Fix picking with primitive restart

Task-number: QTBUG-71919
Change-Id: If7923fab6c43f5d7139d1bbdceb73c17bf489099
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

4 files changed, 22 insertions, 2 deletions

diff --git a/src/render/backend/bufferutils_p.h b/src/render/backend/bufferutils_p.h
index 2bb35fac6..ea783df0d 100644
--- a/src/render/backend/bufferutils_p.h
+++ b/src/render/backend/bufferutils_p.h
@@ -74,6 +74,8 @@ struct BufferInfo
         , count(0)
         , byteStride(0)
         , byteOffset(0)
+        , restartEnabled(false)
+        , restartIndexValue(-1)
     {}
 
     QByteArray data;
@@ -82,6 +84,8 @@ struct BufferInfo
     uint count;
     uint byteStride;
     uint byteOffset;
+    bool restartEnabled;
+    int restartIndexValue;
 };
 
 
diff --git a/src/render/backend/segmentsvisitor.cpp b/src/render/backend/segmentsvisitor.cpp
index a3a5d059c..68deafb15 100644
--- a/src/render/backend/segmentsvisitor.cpp
+++ b/src/render/backend/segmentsvisitor.cpp
@@ -140,13 +140,18 @@ void traverseSegmentStripIndexed(Index *indices,
 
     uint ndx[2];
     Vector3D abc[2];
-    ndx[0] = indices[0];
+
+    startLinePrimitive:ndx[0] = indices[i];
     uint idx = ndx[0] * verticesStride;
     for (uint j = 0; j < maxVerticesDataSize; ++j)
         abc[0][j] = vertices[idx + j];
     while (i < indexInfo.count - 1) {
         ndx[1] = indices[i + 1];
         if (ndx[0] != ndx[1]) {
+            if (indexInfo.restartEnabled && indexInfo.restartIndexValue == static_cast<int>(ndx[1])) {
+                i += 2;
+                goto startLinePrimitive;
+            }
             idx = ndx[1] * verticesStride;
             for (uint j = 0; j < maxVerticesDataSize; ++j)
                 abc[1][j] = vertices[idx + j];
diff --git a/src/render/backend/trianglesvisitor.cpp b/src/render/backend/trianglesvisitor.cpp
index 87ba7bde9..a58f2d20b 100644
--- a/src/render/backend/trianglesvisitor.cpp
+++ b/src/render/backend/trianglesvisitor.cpp
@@ -153,6 +153,10 @@ void traverseTriangleStripIndexed(index *indices,
     uint ndx[3];
     Vector3D abc[3];
     while (i < indexInfo.count - 2) {
+        if (indexInfo.restartEnabled && indexInfo.restartIndexValue == static_cast<int>(indices[i + 2])) {
+            i += 3;
+            continue;
+        }
         bool degenerate = false;
         for (uint u = 0; u < 3; ++u) {
             ndx[u] = indices[i + u];
@@ -216,6 +220,11 @@ void traverseTriangleFanIndexed(index *indices,
     ndx[0] = indices[0];
     uint i = 1;
     while (i < indexInfo.count - 1) {
+        if (indexInfo.restartEnabled && indexInfo.restartIndexValue == static_cast<int>(indices[i + 1])) {
+            ndx[0] = indices[i + 2];
+            i += 3;
+            continue;
+        }
         for (uint u = 0; u < 2; ++u) {
             ndx[u + 1] = indices[i + u];
             uint idx = ndx[u + 1] * verticesStride;
@@ -224,7 +233,7 @@ void traverseTriangleFanIndexed(index *indices,
             }
         }
         visitor->visit(ndx[2], abc[2], ndx[1], abc[1], ndx[0], abc[0]);
-        i += 1;
+        ++i;
     }
 }
 
diff --git a/src/render/backend/visitorutils_p.h b/src/render/backend/visitorutils_p.h
index 6a5c7b4ff..14183e11b 100644
--- a/src/render/backend/visitorutils_p.h
+++ b/src/render/backend/visitorutils_p.h
@@ -149,6 +149,8 @@ void visitPrimitives(NodeManagers *manager, const GeometryRenderer *renderer, Vi
                 indexBufferInfo.byteOffset = indexAttribute->byteOffset();
                 indexBufferInfo.byteStride = indexAttribute->byteStride();
                 indexBufferInfo.count = indexAttribute->count();
+                indexBufferInfo.restartEnabled = renderer->primitiveRestartEnabled();
+                indexBufferInfo.restartIndexValue = renderer->restartIndexValue();
 
                 IndexExecutor executor;
                 executor.m_vertexBufferInfo = vertexBufferInfo;