MineLittlePony/src/main/java/com/minelittlepony/client/mixin/MixinClientPlayerEntity.java

package com.minelittlepony.client.mixin;

import com.minelittlepony.api.pony.IPony;
import com.minelittlepony.client.pony.Pony;
import com.minelittlepony.client.render.EquineRenderManager;

import net.minecraft.client.network.AbstractClientPlayerEntity;
import net.minecraft.client.network.ClientPlayerEntity;
import net.minecraft.entity.Entity;
import net.minecraft.entity.EntityDimensions;
import net.minecraft.entity.EntityPose;

import org.jetbrains.annotations.Nullable;
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 org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;

@Mixin(ClientPlayerEntity.class)
abstract class MixinClientPlayerEntity extends AbstractClientPlayerEntity implements EquineRenderManager.RegistrationHandler {
    public MixinClientPlayerEntity() { super(null, null); }

    @Nullable
    private IPony pony;

    @Inject(method = "startRiding(Lnet/minecraft/entity/Entity;Z)Z", at = @At("RETURN"))
    private void onStartRiding(Entity entity, boolean bl, CallbackInfoReturnable<Boolean> info) {
        calculateDimensions();
    }

    @Inject(method = "dismountVehicle()V", at = @At("RETURN"))
    private void onStopRiding(CallbackInfo info) {
        calculateDimensions();
    }

    @Override
    public boolean shouldUpdateRegistration(IPony pony) {
        if (this.pony != pony && (this.pony == null || this.pony.metadata().compareTo(pony.metadata()) != 0)) {
            this.pony = Pony.snapshot(pony);
            return true;
        }
        return false;
    }

    @Override
    public float getActiveEyeHeight(EntityPose pose, EntityDimensions dimensions) {
        float value = super.getActiveEyeHeight(pose, dimensions);

        IPony pony = IPony.getManager().getPony(this);

        if (!pony.race().isHuman()) {
            float factor = pony.metadata().getSize().getEyeHeightFactor();
            if (factor != 1) {
                value *= factor;

                if (hasVehicle()) {
                    value += getVehicle().getEyeHeight(getVehicle().getPose());
                    value -= getVehicle().getMountedHeightOffset();
                }

                return Math.max(value, 0.1F);
            }
        }

        return value;
    }
}