Layered turret top rendering

Source/CombatExtended/CombatExtended/Defs/TurretDrawExtension.cs

@@ -0,0 +1,26 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using UnityEngine;
+using Verse;
+
+namespace CombatExtended
+{
+    public class TurretDrawExtension : DefModExtension
+    {
+        public GraphicData TurretBottomGraphicData;
+
+        public GraphicData TurretTopGraphicData;
+
+        public List<TurretDrawExtension_BarrelOffsetPair> Barrels = new List<TurretDrawExtension_BarrelOffsetPair>();
+    }
+
+    public class TurretDrawExtension_BarrelOffsetPair
+    {
+        public Vector2 BarrelOffset;
+        public Material BarrelMaterial;
+        public GraphicData BarrelGraphicData;
+    }
+}

Source/CombatExtended/CombatExtended/Things/Building_TurretGunCE.cs

@@ -54,6 +54,10 @@ public class Building_TurretGunCE : Building_Turret
         private bool everSpawned = false;
         public GlobalTargetInfo globalTargetInfo = GlobalTargetInfo.Invalid;
 
+        public Material TurretTopBaseMaterial;
+        public Material TurretTopTopMaterial;
+        public List<TurretDrawExtension_BarrelOffsetPair> BarrelOffsetPairs = new List<TurretDrawExtension_BarrelOffsetPair>();
+
         #endregion
 
         #region Properties
@@ -193,6 +197,21 @@ public override void SpawnSetup(Map map, bool respawningAfterLoad)      //Add ma
                 }
             }
 
+            TurretDrawExtension turretDrawExtension = this.def.GetModExtension<TurretDrawExtension>();
+            if (turretDrawExtension != null)
+            {
+                TurretTopBaseMaterial = turretDrawExtension.TurretBottomGraphicData?.Graphic.MatSingle;
+                TurretTopTopMaterial = turretDrawExtension.TurretTopGraphicData?.Graphic.MatSingle;
+                if (turretDrawExtension.Barrels.Any())
+                {
+                    foreach (var barrel in turretDrawExtension.Barrels)
+                    {
+                        TurretDrawExtension_BarrelOffsetPair barrelCache = barrel;
+                        barrelCache.BarrelMaterial = barrel.BarrelGraphicData.Graphic.MatSingle;
+                        BarrelOffsetPairs.Add(barrelCache);
+                    }
+                }
+            }
             // if (CompAmmo == null || CompAmmo.Props == null || CompAmmo.Props.ammoSet == null || CompAmmo.Props.ammoSet.ammoTypes.NullOrEmpty())
             //     return;
 
@@ -587,10 +606,55 @@ public override void Draw()
             {
                 CE_Utility.Recoil(def.building.turretGunDef, AttackVerb, out drawOffset, out angleOffset, top.CurRotation, false);
             }
-            top.DrawTurret(drawOffset, angleOffset);
+            if (TurretTopBaseMaterial != null)
+            {
+                DrawTurretComponents(TurretTopBaseMaterial);
+            }
+            if (BarrelOffsetPairs.Any())
+            {
+                for (int i = 0; i < BarrelOffsetPairs.Count(); i++)
+                {
+                    if (i == AttackVerb.burstShotsLeft % BarrelOffsetPairs.Count())
+                    {
+                        DrawTurretComponentRecoiled(BarrelOffsetPairs[i].BarrelMaterial, BarrelOffsetPairs[i].BarrelOffset, drawOffset, angleOffset);
+                    }
+                    else
+                    {
+                        DrawTurretComponentRecoiled(BarrelOffsetPairs[i].BarrelMaterial, BarrelOffsetPairs[i].BarrelOffset, Vector3.zero, 0);
+                    }
+                }
+            }
+            else
+            {
+                top.DrawTurret(drawOffset, angleOffset);
+            }
+            if (TurretTopTopMaterial != null)
+            {
+                DrawTurretComponents(TurretTopTopMaterial, true);
+            }
             base.Draw();
         }
 
+        public void DrawTurretComponents(Material mat, bool above = false)
+        {
+            Vector3 v = new Vector3(def.building.turretTopOffset.x, 0f, def.building.turretTopOffset.y).RotatedBy(top.CurRotation);
+            float turretTopDrawSize = def.building.turretTopDrawSize;
+            float num = CurrentEffectiveVerb?.AimAngleOverride ?? top.CurRotation;
+            Matrix4x4 matrix = default(Matrix4x4);
+            matrix.SetTRS(DrawPos + (above ? 2 * Altitudes.AltIncVect : Altitudes.AltIncVect / 2) + v, (-90 + num).ToQuat(), new Vector3(turretTopDrawSize, 1f, turretTopDrawSize));
+            Graphics.DrawMesh(MeshPool.plane10, matrix, mat, 0);
+        }
+
+        public void DrawTurretComponentRecoiled(Material mat, Vector2 offset, Vector3 recoilDrawOffset, float recoilAngleOffset)
+        {
+            float turretTopDrawSize = def.building.turretTopDrawSize;
+            Vector3 v = recoilDrawOffset;
+            float num = CurrentEffectiveVerb?.AimAngleOverride ?? top.CurRotation;
+            Matrix4x4 matrix = default(Matrix4x4);
+            matrix.SetTRS(DrawPos + Altitudes.AltIncVect + v + new Vector3(offset.x, 0f, offset.y).RotatedBy(top.CurRotation), (-90 + num).ToQuat(), new Vector3(turretTopDrawSize, 1f, turretTopDrawSize));
+            Graphics.DrawMesh(MeshPool.plane10, matrix, mat, 0);
+        }
+
         public override void DrawExtraSelectionOverlays()           // Draw at range less than 1.42 tiles
         {
             float range = this.GunCompEq.PrimaryVerb.verbProps.range;