flip horizontal UVs of cubemap render

Effects/HLSL/LinearDepthEffect.fx

@@ -25,6 +25,7 @@ VertexShaderOutput main_vs(VertexShaderInput input)
 {
     VertexShaderOutput output;
     output.Position = mul(input.Position, ModelViewProjection);
+    output.Position.x *= -1; // otherwise cube map render will be horizontally flipped
     output.PositionWorld = mul(input.Position, Model);
     return output;
 }

Renderer.cs

@@ -276,7 +276,7 @@ namespace Kav
             TextureCube skybox
         ) {
             GraphicsDevice.RasterizerState.CullMode = CullMode.CullClockwiseFace;
-            SkyboxEffect.Skybox = skybox;
+            SkyboxEffect.Skybox = PointShadowCubeMap;
 
             var view = camera.View;
             view.Translation = Vector3.Zero;