ZombieSky.cs

using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using Terraria;
using Terraria.Graphics.Effects;

namespace Tremor.ZombieEvent
{
	public class ZombieSky : CustomSky
	{
		private bool isActive;
		private float intensity;
		private int CalIndex = -1;

		public override void Update(GameTime gameTime)
		{
			if (isActive && intensity < 1f)
			{
				intensity += 0.01f;
			}
			else if (!isActive && intensity > 0f)
			{
				intensity -= 0.01f;
			}
		}
		
		private float GetIntensity()
		{
			if (UpdateCalIndex())
			{
				float x = 0f;
				if (CalIndex != -1)
				{
					x = Vector2.Distance(Main.player[Main.myPlayer].Center, Main.npc[CalIndex].Center);
				}
				return 1f - Utils.SmoothStep(3000f, 6000f, x);
			}
			return 0f;
		}
		
		public override Color OnTileColor(Color inColor)
		{
			float intensity = GetIntensity();
			return new Color(Vector4.Lerp(new Vector4(0.5f, 0.8f, 1f, 1f), inColor.ToVector4(), 1f - intensity));
		}

		private bool UpdateCalIndex()
		{
			bool CalType = ZWorld.ZInvasion;
			if (CalIndex >= 0 && Main.npc[CalIndex].active && CalType)
			{
				return true;
			}
			CalIndex = -1;
			for (int i = 0; i < Main.npc.Length; i++)
			{
				if (Main.npc[i].active && CalType)
				{
					CalIndex = i;
					break;
				}
			}
			//this.DoGIndex = DoGIndex;
			return CalIndex != -1;
		}

		public override void Draw(SpriteBatch spriteBatch, float minDepth, float maxDepth)
		{
			if (maxDepth >= 0 && minDepth < 0)
			{
				float intensity = GetIntensity();
				spriteBatch.Draw(Main.blackTileTexture, new Rectangle(0, 0, Main.screenWidth, Main.screenHeight), Color.Black * intensity);
			}
		}

		public override float GetCloudAlpha()
		{
			return 0f;
		}

		public override void Activate(Vector2 position, params object[] args)
		{
			isActive = true;
		}

		public override void Deactivate(params object[] args)
		{
			isActive = false;
		}

		public override void Reset()
		{
			isActive = false;
		}

		public override bool IsActive()
		{
			return isActive || intensity > 0f;
		}
	}
}