From 9dcdf10d1a762e2610aee4034833bdbbb8b81bec Mon Sep 17 00:00:00 2001
From: Jakub Melka <Jakub.Melka@seznam.cz>
Date: Sun, 14 Mar 2021 16:08:50 +0100
Subject: [PATCH] Bugfixing: Tensor product patch shading sampler

---
 Pdf4QtLib/sources/pdfpattern.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Pdf4QtLib/sources/pdfpattern.cpp b/Pdf4QtLib/sources/pdfpattern.cpp
index 3b84ea4..42ee4f7 100644
--- a/Pdf4QtLib/sources/pdfpattern.cpp
+++ b/Pdf4QtLib/sources/pdfpattern.cpp
@@ -3112,7 +3112,9 @@ public:
     virtual bool sample(const QPointF& devicePoint, PDFColorBuffer outputBuffer, int limit) const override
     {
         constexpr PDFReal epsilon = 0.001;
-        std::array initialSamples = { QPointF(0.5, 0.5) };
+        std::array initialSamples = { QPointF(0.5, 0.5), // Middle of the patch
+                                      QPointF(0.0, 0.0), QPointF(1.0, 0.0), QPointF(0.0, 1.0), QPointF(1.0, 1.0), // Four corners
+                                      QPointF(0.5, 0.0), QPointF(0.5, 1.0), QPointF(0.0, 0.5), QPointF(1.0, 0.5) }; // Middle point of edges
 
         for (const PDFTensorPatch& patch : m_patches)
         {