From b7873ef58825993f7b820ec78842d0e5bbd7a8a5 Mon Sep 17 00:00:00 2001
From: Paul Lemire <paul.lemire@kdab.com>
Date: Thu, 7 Nov 2019 08:26:57 +0100
Subject: QSortPolicy: add Uniform sorting mode

We used to perform uniform minization between adjacent render commands all the time.
Since this can yield to a higher CPU usages (but more efficient rendering submission),
we now make this step optional.

[ChangeLog] QSortPolicy add Uniform mode (to control whether uniform minization
should be performed)

Change-Id: I5c0e0dba22400a9884ee1d75426fd76b073fdcb5
Reviewed-by: Sean Harmer <sean.harmer@kdab.com>
---
 src/render/framegraph/qsortpolicy.cpp               | 7 +++++--
 src/render/framegraph/qsortpolicy.h                 | 1 +
 src/render/renderers/opengl/renderer/renderview.cpp | 8 ++++++++
 tests/auto/render/renderviews/tst_renderviews.cpp   | 1 +
 4 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/src/render/framegraph/qsortpolicy.cpp b/src/render/framegraph/qsortpolicy.cpp
index a24dd5eae..5c04025b0 100644
--- a/src/render/framegraph/qsortpolicy.cpp
+++ b/src/render/framegraph/qsortpolicy.cpp
@@ -98,12 +98,14 @@ QSortPolicyPrivate::QSortPolicyPrivate()
     projection of the camera-to-object-center vector onto the camera's view
     vector.
 
-    \value Material sort the objects based on their material value
+    \value Material sort the objects based on their material (shader) value.
 
     \value FrontToBack sort the objects from front to back. The opposite of
     BackToFront.
 
     \value [since 5.14] Texture sort the objects to minimize texture changes.
+
+    \value [since 5.15] Uniform sort the objects to minimize uniform changes.
 */
 
 /*!
@@ -123,10 +125,11 @@ QSortPolicyPrivate::QSortPolicyPrivate()
         order. More accurately, the sorting key is the z component of the
         projection of the camera-to-object-center vector onto the camera's view
         vector.
-    \li Material - sort the objects based on their material value
+    \li Material - sort the objects based on their material (shader) value.
     \li FrontToBack - sort the objects from front to back. The opposite of
         BackToFront.
     \li [since 5.14] Texture - sort the objects to minimize texture changes.
+    \li [since 5.15] Uniform - sort the objects to minimize uniform changes.
     \endlist
 */
 
diff --git a/src/render/framegraph/qsortpolicy.h b/src/render/framegraph/qsortpolicy.h
index a302caa8b..f5ea988e8 100644
--- a/src/render/framegraph/qsortpolicy.h
+++ b/src/render/framegraph/qsortpolicy.h
@@ -62,6 +62,7 @@ public:
         Material = (1 << 2),
         FrontToBack = (1 << 3),
         Texture = (1 << 4),
+        Uniform = (1 << 5)
     };
     Q_ENUM(SortType) // LCOV_EXCL_LINE
 
diff --git a/src/render/renderers/opengl/renderer/renderview.cpp b/src/render/renderers/opengl/renderer/renderview.cpp
index c00a92629..60ebc2193 100644
--- a/src/render/renderers/opengl/renderer/renderview.cpp
+++ b/src/render/renderers/opengl/renderer/renderview.cpp
@@ -467,6 +467,8 @@ int findSubRange(const QVector<RenderCommand> &commands,
         return advanceUntilNonAdjacent(commands, begin, end, AdjacentSubRangeFinder<QSortPolicy::FrontToBack>::adjacentSubRange);
     case QSortPolicy::Texture:
         return advanceUntilNonAdjacent(commands, begin, end, AdjacentSubRangeFinder<QSortPolicy::Texture>::adjacentSubRange);
+    case QSortPolicy::Uniform:
+        return end;
     default:
         Q_UNREACHABLE();
         return end;
@@ -513,6 +515,8 @@ void sortCommandRange(QVector<RenderCommand> &commands, int begin, const int end
     case QSortPolicy::Texture:
         SubRangeSorter<QSortPolicy::Texture>::sortSubRange(commands.begin() + begin, commands.begin() + end);
         break;
+    case QSortPolicy::Uniform:
+        break;
     default:
         Q_UNREACHABLE();
     }
@@ -536,6 +540,10 @@ void RenderView::sort()
     // For RenderCommand with the same shader
     // We compute the adjacent change cost
 
+     // Only perform uniform minimization if we explicitly asked for it
+     if (!m_data.m_sortingTypes.contains(QSortPolicy::Uniform))
+        return;
+
     // Minimize uniform changes
     int i = 0;
     const int commandSize = m_commands.size();
diff --git a/tests/auto/render/renderviews/tst_renderviews.cpp b/tests/auto/render/renderviews/tst_renderviews.cpp
index 1558b68c9..086ff0220 100644
--- a/tests/auto/render/renderviews/tst_renderviews.cpp
+++ b/tests/auto/render/renderviews/tst_renderviews.cpp
@@ -253,6 +253,7 @@ private Q_SLOTS:
 
         // WHEN
         renderView.setCommands(rawCommands);
+        renderView.addSortType((QVector<QSortPolicy::SortType>() << QSortPolicy::Uniform));
         renderView.sort();
 
         // THEN
-- 
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