Adds a glfwInitVulkan function to provide a vkGetInstanceProcAddr.

This allows an application to handle locating and loading a vulkan loader,
but still use GLFW to handle the native window support.

README.md

@@ -116,6 +116,7 @@ information on what to include when reporting a bug.
 
 ## Changelog
 
+ - Added `glfwInitVulkan` to init Vulkan with a custom loader (#1374)
  - Added `GLFW_PLATFORM` init hint for runtime platform selection (#1958)
  - Added `GLFW_ANY_PLATFORM`, `GLFW_PLATFORM_WIN32`, `GLFW_PLATFORM_COCOA`,
    `GLFW_PLATFORM_WAYLAND`, `GLFW_PLATFORM_X11` and `GLFW_PLATFORM_NULL` symbols to

include/GLFW/glfw3.h

@@ -6081,6 +6081,29 @@ GLFWAPI int glfwExtensionSupported(const char* extension);
  */
 GLFWAPI GLFWglproc glfwGetProcAddress(const char* procname);
 
+/*! @brief Initializes the Vulkan support with the given Vulkan loader
+ *  function.
+ *
+ *  The passed pointer must be a valid vkGetInstanceProcAddr function
+ *  retrieved from the Vulkan loader. Calling this funciton is optional, and
+ *  GLFW attempts to locate the Vulkan loader automatically if this function is
+ *  not called explicitely.
+ *
+ *  @return `GLFW_TRUE` if initializing Vulkan was successful, or `GLFW_FALSE`
+ *  otherwise.
+ *
+ *  @errors Possible errors include @ref GLFW_NOT_INITIALIZED.
+ *
+ *  @thread_safety This function may be called from any thread.
+ *
+ *  @sa @ref vulkan_support
+ *
+ *  @since Added in version 3.3.
+ *
+ *  @ingroup vulkan
+ */
+GLFWAPI int glfwInitVulkan(void* getInstanceProcAddr);
+
 /*! @brief Returns whether the Vulkan loader and an ICD have been found.
  *
  *  This function returns whether the Vulkan loader and any minimally functional

src/vulkan.c

@@ -35,6 +35,7 @@
 
 #define _GLFW_FIND_LOADER    1
 #define _GLFW_REQUIRE_LOADER 2
+#define _GLFW_SKIP_LOADER    3
 
 
 //////////////////////////////////////////////////////////////////////////
@@ -51,6 +52,7 @@ GLFWbool _glfwInitVulkan(int mode)
         return GLFW_TRUE;
 
 #if !defined(_GLFW_VULKAN_STATIC)
+    if (mode != _GLFW_SKIP_LOADER) {
 #if defined(_GLFW_VULKAN_LIBRARY)
       _glfw.vk.handle = _glfwPlatformLoadModule(_GLFW_VULKAN_LIBRARY);
 #elif defined(_GLFW_WIN32)
@@ -72,6 +74,8 @@ GLFWbool _glfwInitVulkan(int mode)
 
       _glfw.vk.GetInstanceProcAddr = (PFN_vkGetInstanceProcAddr)
           _glfwPlatformGetModuleSymbol(_glfw.vk.handle, "vkGetInstanceProcAddr");
+    } // mode != _GLFW_SKIP_LOADER
+
     if (!_glfw.vk.GetInstanceProcAddr)
     {
         _glfwInputError(GLFW_API_UNAVAILABLE,
@@ -217,6 +221,16 @@ const char* _glfwGetVulkanResultString(VkResult result)
 //////                        GLFW public API                       //////
 //////////////////////////////////////////////////////////////////////////
 
+GLFWAPI int glfwInitVulkan(void* getInstanceProcAddr) {
+    _GLFW_REQUIRE_INIT_OR_RETURN(GLFW_FALSE);
+#if !defined(_GLFW_VULKAN_STATIC)
+    _glfw.vk.GetInstanceProcAddr = getInstanceProcAddr;
+    return _glfwInitVulkan(_GLFW_SKIP_LOADER);
+#else
+    return GLFW_TRUE;
+#endif
+}
+
 GLFWAPI int glfwVulkanSupported(void)
 {
     _GLFW_REQUIRE_INIT_OR_RETURN(GLFW_FALSE);