Halve default VSM softness. Scale VSM blurring to shadow resolution, so that low resolutions don't receive too much blur. Note: when using VSM, you should set all your large surfaces (such as floors or terrains) to cast shadows. Otherwise shadows will be unnaturally thin. The Urho builtin samples don't do this to avoid artifacts on mobiles where VSM can't be used, and the bias is tricky to get right.

Source/Urho3D/Graphics/Renderer.cpp

@@ -262,7 +262,7 @@ Renderer::Renderer(Context* context) :
     materialQuality_(QUALITY_HIGH),
     shadowMapSize_(1024),
     shadowQuality_(SHADOWQUALITY_PCF_16BIT),
-    shadowSoftness_(2.0f),
+    shadowSoftness_(1.0f),
     vsmShadowParams_(0.0000001f, 0.2f),
     maxShadowMaps_(1),
     minInstances_(2),
@@ -528,10 +528,10 @@ void Renderer::ReloadShaders()
     shadersDirty_ = true;
 }
 
-void Renderer::ApplyShadowMapFilter(View* view, Texture2D* shadowMap)
+void Renderer::ApplyShadowMapFilter(View* view, Texture2D* shadowMap, float blurScale)
 {
     if (shadowMapFilterInstance_ && shadowMapFilter_)
-        (shadowMapFilterInstance_->*shadowMapFilter_)(view, shadowMap);
+        (shadowMapFilterInstance_->*shadowMapFilter_)(view, shadowMap, blurScale);
 }
 
 Viewport* Renderer::GetViewport(unsigned index) const
@@ -1921,7 +1921,7 @@ void Renderer::HandleRenderUpdate(StringHash eventType, VariantMap& eventData)
 }
 
 
-void Renderer::BlurShadowMap(View* view, Texture2D* shadowMap)
+void Renderer::BlurShadowMap(View* view, Texture2D* shadowMap, float blurScale)
 {
     graphics_->SetBlendMode(BLEND_REPLACE);
     graphics_->SetDepthTest(CMP_ALWAYS);
@@ -1944,16 +1944,15 @@ void Renderer::BlurShadowMap(View* view, Texture2D* shadowMap)
 
     // Horizontal blur of the shadow map
     static const StringHash blurOffsetParam("BlurOffsets");
-    graphics_->SetShaderParameter(blurOffsetParam, Vector2(shadowSoftness_ / shadowMap->GetWidth(), 0.0f));
 
+    graphics_->SetShaderParameter(blurOffsetParam, Vector2(shadowSoftness_ * blurScale / shadowMap->GetWidth(), 0.0f));
     graphics_->SetTexture(TU_DIFFUSE, shadowMap);
     view->DrawFullscreenQuad(true);
 
     // Vertical blur
     graphics_->SetRenderTarget(0, shadowMap);
     graphics_->SetViewport(IntRect(0, 0, shadowMap->GetWidth(), shadowMap->GetHeight()));
-
-    graphics_->SetShaderParameter(blurOffsetParam, Vector2(0.0f, shadowSoftness_ / shadowMap->GetHeight()));
+    graphics_->SetShaderParameter(blurOffsetParam, Vector2(0.0f, shadowSoftness_ * blurScale / shadowMap->GetHeight()));
 
     graphics_->SetTexture(TU_DIFFUSE, tmpBuffer);
     view->DrawFullscreenQuad(true);

Source/Urho3D/Graphics/Renderer.h

@@ -173,7 +173,7 @@ class URHO3D_API Renderer : public Object
     URHO3D_OBJECT(Renderer, Object);
 
 public:
-    typedef void(Object::*ShadowMapFilter)(View* view, Texture2D* shadowMap);
+    typedef void(Object::*ShadowMapFilter)(View* view, Texture2D* shadowMap, float blurScale);
 
     /// Construct.
     Renderer(Context* context);
@@ -242,7 +242,7 @@ public:
     void ReloadShaders();
 
     /// Apply post processing filter to the shadow map. Called by View.
-    void ApplyShadowMapFilter(View* view, Texture2D* shadowMap);
+    void ApplyShadowMapFilter(View* view, Texture2D* shadowMap, float blurScale);
 
     /// Return number of backbuffer viewports.
     unsigned GetNumViewports() const { return viewports_.Size(); }
@@ -456,7 +456,7 @@ private:
     /// Handle render update event.
     void HandleRenderUpdate(StringHash eventType, VariantMap& eventData);
     /// Blur the shadow map.
-    void BlurShadowMap(View* view, Texture2D* shadowMap);
+    void BlurShadowMap(View* view, Texture2D* shadowMap, float blurScale);
 
     /// Graphics subsystem.
     WeakPtr<Graphics> graphics_;

Source/Urho3D/Graphics/View.cpp

@@ -2974,23 +2974,23 @@ void View::RenderShadowMap(const LightBatchQueue& queue)
     // Set shadow depth bias
     BiasParameters parameters = queue.light_->GetShadowBias();
 
-    // the shadow map is a depth stencil map
+    // The shadow map is a depth stencil texture
     if (shadowMap->GetUsage() == TEXTURE_DEPTHSTENCIL)
     {
         graphics_->SetColorWrite(false);
         graphics_->SetDepthStencil(shadowMap);
         graphics_->SetRenderTarget(0, shadowMap->GetRenderSurface()->GetLinkedRenderTarget());
-        // disable other render targets
+        // Disable other render targets
         for (unsigned i = 1; i < MAX_RENDERTARGETS; ++i)
             graphics_->SetRenderTarget(i, (RenderSurface*) 0);
         graphics_->SetViewport(IntRect(0, 0, shadowMap->GetWidth(), shadowMap->GetHeight()));
         graphics_->Clear(CLEAR_DEPTH);
     }
-    else // if the shadow map is a render texture
+    else // if the shadow map is a color rendertarget
     {
         graphics_->SetColorWrite(true);
         graphics_->SetRenderTarget(0, shadowMap);
-        // disable other render targets
+        // Disable other render targets
         for (unsigned i = 1; i < MAX_RENDERTARGETS; ++i)
             graphics_->SetRenderTarget(i, (RenderSurface*) 0);
         graphics_->SetDepthStencil(renderer_->GetDepthStencil(shadowMap->GetWidth(), shadowMap->GetHeight()));
@@ -3032,8 +3032,9 @@ void View::RenderShadowMap(const LightBatchQueue& queue)
         }
     }
 
-    renderer_->ApplyShadowMapFilter(this, shadowMap);
-
+    // Scale filter blur amount to shadow map viewport size so that different shadow map resolutions don't behave differently
+    float blurScale = queue.shadowSplits_[0].shadowViewport_.Width() / 1024.0f;
+    renderer_->ApplyShadowMapFilter(this, shadowMap, blurScale);
 
     // reset some parameters
     graphics_->SetColorWrite(true);