bodyHeight, 10);
-            eyeHeight = player.getInterpolator().interpolate("eyeHeight", eyeHeight, 10);
-        }
-
-
-        ((MixinEntity)entity).setSize(entity.getWidth(), bodyHeight);
-
-        if (gravity < 0) {
-            if (entity.isSneaking()) {
-                //entity.eyeHeight += 0.2F;
-            }
         }
 
         if (!entity.abilities.creativeMode && !entity.isFallFlying()) {
@@ -228,7 +167,7 @@ public class GravityDelegate implements Updatable, FlightControl, NbtSerialisabl
                         player.addEnergy(2);
                     }
 
-                    if (isRainbooming || (entity.isSneaking() && isRainboom(player))) {
+                    if (isRainbooming || (entity.isSneaking() && isRainboom())) {
                         float forward = 0.5F * flightExperience / MAXIMUM_FLIGHT_EXPERIENCE;
 
                         velocity.x += - forward * MathHelper.sin(entity.yaw * 0.017453292F);

src/main/java/com/minelittlepony/unicopia/entity/player/PlayerDimensionsDelegate.java

@@ -0,0 +1,96 @@
+package com.minelittlepony.unicopia.entity.player;
+
+import com.minelittlepony.unicopia.ability.HeightPredicate;
+import com.minelittlepony.unicopia.magic.MagicEffect;
+
+import net.minecraft.entity.EntityDimensions;
+import net.minecraft.entity.EntityPose;
+
+public final class PlayerDimensionsDelegate {
+
+    private float defaultEyeHeight;
+    private float defaultBodyHeight;
+
+    private float lastTargetEyeHeight;
+    private float lastTargetBodyHeight;
+
+    private final GravityDelegate gravity;
+
+    public PlayerDimensionsDelegate(GravityDelegate gravity) {
+        this.gravity = gravity;
+    }
+
+    public float getActiveEyeHeight(float original) {
+        defaultEyeHeight = original;
+        return calculateTargetEyeHeightWithGravity(calculateTargetBodyHeight());
+    }
+
+    public EntityDimensions getDimensions(EntityPose pos, EntityDimensions dimensions) {
+        defaultBodyHeight = dimensions.height;
+        return EntityDimensions.changing(dimensions.width, calculateTargetBodyHeight());
+    }
+
+    boolean update() {
+        float targetBodyHeight = calculateTargetBodyHeight();
+        float targetEyeHeight = calculateTargetEyeHeightWithGravity(targetBodyHeight);
+
+        if (targetEyeHeight != lastTargetEyeHeight || targetBodyHeight != lastTargetBodyHeight) {
+            lastTargetBodyHeight = targetBodyHeight;
+            lastTargetEyeHeight = targetEyeHeight;
+            return true;
+        }
+
+        return false;
+    }
+
+    private float calculateTargetEyeHeightWithGravity(float targetBodyHeight) {
+        float height = calculateTargetEyeHeight();
+
+        if (gravity.getGravitationConstant() < 0 && gravity.player.getOwner().isSneaking()) {
+            height += 0.2F;
+        }
+
+        if (gravity.getGravitationConstant() < 0) {
+            height = targetBodyHeight - height;
+        }
+
+        return height;
+    }
+
+    private float calculateTargetEyeHeight() {
+        if (gravity.player.hasEffect()) {
+            MagicEffect effect = gravity.player.getEffect();
+            if (!effect.isDead() && effect instanceof HeightPredicate) {
+                float val = ((HeightPredicate)effect).getTargetEyeHeight(gravity.player);
+                if (val > 0) {
+                    return val;
+                }
+            }
+        }
+
+        if (gravity.isFlying && gravity.isRainboom()) {
+            return 0.5F;
+        }
+
+        return defaultEyeHeight;
+    }
+
+    private float calculateTargetBodyHeight() {
+        if (gravity.player.hasEffect()) {
+            MagicEffect effect = gravity.player.getEffect();
+            if (!effect.isDead() && effect instanceof HeightPredicate) {
+                float val = ((HeightPredicate)effect).getTargetBodyHeight(gravity.player);
+                if (val > 0) {
+                    return val;
+                }
+            }
+        }
+
+        if (gravity.isFlying && gravity.isRainboom()) {
+            return defaultBodyHeight / 2;
+        }
+
+        return defaultBodyHeight;
+    }
+
+}

src/main/java/com/minelittlepony/unicopia/mixin/CriterionsRegistry.java

@@ -8,7 +8,7 @@ import net.minecraft.advancement.criterion.Criterions;
 
