From 5031d0686ae30d8e014d4683f36b762c4a67d95e Mon Sep 17 00:00:00 2001
From: "David G. Yu" <dyu@pixar.com>
Date: Sun, 23 Feb 2014 21:21:25 -0800
Subject: [PATCH] Fixed OpenCL initialization to be slightly more robust.

On platforms with multiple devices (e.g. OS X Mavericks
with both Intel and Discrete GPU CL devices) we must
create the context and command queue with the correct
device in order to share resources with GL.
---
 examples/common/clInit.h | 40 ++++++++++++++++++++++++++++++++--------
 1 file changed, 32 insertions(+), 8 deletions(-)

diff --git a/examples/common/clInit.h b/examples/common/clInit.h
index 38d353c4..20ef7367 100644
--- a/examples/common/clInit.h
+++ b/examples/common/clInit.h
@@ -53,8 +53,7 @@ static bool initCL(cl_context *clContext, cl_command_queue *clQueue)
         printf("No OpenCL platform found.\n");
         return false;
     }
-    cl_platform_id *clPlatformIDs;
-    clPlatformIDs = new cl_platform_id[num_platforms];
+    cl_platform_id *clPlatformIDs = new cl_platform_id[num_platforms];
     ciErrNum = clGetPlatformIDs(num_platforms, clPlatformIDs, NULL);
     char chBuffer[1024];
     for (cl_uint i = 0; i < num_platforms; ++i) {
@@ -63,9 +62,6 @@ static bool initCL(cl_context *clContext, cl_command_queue *clQueue)
             cpPlatform = clPlatformIDs[i];
         }
     }
-    // -------------
-    cl_device_id clDevice;
-    clGetDeviceIDs(cpPlatform, CL_DEVICE_TYPE_GPU, 1, &clDevice, NULL);
 
 #if defined(_WIN32)
     cl_context_properties props[] = {
@@ -91,14 +87,42 @@ static bool initCL(cl_context *clContext, cl_command_queue *clQueue)
 #endif
     delete[] clPlatformIDs;
 
-    // XXX context creation should be moved to client code
-    *clContext = clCreateContext(props, 1, &clDevice, NULL, NULL, &ciErrNum);
+#if defined(__APPLE__)
+    *clContext = clCreateContext(props, 0, NULL, clLogMessagesToStdoutAPPLE, NULL, &ciErrNum);
     if (ciErrNum != CL_SUCCESS) {
         printf("Error %d in clCreateContext\n", ciErrNum);
         return false;
     }
 
-    *clQueue = clCreateCommandQueue(*clContext, clDevice, 0, &ciErrNum);
+    size_t devicesSize = 0;
+    clGetGLContextInfoAPPLE(*clContext, kCGLContext, CL_CGL_DEVICES_FOR_SUPPORTED_VIRTUAL_SCREENS_APPLE, 0, NULL, &devicesSize);
+    int numDevices = int(devicesSize / sizeof(cl_device_id));
+    if (numDevices == 0) {
+        printf("No sharable devices.\n");
+        return false;
+    }
+    cl_device_id *clDevices = new cl_device_id[numDevices];
+    clGetGLContextInfoAPPLE(*clContext, kCGLContext, CL_CGL_DEVICES_FOR_SUPPORTED_VIRTUAL_SCREENS_APPLE, numDevices * sizeof(cl_device_id), clDevices, NULL);
+#else
+    cl_uint numDevices = 0;
+    clGetDeviceIDs(cpPlatform, CL_DEVICE_TYPE_GPU, 0, NULL, &numDevices);
+    if (numDevices == 0) {
+        printf("No sharable devices.\n");
+        return false;
+    }
+    cl_device_id *clDevices = new cl_device_id[numDevices];
+    clGetDeviceIDs(cpPlatform, CL_DEVICE_TYPE_GPU, numDevices, clDevices, NULL);
+
+    *clContext = clCreateContext(props, numDevices, clDevices, NULL, NULL, &ciErrNum);
+    if (ciErrNum != CL_SUCCESS) {
+        printf("Error %d in clCreateContext\n", ciErrNum);
+        delete[] clDevices;
+        return false;
+    }
+#endif
+
+    *clQueue = clCreateCommandQueue(*clContext, clDevices[0], 0, &ciErrNum);
+    delete[] clDevices;
     if (ciErrNum != CL_SUCCESS) {
         printf("Error %d in clCreateCommandQueue\n", ciErrNum);
         return false;