Implement two-pass rendering for transparent objects

If object has both opaque parts and transparent parts it will be rendered
incorrectly due to no z-buffering. Add two-pass method to render the
opaque and transparent parts separately.

- Add opaque pixel check to transparency check of images.
- Add alpha test rendering to default material shadows too.

Task-number: QT3DS-3515
Change-Id: I9700b8fb463df9143c5bb9cbe66c7570081ebf5c
Reviewed-by: Miikka Heikkinen <miikka.heikkinen@qt.io>
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>

1 files changed, 17 insertions, 4 deletions

diff --git a/src/runtimerender/resourcemanager/Qt3DSRenderBufferManager.cpp b/src/runtimerender/resourcemanager/Qt3DSRenderBufferManager.cpp
index eb23f3d..b140e85 100644
--- a/src/runtimerender/resourcemanager/Qt3DSRenderBufferManager.cpp
+++ b/src/runtimerender/resourcemanager/Qt3DSRenderBufferManager.cpp
@@ -154,11 +154,13 @@ struct SBufferManager : public IBufferManager
         return m_StrTable->RegisterStr(m_PathBuilder.c_str());
     }
 
-    void SetImageHasTransparency(CRegisteredString inImagePath, bool inHasTransparency) override
+    void SetImageHasTransparency(CRegisteredString inImagePath, bool inHasTransparency,
+                                 bool hasOpaque) override
     {
         pair<TImageMap::iterator, bool> theImage =
             m_ImageMap.insert(make_pair(inImagePath, SImageEntry()));
         theImage.first->second.m_TextureFlags.SetHasTransparency(inHasTransparency);
+        theImage.first->second.m_TextureFlags.setHasOpaquePixels(hasOpaque);
     }
 
     bool GetImageHasTransparency(CRegisteredString inSourcePath) const override
@@ -169,6 +171,14 @@ struct SBufferManager : public IBufferManager
         return false;
     }
 
+    bool GetImageHasOpaquePixels(CRegisteredString inSourcePath) const override
+    {
+        TImageMap::const_iterator theIter = m_ImageMap.find(inSourcePath);
+        if (theIter != m_ImageMap.end())
+            return theIter->second.m_TextureFlags.HasOpaquePixels();
+        return false;
+    }
+
     void SetImageTransparencyToFalseIfNotSet(CRegisteredString inSourcePath) override
     {
         pair<TImageMap::iterator, bool> theImage =
@@ -512,9 +522,12 @@ struct SBufferManager : public IBufferManager
             if (theDecompressedImage.data)
                 inLoadedImage.ReleaseDecompressedTexture(theDecompressedImage);
         }
-        if (wasInserted == true || inForceScanForTransparency)
-            theImage.first->second.m_TextureFlags.SetHasTransparency(
-                inLoadedImage.ScanForTransparency());
+        if (wasInserted || inForceScanForTransparency) {
+            auto &flags = theImage.first->second.m_TextureFlags;
+            bool alsoOpaquePixels = false;
+            flags.SetHasTransparency(inLoadedImage.ScanForTransparency(alsoOpaquePixels));
+            flags.setHasOpaquePixels(alsoOpaquePixels);
+        }
         theImage.first->second.m_Texture = theTexture;
         return theImage.first->second;
     }