 @Mixin(Criterions.class)
 public interface CriterionsRegistry {
-    @Invoker
+    @Invoker("register")
     static <T extends Criterion<?>> T register(T object) {
         throw new NullPointerException("mixin y u fail");
     }

src/main/java/com/minelittlepony/unicopia/mixin/MixinEntity.java

@@ -1,12 +0,0 @@
-package com.minelittlepony.unicopia.mixin;
-
-import org.spongepowered.asm.mixin.Mixin;
-import org.spongepowered.asm.mixin.gen.Accessor;
-
-import net.minecraft.entity.Entity;
-
-@Mixin(Entity.class)
-public interface MixinEntity {
-    @Accessor("setSize")
-    void setSize(float width, float height);
-}

src/main/java/com/minelittlepony/unicopia/mixin/MixinFarmlandBlock.java

@@ -3,6 +3,7 @@ package com.minelittlepony.unicopia.mixin;
 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.unicopia.ducks.Farmland;
 
@@ -19,10 +20,11 @@ abstract class MixinFarmlandBlock extends Block {
             method = "setToDirt(Lnet/minecraft/block/BlockState;Lnet/minecraft/world/World;Lnet/minecraft/util/math/BlockPos;)V",
             at = @At("HEAD"),
             cancellable = true)
-    public static void setToDirt(BlockState state, World world, BlockPos pos) {
+    private static void setToDirt(BlockState state, World world, BlockPos pos, CallbackInfo info) {
         if (state.getBlock() instanceof Farmland) {
             BlockState dirtState = ((Farmland)state.getBlock()).getDirtState(state, world, pos);
             world.setBlockState(pos, pushEntitiesUpBeforeBlockChange(state, dirtState, world, pos));
+            info.cancel();
         }
     }
 }

src/main/java/com/minelittlepony/unicopia/mixin/MixinHoeItem.java

@@ -1,6 +1,9 @@
 package com.minelittlepony.unicopia.mixin;
 
 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.CallbackInfoReturnable;
 
 import com.minelittlepony.unicopia.util.HoeUtil;
 
@@ -13,19 +16,15 @@ import net.minecraft.util.ActionResult;
 @Mixin(HoeItem.class)
 abstract class MixinHoeItem extends ToolItem {
     MixinHoeItem() {super(null, null);}
-
+    @Inject(method = "useOnBlock(Lnet/minecraft/item/ItemUsageContext;)Lnet/minecraft/util/ActionResult;",
-    @Override
+            at = @At("HEAD"),
-    public ActionResult useOnBlock(ItemUsageContext context) {
+            cancellable = true)
-
+    private void onUseOnBlock(ItemUsageContext context, CallbackInfoReturnable<ActionResult> info) {
         BlockState state = context.getWorld().getBlockState(context.getBlockPos());
         if (state.getBlock() instanceof HoeUtil.Tillable) {
             if (!((HoeUtil.Tillable)state.getBlock()).canTill(context)) {
-                return ActionResult.PASS;
+                info.setReturnValue(ActionResult.PASS);
             }
         }
-
-        return null;
-
     }
-
 }

src/main/java/com/minelittlepony/unicopia/mixin/MixinItemEntity.java

@@ -13,7 +13,7 @@ import net.minecraft.entity.Entity;
 import net.minecraft.entity.ItemEntity;
 
 @Mixin(ItemEntity.class)
-public abstract class MixinItemEntity extends Entity implements IItemEntity {
+abstract class MixinItemEntity extends Entity implements IItemEntity {
 
     private final ItemEntityCapabilities caster = create();
 

src/main/java/com/minelittlepony/unicopia/mixin/MixinLivingEntity.java

@@ -14,7 +14,7 @@ import net.minecraft.entity.Entity;
 import net.minecraft.entity.LivingEntity;
 
 @Mixin(LivingEntity.class)
-public abstract class MixinLivingEntity extends Entity implements PonyContainer<Ponylike> {
+abstract class MixinLivingEntity extends Entity implements PonyContainer<Ponylike> {
 
     private final Ponylike caster = create();
 
@@ -30,15 +30,15 @@ public abstract class MixinLivingEntity extends Entity implements PonyContainer<
         return caster;
     }
 
