From 42e28fa010a4dd4615e430b3aa1e4a51000e9f23 Mon Sep 17 00:00:00 2001
From: Brad Davis <bdavis@saintandreas.org>
Date: Fri, 30 Sep 2016 15:48:10 -0700
Subject: [PATCH] Fix crash in initializing texture transfer thread

---
 libraries/gpu-gl/src/gpu/gl/GLTextureTransfer.cpp | 13 ++++++++++++-
 libraries/gpu-gl/src/gpu/gl/GLTextureTransfer.h   | 12 ++++++++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/libraries/gpu-gl/src/gpu/gl/GLTextureTransfer.cpp b/libraries/gpu-gl/src/gpu/gl/GLTextureTransfer.cpp
index 75af08d9a3..45403f4d4d 100644
--- a/libraries/gpu-gl/src/gpu/gl/GLTextureTransfer.cpp
+++ b/libraries/gpu-gl/src/gpu/gl/GLTextureTransfer.cpp
@@ -18,7 +18,6 @@
 std::unordered_map<TexturePointer, nvtxRangeId_t> _map;
 #endif
 
-//#define TEXTURE_TRANSFER_PBOS
 
 #ifdef TEXTURE_TRANSFER_PBOS
 #define TEXTURE_TRANSFER_BLOCK_SIZE (64 * 1024)
@@ -62,11 +61,16 @@ void GLTextureTransferHelper::transferTexture(const gpu::TexturePointer& texture
 void GLTextureTransferHelper::setup() {
 #ifdef THREADED_TEXTURE_TRANSFER
     _context.makeCurrent();
+
+#ifdef TEXTURE_TRANSFER_FORCE_DRAW
+    // FIXME don't use opengl 4.5 DSA functionality without verifying it's present
     glCreateRenderbuffers(1, &_drawRenderbuffer);
     glNamedRenderbufferStorage(_drawRenderbuffer, GL_RGBA8, 128, 128);
     glCreateFramebuffers(1, &_drawFramebuffer);
     glNamedFramebufferRenderbuffer(_drawFramebuffer, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, _drawRenderbuffer);
     glCreateFramebuffers(1, &_readFramebuffer);
+#endif
+
 #ifdef TEXTURE_TRANSFER_PBOS
     std::array<GLuint, TEXTURE_TRANSFER_PBO_COUNT> pbos;
     glCreateBuffers(TEXTURE_TRANSFER_PBO_COUNT, &pbos[0]);
@@ -84,7 +88,9 @@ void GLTextureTransferHelper::setup() {
 void GLTextureTransferHelper::shutdown() {
 #ifdef THREADED_TEXTURE_TRANSFER
     _context.makeCurrent();
+#endif
 
+#ifdef TEXTURE_TRANSFER_FORCE_DRAW
     glNamedFramebufferRenderbuffer(_drawFramebuffer, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, 0);
     glDeleteFramebuffers(1, &_drawFramebuffer);
     _drawFramebuffer = 0;
@@ -165,6 +171,11 @@ bool GLTextureTransferHelper::process() {
         }
 
         gltexture->finishTransfer();
+
+#ifdef TEXTURE_TRANSFER_FORCE_DRAW
+        // FIXME force a draw on the texture transfer thread before passing the texture to the main thread for use
+#endif
+
 #ifdef THREADED_TEXTURE_TRANSFER
         clientWait();
 #endif
diff --git a/libraries/gpu-gl/src/gpu/gl/GLTextureTransfer.h b/libraries/gpu-gl/src/gpu/gl/GLTextureTransfer.h
index 289aec40bb..a23c282fd4 100644
--- a/libraries/gpu-gl/src/gpu/gl/GLTextureTransfer.h
+++ b/libraries/gpu-gl/src/gpu/gl/GLTextureTransfer.h
@@ -21,6 +21,14 @@
 #define THREADED_TEXTURE_TRANSFER
 #endif
 
+#ifdef THREADED_TEXTURE_TRANSFER
+// FIXME when sparse textures are enabled, it's harder to force a draw on the transfer thread
+// also, the current draw code is implicitly using OpenGL 4.5 functionality
+//#define TEXTURE_TRANSFER_FORCE_DRAW
+// FIXME PBO's increase the complexity and don't seem to work reliably
+//#define TEXTURE_TRANSFER_PBOS
+#endif
+
 namespace gpu { namespace gl {
 
 using TextureList = std::list<TexturePointer>;
@@ -43,11 +51,15 @@ public:
 private:
 #ifdef THREADED_TEXTURE_TRANSFER
     ::gl::OffscreenContext _context;
+#endif
+
+#ifdef TEXTURE_TRANSFER_FORCE_DRAW
     // Framebuffers / renderbuffers for forcing access to the texture on the transfer thread
     GLuint _drawRenderbuffer { 0 };
     GLuint _drawFramebuffer { 0 };
     GLuint _readFramebuffer { 0 };
 #endif
+
     // A mutex for protecting items access on the render and transfer threads
     Mutex _mutex;
     // Commands that have been submitted for execution on the texture transfer thread