Fix #174: improve shadows in IVAs

-Not really sure why this happens, but unity's "soft" shadow mode really butchers the shadows inside IVAs.  So we change it to use "hard" mode instead, and tweak the bias numbers to make it look better
-also disable shadow casting on internal depth masks and any window renderers, so the sunlight comes through them

FreeIva/FreeIva.cs

@@ -104,6 +104,12 @@ public void Start()
 			Physics.IgnoreLayerCollision((int)Layers.Kerbals, (int)Layers.InternalSpace);
 			Physics.IgnoreLayerCollision((int)Layers.Kerbals, (int)Layers.Kerbals, false);
 
+			var ivaSun = InternalSpace.Instance.transform.Find("IVASun").GetComponent<IVASun>();
+			ivaSun.ivaLight.shadowBias = 0;
+			ivaSun.ivaLight.shadowNormalBias = 0;
+			ivaSun.ivaLight.shadows = LightShadows.Hard;
+
+
 			// prevent mouse clicks from hitting the kerbal collider or the internal shell
 			// Some of the shell colliders are a little too tight and block props
 			// This has a few downsides:

FreeIva/Gui/GuiManager.cs

@@ -96,6 +96,7 @@ public static void Gui()
 #if Experimental
 			PressureGui();
 #endif
+			ShadowsGui();
 			SeatGui();
 			PropGui();
 			MeshRendererGui();
@@ -111,6 +112,29 @@ public static void Gui()
 			//GUILayout.Label("Colliding: " + colliding);
 		}
 
+		private static bool showShadowGui = false;
+		private static void ShadowsGui()
+		{
+			if (GUILayout.Button((showShadowGui ? "Hide" : "Show") + " shadows configuration"))
+			{
+				showShadowGui = !showShadowGui;
+			}
+
+			if (!showShadowGui) return;
+
+			IVASun ivaSun = InternalSpace.Instance.transform.Find("IVASun").GetComponent<IVASun>();
+
+			float bias = ivaSun.ivaLight.shadowBias;
+			GuiUtils.slider("bias", ref bias, 0, 1);
+			ivaSun.ivaLight.shadowBias = bias;
+
+			float normalBias = ivaSun.ivaLight.shadowNormalBias;
+			GuiUtils.slider("normal bias", ref normalBias, 0, 1);
+			ivaSun.ivaLight.shadowNormalBias = normalBias;
+
+			ivaSun.ivaLight.shadows = (LightShadows)GuiUtils.radioButtons(Enum.GetNames(typeof(LightShadows)), (int)ivaSun.ivaLight.shadows);
+		}
+
 		private static bool showKerbalColliderGui = false;
 		private static void KerbalColliderGui()
 		{

FreeIva/InternalModules/InternalModuleFreeIva.cs

@@ -327,6 +327,8 @@ private void OnLoad_DepthMasks()
 				{
 					meshRenderer.sharedMaterial = Utils.GetDepthMaskCullingMaterial();
 					meshRenderer.gameObject.layer = (int)Layers.InternalSpace;
+					meshRenderer.shadowCastingMode = UnityEngine.Rendering.ShadowCastingMode.Off;
+					meshRenderer.receiveShadows = false;
 				}
 			}
 		}
@@ -391,6 +393,7 @@ private bool OnLoad_Windows(ConfigNode node)
 					{
 						hasWindows = true;
 						meshRenderer.material.renderQueue = WINDOW_RENDER_QUEUE;
+						meshRenderer.shadowCastingMode = UnityEngine.Rendering.ShadowCastingMode.Off;
 						Debug.Log($"[FreeIva] INTERNAL '{internalModel.internalName}' auto-detected window transform '{meshRenderer.transform.name}'");
 					}
 				}