-    @Inject(method = "canSee(Lnet/minecraft/entity/Entity)Z", at = @At("HEAD"))
+    @Inject(method = "canSee(Lnet/minecraft/entity/Entity;)Z", at = @At("HEAD"))
     private void onCanSee(Entity other, CallbackInfoReturnable<Boolean> info) {
         if (caster.isInvisible()) {
             info.setReturnValue(false);
         }
     }
 
-    @Inject(method = "method_6040()V", at = @At("HEAD"))
+    @Inject(method = "tickActiveItemStack()V", at = @At("HEAD"))
-    protected void onFinishUsing(CallbackInfo info) {
+    private void onFinishUsing(CallbackInfo info) {
         LivingEntity self = (LivingEntity)(Object)this;
 
         if (!self.getActiveItem().isEmpty() && self.isUsingItem()) {
@@ -63,7 +63,7 @@ public abstract class MixinLivingEntity extends Entity implements PonyContainer<
         caster.onUpdate();
     }
 
-    @Inject(method = "<clinit>()V", at = @At("RETURN"))
+    @Inject(method = "<clinit>()V", at = @At("RETURN"), remap = false)
     private static void clinit(CallbackInfo info) {
         LivingEntityCapabilities.boostrap();
     }

src/main/java/com/minelittlepony/unicopia/mixin/MixinPlayerEntity.java

@@ -3,7 +3,7 @@ package com.minelittlepony.unicopia.mixin;
 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.ModifyArg;
+import org.spongepowered.asm.mixin.injection.ModifyVariable;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
 
@@ -24,7 +24,7 @@ import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.GameMode;
 
 @Mixin(PlayerEntity.class)
-public abstract class MixinPlayerEntity extends LivingEntity implements PonyContainer<Pony> {
+abstract class MixinPlayerEntity extends LivingEntity implements PonyContainer<Pony> {
     private MixinPlayerEntity() { super(null, null); }
 
     @Override
@@ -32,9 +32,10 @@ public abstract class MixinPlayerEntity extends LivingEntity implements PonyCont
         return new PlayerImpl((PlayerEntity)(Object)this);
     }
 
-    @ModifyArg(method = "Lnet/minecraft/entity/LivingEntity;handleFallDamage(FF)V",
+    @ModifyVariable(method = "handleFallDamage(FF)Z",
             at = @At("HEAD"),
-            index = 0)
+            ordinal = 0,
+            argsOnly = true)
     private float onHandleFallDamage(float distance) {
         return get().onImpact(distance);
     }
@@ -68,9 +69,13 @@ public abstract class MixinPlayerEntity extends LivingEntity implements PonyCont
             at = @At("RETURN"),
             cancellable = true)
     private void onGetActiveEyeHeight(EntityPose pose, EntityDimensions dimensions, CallbackInfoReturnable<Float> info) {
-        float h = get().getGravity().getEyeHeight();
+        info.setReturnValue(get().getGravity().getDimensions().getActiveEyeHeight(info.getReturnValue()));
-        if (h != 0) {
+    }
-            info.setReturnValue(h);
+
-        }
+    @Inject(method = "getDimensions(Lnet/minecraft/entity/EntityPose;)Lnet/minecraft/entity/EntityDimensions;",
+            at = @At("RETURN"),
+            cancellable = true)
+    public void onGetDimensions(EntityPose pose, CallbackInfoReturnable<EntityDimensions> info) {
+        info.setReturnValue(get().getGravity().getDimensions().getDimensions(pose, info.getReturnValue()));
     }
 }

src/main/java/com/minelittlepony/unicopia/mixin/MixinProjectileEntity.java

@@ -13,9 +13,8 @@ import net.minecraft.entity.projectile.ProjectileEntity;
 import net.minecraft.util.hit.EntityHitResult;
 
 @Mixin(ProjectileEntity.class)
-public abstract class MixinProjectileEntity extends Entity implements Projectile {
+abstract class MixinProjectileEntity extends Entity implements Projectile {
-
+    private MixinProjectileEntity() { super(null, null); }
-    public MixinProjectileEntity() { super(null, null); }
 
