Improve gravity handling when applied to non-player entities

src/main/java/com/minelittlepony/unicopia/client/render/WorldRenderDelegate.java

@@ -2,7 +2,9 @@ package com.minelittlepony.unicopia.client.render;
 
 import javax.annotation.Nullable;
 
+import com.minelittlepony.unicopia.ability.magic.Caster;
 import com.minelittlepony.unicopia.ability.magic.spell.DisguiseSpell;
+import com.minelittlepony.unicopia.entity.Living;
 import com.minelittlepony.unicopia.entity.behaviour.Disguise;
 import com.minelittlepony.unicopia.entity.player.Pony;
 
@@ -30,7 +32,7 @@ import net.minecraft.util.math.Vec3d;
 public class WorldRenderDelegate {
     public static final WorldRenderDelegate INSTANCE = new WorldRenderDelegate();
 
-    public boolean onEntityRender(EntityRenderDispatcher dispatcher, Pony pony,
+    public boolean onEntityRender(EntityRenderDispatcher dispatcher, Living<?> pony,
             double x, double y, double z, float yaw,
             float tickDelta, MatrixStack matrices, VertexConsumerProvider vertexConsumers, int light) {
 
@@ -42,7 +44,7 @@ public class WorldRenderDelegate {
 
         float roll = negative ? 180 : 0;
 
-        roll = pony.getInterpolator().interpolate("g_roll", roll, 15);
+        roll = pony instanceof Pony ? ((Pony)pony).getInterpolator().interpolate("g_roll", roll, 15) : roll;
 
         if (negative) {
             matrices.translate(x, y, z);
@@ -55,9 +57,11 @@ public class WorldRenderDelegate {
             matrices.multiply(Vector3f.POSITIVE_Z.getDegreesQuaternion(roll));
         }
 
+        if (pony instanceof Caster<?>) {
+
             int fireTicks = pony.getMaster().doesRenderOnFire() ? 1 : 0;
 
-        return pony.getSpellOrEmpty(DisguiseSpell.class, true).map(effect -> {
+            return ((Caster<?>)pony).getSpellOrEmpty(DisguiseSpell.class, true).map(effect -> {
                 effect.update(pony, false);
 
                 Disguise ve = effect.getDisguise();
@@ -77,7 +81,10 @@ public class WorldRenderDelegate {
             }).orElse(false);
         }
 
-    public void afterEntityRender(Pony pony, MatrixStack matrices) {
+        return false;
+    }
+
+    public void afterEntityRender(Living<?> pony, MatrixStack matrices) {
 
         matrices.pop();
 

src/main/java/com/minelittlepony/unicopia/entity/ItemImpl.java

@@ -8,6 +8,7 @@ import com.minelittlepony.unicopia.item.enchantment.UEnchantments;
 import com.minelittlepony.unicopia.util.VecHelper;
 
 import net.minecraft.enchantment.EnchantmentHelper;
+import net.minecraft.entity.Entity;
 import net.minecraft.entity.ItemEntity;
 import net.minecraft.entity.MovementType;
 import net.minecraft.entity.data.DataTracker;
@@ -20,6 +21,7 @@ import net.minecraft.nbt.CompoundTag;
 import net.minecraft.particle.ParticleEffect;
 import net.minecraft.particle.ParticleTypes;
 import net.minecraft.util.ActionResult;
+import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.Vec3d;
 
 public class ItemImpl implements Equine<ItemEntity>, Owned<ItemEntity> {
@@ -90,6 +92,21 @@ public class ItemImpl implements Equine<ItemEntity>, Owned<ItemEntity> {
             }
         }
 
+        if (physics.isGravityNegative()) {
+            owner.setNoGravity(true);
+            owner.setOnGround(owner.verticalCollision);
+
+            float g = 0.98f;
+            if (owner.isOnGround()) {
+               g *= owner.world.getBlockState(owner.getBlockPos().up()).getBlock().getSlipperiness();
+            }
+
+            owner.setVelocity(owner.getVelocity()
+                    .add(0, physics.calcGravity(-0.04D), 0)
+                    .multiply(g, 1, g));
+
+        }
+
         return false;
     }
 

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

@@ -78,6 +78,7 @@ abstract class MixinPlayerEntity extends LivingEntity implements PonyContainer<P
     private void onDropItem(ItemStack itemStack_1, boolean scatter, boolean retainOwnership, CallbackInfoReturnable<ItemEntity> info) {
         PonyContainer.of(info.getReturnValue()).ifPresent(container -> {
             container.get().setSpecies(get().getSpecies());
+            container.get().getPhysics().setBaseGravityModifier(get().getPhysics().getGravityModifier());
         });
     }
 

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

@@ -6,13 +6,13 @@ import org.spongepowered.asm.mixin.injection.Inject;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 
 import com.minelittlepony.unicopia.client.render.WorldRenderDelegate;
-import com.minelittlepony.unicopia.entity.player.Pony;
+import com.minelittlepony.unicopia.entity.Equine;
 
 import net.minecraft.client.render.VertexConsumerProvider;
 import net.minecraft.client.render.entity.EntityRenderDispatcher;
 import net.minecraft.client.util.math.MatrixStack;
 import net.minecraft.entity.Entity;
-import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.entity.LivingEntity;
 
 @Mixin(EntityRenderDispatcher.class)
 abstract class MixinEntityRenderDispatcher {
@@ -21,21 +21,19 @@ abstract class MixinEntityRenderDispatcher {
 
     @Inject(method = RENDER, at = @At("HEAD"), cancellable = true)
     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) {
-        if (!(entity instanceof PlayerEntity)) {
+        if (!(entity instanceof LivingEntity)) {
             return;
         }
-
+        if (WorldRenderDelegate.INSTANCE.onEntityRender((EntityRenderDispatcher)(Object)this, Equine.of(entity), x, y, z, yaw, tickDelta, matrices, vertexConsumers, light)) {
-        if (WorldRenderDelegate.INSTANCE.onEntityRender((EntityRenderDispatcher)(Object)this, Pony.of((PlayerEntity)entity), x, y, z, yaw, tickDelta, matrices, vertexConsumers, light)) {
             info.cancel();
         }
     }
 
     @Inject(method = RENDER, at = @At("RETURN"))
     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) {
-        if (!(entity instanceof PlayerEntity)) {
+        if (!(entity instanceof LivingEntity)) {
             return;
         }
-
+        WorldRenderDelegate.INSTANCE.afterEntityRender(Equine.of(entity), matrices);
-        WorldRenderDelegate.INSTANCE.afterEntityRender(Pony.of((PlayerEntity)entity), matrices);
     }
 }