Name tags get redder the more an entity is hurt

src/main/java/net/arbee/addola/mixins/EntityRendererMixin.java

@@ -0,0 +1,28 @@
+package net.arbee.addola.mixins;
+
+import net.minecraft.client.render.VertexConsumerProvider;
+import net.minecraft.client.render.entity.EntityRenderer;
+import net.minecraft.client.util.math.MatrixStack;
+import net.minecraft.entity.Entity;
+import net.minecraft.entity.LivingEntity;
+import net.minecraft.text.Text;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.ModifyArgs;
+import org.spongepowered.asm.mixin.injection.invoke.arg.Args;
+
+import java.awt.*;
+
+@Mixin(EntityRenderer.class)
+public abstract class EntityRendererMixin<T extends Entity> {
+    @ModifyArgs(method = "renderLabelIfPresent", at = @At(value = "INVOKE", target = "Lnet/minecraft/client/font/TextRenderer;draw(Lnet/minecraft/text/Text;FFIZLnet/minecraft/util/math/Matrix4f;Lnet/minecraft/client/render/VertexConsumerProvider;ZII)I", ordinal = 1))
+    public void draw (Args args, T entity, Text text, MatrixStack matrices, VertexConsumerProvider vertexConsumers, int light) {
+        float healthPercent = ((LivingEntity)entity).getHealth() / ((LivingEntity)entity).getMaxHealth();
+        args.set(3, getCol(healthPercent));
+    }
+
+    public int getCol(float percent) {
+        int p = (int)(255 * percent);
+        return new Color(255, p, p).hashCode();
+    }
+}

src/main/java/net/arbee/addola/mixins/LivingEntityRendererMixin.java

@@ -0,0 +1,34 @@
+package net.arbee.addola.mixins;
+
+import net.minecraft.client.render.entity.EntityRenderDispatcher;
+import net.minecraft.client.render.entity.EntityRenderer;
+import net.minecraft.client.render.entity.LivingEntityRenderer;
+import net.minecraft.client.render.entity.PlayerModelPart;
+import net.minecraft.client.render.entity.feature.FeatureRendererContext;
+import net.minecraft.client.render.entity.model.EntityModel;
+import net.minecraft.client.util.math.MatrixStack;
+import net.minecraft.client.util.math.Vector3f;
+import net.minecraft.entity.LivingEntity;
+import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.util.Formatting;
+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;
+
+@Mixin(LivingEntityRenderer.class)
+public abstract class LivingEntityRendererMixin<T extends LivingEntity, M extends EntityModel<T>> extends EntityRenderer<T> implements FeatureRendererContext<T, M> {
+    protected LivingEntityRendererMixin(EntityRenderDispatcher dispatcher) {
+        super(dispatcher);
+    }
+
+    @Inject(method = "setupTransforms", at = @At(value = "TAIL"))
+    protected void setupTransforms(T entity, MatrixStack matrices, float animationProgress, float bodyYaw, float tickDelta, CallbackInfo ci) {
+        if (entity.hasCustomName() || entity instanceof PlayerEntity) {
+            String string = Formatting.strip(entity.getName().getString());
+            if ("guendahr".equals(string) && (!(entity instanceof PlayerEntity) || ((PlayerEntity)entity).isPartVisible(PlayerModelPart.CAPE))) {
+                matrices.multiply(Vector3f.POSITIVE_Y.getDegreesQuaternion(180.0F));
+            }
+        }
+    }
+}

src/main/resources/addola.mixins.json

@@ -8,6 +8,8 @@
     "BoatEntityAccess",
     "BoatEntityMixin",
     "BoatItemAccess",
+    "EntityRendererMixin",
+    "LivingEntityRendererMixin",
     "ServerWorldMixin",
     "VillagerMixin"
   ],