From 0b6e8f366cf88af6cfa401817a9f4b8e0995470f Mon Sep 17 00:00:00 2001
From: Par Winzell <zell@fb.com>
Date: Wed, 18 Oct 2017 19:26:27 -0700
Subject: [PATCH] Only ever create one BufferViewData per file.

It is not uncommon for multiple logical textures in an FBX to reference
the same filename. Each such filename should yield one buffer view only,
and all sharing textures should reference it.
---
 src/Raw2Gltf.cpp | 54 ++++++++++++++++++++++++++++++++++--------------
 1 file changed, 39 insertions(+), 15 deletions(-)

diff --git a/src/Raw2Gltf.cpp b/src/Raw2Gltf.cpp
index 2ea7465..4c9a87a 100644
--- a/src/Raw2Gltf.cpp
+++ b/src/Raw2Gltf.cpp
@@ -93,6 +93,35 @@ struct GLTFData
         return bufferView;
     }
 
+    std::shared_ptr<BufferViewData> AddBufferViewForFile(BufferData &buffer, const std::string &filename)
+    {
+        // see if we've already created a BufferViewData for this precise file
+        auto iter = filenameToBufferView.find(filename);
+        if (iter != filenameToBufferView.end()) {
+            return iter->second;
+        }
+
+        std::shared_ptr<BufferViewData> result;
+        std::ifstream file(filename, std::ios::binary | std::ios::ate);
+        if (file) {
+            std::streamsize size = file.tellg();
+            file.seekg(0, std::ios::beg);
+
+            std::vector<char> fileBuffer(size);
+            if (file.read(fileBuffer.data(), size)) {
+                result = AddRawBufferView(buffer, fileBuffer.data(), size);
+            } else {
+                fmt::printf("Warning: Couldn't read %lu bytes from %s, skipping\n", size, filename);
+            }
+        } else {
+            fmt::printf("Warning: Couldn't open texture file %s, skipping\n", filename);
+        }
+        // note that we persist here not only success, but also failure, as nullptr
+        filenameToBufferView[filename] = result;
+        return result;
+    }
+
+
     template<class T>
     std::shared_ptr<AccessorData> AddAccessorWithView(
         BufferViewData &bufferView, const GLType &type, const std::vector<T> &source)
@@ -164,8 +193,13 @@ struct GLTFData
     }
 
     const bool isGlb;
+
+    // cache BufferViewData instances that've already been created from a given filename
+    const std::map<std::string, std::shared_ptr<BufferViewData>> filenameToBufferView;
+
     std::shared_ptr<std::vector<uint8_t> > binary;
 
+
     Holder<BufferData>     buffers;
     Holder<BufferViewData> bufferViews;
     Holder<AccessorData>   accessors;
@@ -332,23 +366,13 @@ ModelData *Raw2Gltf(
 
             ImageData *source = nullptr;
             if (options.outputBinary) {
-                std::ifstream file(texFilename, std::ios::binary | std::ios::ate);
-                if (file) {
-                    std::streamsize size = file.tellg();
-                    file.seekg(0, std::ios::beg);
-
-                    std::vector<char> fileBuffer(size);
-                    if (file.read(fileBuffer.data(), size)) {
-                        auto bufferView = gltf->AddRawBufferView(buffer, fileBuffer.data(), size);
-                        source = new ImageData(textureName, *bufferView, "image/png");
-                    } else {
-                        fmt::printf("Warning: Couldn't read %lu bytes from %s, skipping\n", size, texFilename.c_str());
-                    }
-                } else {
-                    fmt::printf("Warning: Couldn't open texture file %s, skipping\n", texFilename.c_str());
+                auto bufferView = gltf->AddBufferViewForFile(buffer, texFilename);
+                if (bufferView) {
+                    source = new ImageData(textureName, *bufferView, "image/png");
                 }
+
             } else {
-                // TODO: write to buffer.bin?
+                // TODO: don't add .ktx here; try to work out a reasonable relative path.
                 source = new ImageData(textureName, textureName + ".ktx");
             }
             if (!source) {