From fa0fb113293d9847da10089727504f9186c99e10 Mon Sep 17 00:00:00 2001
From: Brad Davis <bdavis@saintandreas.org>
Date: Tue, 25 Apr 2017 11:55:48 -0700
Subject: [PATCH] Remove uneeded memory to memory copy for mip transfers

---
 libraries/gpu-gl/src/gpu/gl/GLTexture.cpp | 42 ++++++++++-------------
 libraries/gpu-gl/src/gpu/gl/GLTexture.h   |  7 ++--
 2 files changed, 22 insertions(+), 27 deletions(-)

diff --git a/libraries/gpu-gl/src/gpu/gl/GLTexture.cpp b/libraries/gpu-gl/src/gpu/gl/GLTexture.cpp
index a6e6bf4fa3..27a31ca678 100644
--- a/libraries/gpu-gl/src/gpu/gl/GLTexture.cpp
+++ b/libraries/gpu-gl/src/gpu/gl/GLTexture.cpp
@@ -140,7 +140,7 @@ GLExternalTexture::~GLExternalTexture() {
         if (recycler) {
             backend->releaseExternalTexture(_id, recycler);
         } else {
-            qWarning() << "No recycler available for texture " << _id << " possible leak";
+            qCWarning(gpugllogging) << "No recycler available for texture " << _id << " possible leak";
         }
         const_cast<GLuint&>(_id) = 0;
     }
@@ -210,38 +210,32 @@ TransferJob::TransferJob(const GLTexture& parent, uint16_t sourceMip, uint16_t t
     format = texelFormat.format;
     internalFormat = texelFormat.internalFormat;
     type = texelFormat.type;
-    auto mipSize = _parent._gpuObject.getStoredMipFaceSize(sourceMip, face);
+    _transferSize = _parent._gpuObject.getStoredMipFaceSize(sourceMip, face);
 
-
-    if (0 == lines) {
-        _transferSize = mipSize;
-        _bufferingLambda = [=] {
-            auto mipData = _parent._gpuObject.accessStoredMipFace(sourceMip, face);
-            _buffer.resize(_transferSize);
-            memcpy(&_buffer[0], mipData->readData(), _transferSize);
-            _bufferingCompleted = true;
-        };
-
-    } else {
+    // If we're copying a subsection of the mip, do additional calculations to find the size and offset of the segment
+    if (0 != lines) {
         transferDimensions.y = lines;
         auto dimensions = _parent._gpuObject.evalMipDimensions(sourceMip);
-        auto bytesPerLine = (uint32_t)mipSize / dimensions.y;
-        auto sourceOffset = bytesPerLine * lineOffset;
+        auto bytesPerLine = (uint32_t)_transferSize / dimensions.y;
+        _transferOffset = bytesPerLine * lineOffset;
         _transferSize = bytesPerLine * lines;
-        _bufferingLambda = [=] {
-            auto mipData = _parent._gpuObject.accessStoredMipFace(sourceMip, face);
-            _buffer.resize(_transferSize);
-            memcpy(&_buffer[0], mipData->readData() + sourceOffset, _transferSize);
-            _bufferingCompleted = true;
-        };
     }
 
     Backend::updateTextureTransferPendingSize(0, _transferSize);
 
+    if (_transferSize > GLVariableAllocationSupport::MAX_TRANSFER_SIZE) {
+        qCWarning(gpugllogging) << "Transfer size of " << _transferSize << " exceeds theoretical maximum transfer size";
+    }
+
+    // Buffering can invoke disk IO, so it should be off of the main and render threads
+    _bufferingLambda = [=] {
+        _mipData = _parent._gpuObject.accessStoredMipFace(sourceMip, face)->createView(_transferSize, _transferOffset);
+        _bufferingCompleted = true;
+    };
+
     _transferLambda = [=] {
-        _parent.copyMipFaceLinesFromTexture(targetMip, face, transferDimensions, lineOffset, internalFormat, format, type, _buffer.size(), _buffer.data());
-        std::vector<uint8_t> emptyVector;
-        _buffer.swap(emptyVector);
+        _parent.copyMipFaceLinesFromTexture(targetMip, face, transferDimensions, lineOffset, internalFormat, format, type, _mipData->size(), _mipData->readData());
+        _mipData.reset();
     };
 }
 
diff --git a/libraries/gpu-gl/src/gpu/gl/GLTexture.h b/libraries/gpu-gl/src/gpu/gl/GLTexture.h
index 8b4b545b7d..b21ff53dd8 100644
--- a/libraries/gpu-gl/src/gpu/gl/GLTexture.h
+++ b/libraries/gpu-gl/src/gpu/gl/GLTexture.h
@@ -49,8 +49,10 @@ public:
         using VoidLambdaQueue = std::queue<VoidLambda>;
         using ThreadPointer = std::shared_ptr<std::thread>;
         const GLTexture& _parent;
-        // Holds the contents to transfer to the GPU in CPU memory
-        std::vector<uint8_t> _buffer;
+        Texture::PixelsPointer _mipData;
+        size_t _transferOffset { 0 };
+        size_t _transferSize { 0 };
+
         // Indicates if a transfer from backing storage to interal storage has started
         bool _bufferingStarted { false };
         bool _bufferingCompleted { false };
@@ -78,7 +80,6 @@ public:
 #endif
 
     private:
-        size_t _transferSize { 0 };
 #if THREADED_TEXTURE_BUFFERING
         void startBuffering();
 #endif