Write z data to the depth buffer.

OpenRA.Game/Game.cs

@@ -156,7 +156,7 @@ namespace OpenRA
 			using (new PerfTimer("NewWorld"))
 				OrderManager.World = new World(map, OrderManager, type);
 
-			worldRenderer = new WorldRenderer(OrderManager.World);
+			worldRenderer = new WorldRenderer(ModData, OrderManager.World);
 
 			using (new PerfTimer("LoadComplete"))
 				OrderManager.World.LoadComplete(worldRenderer);

OpenRA.Game/Graphics/IGraphicsDevice.cs

@@ -70,6 +70,7 @@ namespace OpenRA
 
 		void EnableDepthBuffer();
 		void DisableDepthBuffer();
+		void ClearDepthBuffer();
 
 		void SetBlendMode(BlendMode mode);
 

OpenRA.Game/Graphics/WorldRenderer.cs

@@ -34,8 +34,9 @@ namespace OpenRA.Graphics
 		readonly TerrainRenderer terrainRenderer;
 		readonly Lazy<DeveloperMode> devTrait;
 		readonly Func<string, PaletteReference> createPaletteReference;
+		readonly bool enableDepthBuffer;
 
-		internal WorldRenderer(World world)
+		internal WorldRenderer(ModData modData, World world)
 		{
 			World = world;
 			TileSize = World.Map.Grid.TileSize;
@@ -43,6 +44,9 @@ namespace OpenRA.Graphics
 
 			createPaletteReference = CreatePaletteReference;
 
+			var mapGrid = modData.Manifest.Get<MapGrid>();
+			enableDepthBuffer = mapGrid.EnableDepthBuffer;
+
 			foreach (var pal in world.TraitDict.ActorsWithTrait<ILoadsPalettes>())
 				pal.Trait.LoadPalettes(this);
 
@@ -133,18 +137,27 @@ namespace OpenRA.Graphics
 			var bounds = Viewport.GetScissorBounds(World.Type != WorldType.Editor);
 			Game.Renderer.EnableScissor(bounds);
 
+			if (enableDepthBuffer)
+				Game.Renderer.Device.EnableDepthBuffer();
+
 			terrainRenderer.Draw(this, Viewport);
 			Game.Renderer.Flush();
 
 			for (var i = 0; i < renderables.Count; i++)
 				renderables[i].Render(this);
 
+			if (enableDepthBuffer)
+				Game.Renderer.ClearDepthBuffer();
+
 			foreach (var a in World.ActorsWithTrait<IPostRender>())
 				if (a.Actor.IsInWorld && !a.Actor.Disposed)
 					a.Trait.RenderAfterWorld(this, a.Actor);
 
 			var renderShroud = World.RenderPlayer != null ? World.RenderPlayer.Shroud : null;
 
+			if (enableDepthBuffer)
+				Game.Renderer.ClearDepthBuffer();
+
 			foreach (var a in World.ActorsWithTrait<IRenderShroud>())
 				a.Trait.RenderShroud(this, renderShroud);
 
@@ -152,6 +165,9 @@ namespace OpenRA.Graphics
 				for (var i = 0; i < renderables.Count; i++)
 					renderables[i].RenderDebugGeometry(this);
 
+			if (enableDepthBuffer)
+				Game.Renderer.Device.DisableDepthBuffer();
+
 			Game.Renderer.DisableScissor();
 
 			var overlayRenderables = World.Selection.Actors.Where(a => !a.Disposed)
@@ -209,6 +225,12 @@ namespace OpenRA.Graphics
 			return new float2(TileSize.Width * pos.X / 1024f, TileSize.Height * (pos.Y - pos.Z) / 1024f);
 		}
 
+		public float3 Screen3DPosition(WPos pos)
+		{
+			var z = ZPosition(pos, 0) * TileSize.Height / 1024f;
+			return new float3(TileSize.Width * pos.X / 1024f, TileSize.Height * (pos.Y - pos.Z) / 1024f, z);
+		}
+
 		public int2 ScreenPxPosition(WPos pos)
 		{
 			// Round to nearest pixel

OpenRA.Game/Renderer.cs

@@ -255,6 +255,12 @@ namespace OpenRA
 			Device.DisableDepthBuffer();
 		}
 
+		public void ClearDepthBuffer()
+		{
+			Flush();
+			Device.ClearDepthBuffer();
+		}
+
 		public void GrabWindowMouseFocus()
 		{
 			Device.GrabWindowMouseFocus();

OpenRA.Platforms.Default/Sdl2GraphicsDevice.cs

@@ -213,7 +213,7 @@ namespace OpenRA.Platforms.Default
 			VerifyThreadAffinity();
 			OpenGL.glClearColor(0, 0, 0, 1);
 			OpenGL.CheckGLError();
-			OpenGL.glClear(OpenGL.GL_COLOR_BUFFER_BIT);
+			OpenGL.glClear(OpenGL.GL_COLOR_BUFFER_BIT | OpenGL.GL_DEPTH_BUFFER_BIT);
 			OpenGL.CheckGLError();
 		}
 
@@ -235,6 +235,13 @@ namespace OpenRA.Platforms.Default
 			OpenGL.CheckGLError();
 		}
 
+		public void ClearDepthBuffer()
+		{
+			VerifyThreadAffinity();
+			OpenGL.glClear(OpenGL.GL_DEPTH_BUFFER_BIT);
+			OpenGL.CheckGLError();
+		}
+
 		public void SetBlendMode(BlendMode mode)
 		{
 			VerifyThreadAffinity();

glsl/shp.frag

@@ -17,25 +17,20 @@ void main()
 	if (c.a == 0.0)
 		discard;
 
-	if (EnableDepthPreview && length(vDepthMask) > 0.0)
+	float depth = gl_FragCoord.z;
+	if (length(vDepthMask) > 0.0)
 	{
-		if (abs(DepthTextureScale) > 0.0)
-		{
-			// Preview vertex aware depth
-			float depth = gl_FragCoord.z + DepthTextureScale * dot(x, vDepthMask);
+		// Preview vertex aware depth
+		depth = depth + DepthTextureScale * dot(x, vDepthMask);
+	}
 
-			// Convert to window coords
-			depth = 0.5 * depth + 0.5;
+	// Convert to window coords
+	gl_FragDepth = 0.5 * depth + 0.5;
 
-			// Front of the depth buffer is at 0, but we want to render it as bright
-			gl_FragColor = vec4(vec3(1.0 - depth), 1.0);
-		}
-		else
-		{
-			// Preview boring sprite-only depth
-			float depth = dot(x, vDepthMask);
-			gl_FragColor = vec4(depth, depth, depth, 1.0);
-		}
+	if (EnableDepthPreview)
+	{
+		// Front of the depth buffer is at 0, but we want to render it as bright
+		gl_FragColor = vec4(vec3(1.0 - gl_FragDepth), 1.0);
 	}
 	else
 		gl_FragColor = c;