     @Inject(method = "onEntityHit(Lnet/minecraft/util/hit/EntityHitResult;)V",
             at = @At("HEAD"),

src/main/java/com/minelittlepony/unicopia/mixin/client/MixinCamera.java

@@ -1,34 +1,59 @@
 package com.minelittlepony.unicopia.mixin.client;
 
 import org.spongepowered.asm.mixin.Mixin;
-import org.spongepowered.asm.mixin.Shadow;
 import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.At.Shift;
 import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.ModifyVariable;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 
 import com.minelittlepony.unicopia.entity.player.Pony;
-import com.minelittlepony.unicopia.entity.player.PlayerCamera;
-
 import net.minecraft.client.MinecraftClient;
 import net.minecraft.client.render.Camera;
+import net.minecraft.client.util.math.Vector3f;
 import net.minecraft.entity.player.PlayerEntity;
 
 @Mixin(Camera.class)
 abstract class MixinCamera {
-    @Shadow
+    @ModifyVariable(method = "setRotation(FF)V",
-    private float pitch;
+            at = @At("HEAD"),
-    @Shadow
+            ordinal = 0,
-    private float yaw;
+            argsOnly = true)
-
+    private float modifyYaw(float yaw) {
-    @Inject(method = "updateRotation()V", at = @At("HEAD"))
-    private void updateRotation() {
         PlayerEntity player = MinecraftClient.getInstance().player;
 
-        if (player != null) {
+        if (player != null && MinecraftClient.getInstance().cameraEntity == player) {
-            PlayerCamera view = Pony.of(player).getCamera();
+            return Pony.of(player).getCamera().calculateYaw(yaw);
+        }
 
-            //event.setRoll(view.calculateRoll());
+        return yaw;
-            pitch = view.calculatePitch(pitch);
+    }
-            yaw = view.calculateYaw(yaw);
+
+    @ModifyVariable(method = "setRotation(FF)V",
+            at = @At("HEAD"),
+            ordinal = 1,
+            argsOnly = true)
+    private float modifyPitch(float pitch) {
+        PlayerEntity player = MinecraftClient.getInstance().player;
+
+        if (player != null && MinecraftClient.getInstance().cameraEntity == player) {
+            return Pony.of(player).getCamera().calculatePitch(pitch);
+        }
+
+        return pitch;
+    }
+
+    @Inject(method = "setRotation(FF)V",
+            at = @At(value = "INVOKE",
+                target = "Lnet/minecraft/util/math/Quaternion;set(FFFF)V",
+                shift = Shift.AFTER)
+    )
+    private void onSetRotation(float yaw, float pitch, CallbackInfo info) {
+        PlayerEntity player = MinecraftClient.getInstance().player;
+
+        if (player != null && MinecraftClient.getInstance().cameraEntity == player) {
+            float roll = Pony.of(player).getCamera().calculateRoll();
+            ((Camera)(Object)this).getRotation().hamiltonProduct(Vector3f.POSITIVE_Z.getDegreesQuaternion(roll));
         }
     }
 }

src/main/java/com/minelittlepony/unicopia/mixin/client/MixinEntityRenderDispatcher.java

@@ -15,7 +15,10 @@ import net.minecraft.entity.player.PlayerEntity;
 
 @Mixin(EntityRenderDispatcher.class)
 abstract class MixinEntityRenderDispatcher {
-    @Inject(method = "render(Lnet/minecraft/entity/Entity;DDDFFLnet/minecraft/client/util/math/MatrixStack;Lnet/minecraft/client/render/VertexConsumerProvider;I)V", at = @At("HEAD"))
+
+    private static final String RENDER = "render(Lnet/minecraft/entity/Entity;DDDFFLnet/minecraft/client/util/math/MatrixStack;Lnet/minecraft/client/render/VertexConsumerProvider;I)V";
+
+    @Inject(method = RENDER, at = @At("HEAD"))
     private <E extends Entity> void beforeRender(E entity, double x, double y, double z, float yaw, float tickDelta, MatrixStack matrices, VertexConsumerProvider vertexConsumers, int light, CallbackInfo info) {
         matrices.push();
 
@@ -46,7 +49,7 @@ abstract class MixinEntityRenderDispatcher {
         }
     }
 
-    @Inject(method = "render(Lnet/minecraft/entity/Entity;DDDFFLnet/minecraft/client/util/math/MatrixStack;Lnet/minecraft/client/render/VertexConsumerProvider;I)V", at = @At("HEAD"))
+    @Inject(method = RENDER, at = @At("HEAD"))
     private <E extends Entity> void afterRender(E entity, double x, double y, double z, float yaw, float tickDelta, MatrixStack matrices, VertexConsumerProvider vertexConsumers, int light, CallbackInfo info) {
         matrices.pop();
 

src/main/java/com/minelittlepony/unicopia/mixin/client/MixinKeyboardInput.java

@@ -13,8 +13,8 @@ import net.minecraft.client.input.KeyboardInput;
 
