From f3ab5c3b9ba1e91cb7fddd0e92a9cbd6c4bdccfd Mon Sep 17 00:00:00 2001
From: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
Date: Wed, 10 Feb 2021 09:29:24 +0100
Subject: [PATCH] WIP: Attempt at improving batch overlap detection

The current approach invalidates all batches between two render orders
that change. So if you have a scene with an animating alpha batch
at the beginning and end, then all alpha batches will be reuploaded
every frame.
---
 .../scenegraph/coreapi/qsgbatchrenderer.cpp   | 28 +++++++++++++------
 .../scenegraph/coreapi/qsgbatchrenderer_p.h   |  3 +-
 2 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp b/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
index c34327bb41..9f89bec4c6 100644
--- a/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
+++ b/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
@@ -978,8 +978,6 @@ Renderer::Renderer(QSGDefaultRenderContext *ctx)
     , m_tmpOpaqueElements(16)
     , m_rebuild(FullRebuild)
     , m_zRange(0)
-    , m_renderOrderRebuildLower(-1)
-    , m_renderOrderRebuildUpper(-1)
     , m_currentMaterial(nullptr)
     , m_currentShader(nullptr)
     , m_currentStencilValue(0)
@@ -1791,10 +1789,21 @@ void Renderer::invalidateBatchAndOverlappingRenderOrders(Batch *batch)
     Q_ASSERT(batch);
     Q_ASSERT(batch->first);
 
-    if (m_renderOrderRebuildLower < 0 || batch->first->order < m_renderOrderRebuildLower)
+    /*if (m_renderOrderRebuildLower < 0 || batch->first->order < m_renderOrderRebuildLower)
         m_renderOrderRebuildLower = batch->first->order;
     if (m_renderOrderRebuildUpper < 0 || batch->lastOrderInBatch > m_renderOrderRebuildUpper)
-        m_renderOrderRebuildUpper = batch->lastOrderInBatch;
+        m_renderOrderRebuildUpper = batch->lastOrderInBatch;*/
+
+    int start = batch->first->order;
+    int end = batch->lastOrderInBatch;
+    if (m_renderOrderRebuildRanges.size() < batch->lastOrderInBatch + 1) {
+        int start = std::min(start, m_renderOrderRebuildRanges.size());
+        m_renderOrderRebuildRanges.resize(batch->lastOrderInBatch + 1);
+    }
+
+    for (int i = start; i <= end; ++i)
+        m_renderOrderRebuildRanges[i] = (i >= batch->first->order && i <= batch->lastOrderInBatch);
+
 
     batch->invalidate();
 
@@ -1803,8 +1812,12 @@ void Renderer::invalidateBatchAndOverlappingRenderOrders(Batch *batch)
         if (b->first) {
             int bf = b->first->order;
             int bl = b->lastOrderInBatch;
-            if (bl > m_renderOrderRebuildLower && bf < m_renderOrderRebuildUpper)
-                b->invalidate();
+            for (int j = bf; j <= bl; ++j) {
+                if (j < m_renderOrderRebuildRanges.size() && m_renderOrderRebuildRanges.at(j)) {
+                    b->invalidate();
+                    break;
+                }
+            }
         }
     }
 
@@ -4346,8 +4359,7 @@ void Renderer::render()
     }
 
     m_rebuild = 0;
-    m_renderOrderRebuildLower = -1;
-    m_renderOrderRebuildUpper = -1;
+    m_renderOrderRebuildRanges.fill(false);
 
     if (m_visualizer->mode() != Visualizer::VisualizeNothing)
         m_visualizer->visualize();
diff --git a/src/quick/scenegraph/coreapi/qsgbatchrenderer_p.h b/src/quick/scenegraph/coreapi/qsgbatchrenderer_p.h
index 172d7c0e7f..08b906c313 100644
--- a/src/quick/scenegraph/coreapi/qsgbatchrenderer_p.h
+++ b/src/quick/scenegraph/coreapi/qsgbatchrenderer_p.h
@@ -871,8 +871,7 @@ private:
 
     uint m_rebuild;
     qreal m_zRange;
-    int m_renderOrderRebuildLower;
-    int m_renderOrderRebuildUpper;
+    QVector<bool> m_renderOrderRebuildRanges;
 
     GLuint m_bufferStrategy;
     int m_batchNodeThreshold;
-- 
2.21.0.windows.1