From c06627a230ea758c64ac70a9962a69c843fd0e08 Mon Sep 17 00:00:00 2001
From: Laszlo Agocs <laszlo.agocs@qt.io>
Date: Wed, 25 Sep 2019 15:14:05 +0200
Subject: [PATCH] rhi: metal: Eliminate redundant setCullMode and
 setFrontFaceWinding calls
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Task-number: QTBUG-78605
Change-Id: Icc3a9636055b5f45418da28cc05aa02e19370c02
Reviewed-by: Christian Strømme <christian.stromme@qt.io>
---
 src/gui/rhi/qrhimetal.mm    | 15 +++++++++++++--
 src/gui/rhi/qrhimetal_p_p.h |  5 +++++
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/gui/rhi/qrhimetal.mm b/src/gui/rhi/qrhimetal.mm
index bfd6944cdb6..d4043f00a5f 100644
--- a/src/gui/rhi/qrhimetal.mm
+++ b/src/gui/rhi/qrhimetal.mm
@@ -838,8 +838,15 @@ void QRhiMetal::setGraphicsPipeline(QRhiCommandBuffer *cb, QRhiGraphicsPipeline
 
         [cbD->d->currentRenderPassEncoder setRenderPipelineState: psD->d->ps];
         [cbD->d->currentRenderPassEncoder setDepthStencilState: psD->d->ds];
-        [cbD->d->currentRenderPassEncoder setCullMode: psD->d->cullMode];
-        [cbD->d->currentRenderPassEncoder setFrontFacingWinding: psD->d->winding];
+
+        if (cbD->currentCullMode == -1 || psD->d->cullMode != uint(cbD->currentCullMode)) {
+            [cbD->d->currentRenderPassEncoder setCullMode: psD->d->cullMode];
+            cbD->currentCullMode = int(psD->d->cullMode);
+        }
+        if (cbD->currentFrontFaceWinding == -1 || psD->d->winding != uint(cbD->currentFrontFaceWinding)) {
+            [cbD->d->currentRenderPassEncoder setFrontFacingWinding: psD->d->winding];
+            cbD->currentFrontFaceWinding = int(psD->d->winding);
+        }
     }
 
     psD->lastActiveFrameSlot = currentFrameSlot;
@@ -3450,6 +3457,10 @@ void QMetalCommandBuffer::resetPerPassCachedState()
     currentSrbGeneration = 0;
     currentResSlot = -1;
     currentIndexBuffer = nullptr;
+    currentIndexOffset = 0;
+    currentIndexFormat = QRhiCommandBuffer::IndexUInt16;
+    currentCullMode = -1;
+    currentFrontFaceWinding = -1;
 
     d->currentFirstVertexBinding = -1;
     d->currentVertexInputsBuffers.clear();
diff --git a/src/gui/rhi/qrhimetal_p_p.h b/src/gui/rhi/qrhimetal_p_p.h
index a08f56072a0..7fd7aba923e 100644
--- a/src/gui/rhi/qrhimetal_p_p.h
+++ b/src/gui/rhi/qrhimetal_p_p.h
@@ -271,8 +271,11 @@ struct QMetalCommandBuffer : public QRhiCommandBuffer
         ComputePass
     };
 
+    // per-pass (render or compute command encoder) persistent state
     PassType recordingPass;
     QRhiRenderTarget *currentTarget;
+
+    // per-pass (render or compute command encoder) volatile (cached) state
     QRhiGraphicsPipeline *currentGraphicsPipeline;
     QRhiComputePipeline *currentComputePipeline;
     uint currentPipelineGeneration;
@@ -283,6 +286,8 @@ struct QMetalCommandBuffer : public QRhiCommandBuffer
     QRhiBuffer *currentIndexBuffer;
     quint32 currentIndexOffset;
     QRhiCommandBuffer::IndexFormat currentIndexFormat;
+    int currentCullMode;
+    int currentFrontFaceWinding;
 
     const QRhiNativeHandles *nativeHandles();
     void resetState();