 @Mixin(KeyboardInput.class)
 abstract class MixinKeyboardInput extends Input {
-    @Inject(method = "tick(ZZ)V", at = @At("RETURN"))
+    @Inject(method = "tick(Z)V", at = @At("RETURN"))
-    private void onTick(boolean one, boolean two, CallbackInfo info) {
+    private void onTick(boolean strafe, CallbackInfo info) {
         Pony player = Pony.of(MinecraftClient.getInstance().player);
 
         if (player.getGravity().getGravitationConstant() < 0) {

src/main/java/com/minelittlepony/unicopia/mixin/client/MixinMinecraftClient.java

@@ -16,10 +16,11 @@ import net.minecraft.util.Hand;
 import net.minecraft.util.hit.EntityHitResult;
 
 @Mixin(MinecraftClient.class)
-public class MixinMinecraftClient {
+abstract class MixinMinecraftClient {
-    @Redirect(method = "doItemPick()V", at = @At(
+    @Redirect(method = "doItemPick()V",
-                    value = "INVOKE",
+            at = @At(value = "INVOKE",
-                    target = "Lnet/minecraft/item/SpawnEggItem;forEntity(Lnet/minecraft/entity/EntityType;)Lnet/minecraft/item/SpawnEggItem;"))
+                    target = "Lnet/minecraft/item/SpawnEggItem;forEntity(Lnet/minecraft/entity/EntityType;)Lnet/minecraft/item/SpawnEggItem;")
+    )
     private SpawnEggItem redirectSpawnEggForEntity(EntityType<?> type) {
 
         MinecraftClient self = MinecraftClient.getInstance();

src/main/java/com/minelittlepony/unicopia/mixin/client/MixinMouse.java

@@ -1,6 +1,5 @@
 package com.minelittlepony.unicopia.mixin.client;
 
-import org.spongepowered.asm.mixin.Final;
 import org.spongepowered.asm.mixin.Mixin;
 import org.spongepowered.asm.mixin.Shadow;
 import org.spongepowered.asm.mixin.injection.At;
@@ -14,8 +13,6 @@ import net.minecraft.client.Mouse;
 
 @Mixin(Mouse.class)
 abstract class MixinMouse {
-    @Shadow
-    private @Final MinecraftClient client;
     @Shadow
     private double cursorDeltaX;
     @Shadow
@@ -23,7 +20,8 @@ abstract class MixinMouse {
 
     @Inject(method = "updateMouse()V", at = @At("HEAD"))
     private void onUpdateMouse(CallbackInfo info) {
-        if (Pony.of(client.player).getGravity().getGravitationConstant() < 0) {
+        Pony player = Pony.of(MinecraftClient.getInstance().player);
+        if (player != null&& player.getGravity().getGravitationConstant() < 0) {
             cursorDeltaX = -cursorDeltaX;
             cursorDeltaY = -cursorDeltaY;
         }

src/main/resources/unicopia.mixin.json

@@ -4,20 +4,23 @@
   "package": "com.minelittlepony.unicopia.mixin",
   "refmap": "unicopia.client.mixin.refmap.json",
   "compatibilityLevel": "JAVA_8",
-  "main": [
+  "mixins": [
-  	"MixinEntity",
+    "CriterionsRegistry",
-  	"MixinFarmlandBlock",
+    "MixinFarmlandBlock",
-  	"MixinHoeItem",
+    "MixinHoeItem",
-  	"MixinItemEntity",
+    "MixinItemEntity",
-  	"MixinPlayerEntity",
+    "MixinLivingEntity",
-  	"MixinProjectileEntity",
+    "MixinPlayerEntity",
-  	"Walker"
+    "MixinProjectileEntity",
+    "Walker"
   ],
   "client": [
+    "client.DefaultTexturesRegistry",
     "client.MixinCamera",
     "client.MixinEntityRenderDispatcher",
     "client.MixinGameRenderer",
     "client.MixinKeyboardInput",
+    "client.MixinMinecraftClient",
     "client.MixinMouse"
   ],
   "injectors": {