fix X11 access on wayland (isl-org#7209)

* fix X11 access under Wayland
* show glewInit error details
* ignore GLEW_ERROR_NO_GLX_DISPLAY as not required on Wayland
---------
Co-authored-by: Christian Rauch <Rauch.Christian@gmx.de>

Author: christian-rauch

cpp/open3d/visualization/gui/NativeLinux.cpp

@@ -10,6 +10,7 @@
 #include "Application.h"
 #include "Native.h"
 #define GLFW_EXPOSE_NATIVE_X11 1
+#define GLFW_EXPOSE_NATIVE_WAYLAND 1
 #include <GLFW/glfw3native.h>
 #include <memory.h>
 
@@ -18,20 +19,31 @@ namespace visualization {
 namespace gui {
 
 void* GetNativeDrawable(GLFWwindow* glfw_window) {
-    return (void*)glfwGetX11Window(glfw_window);
+    const int platform = glfwGetPlatform();
+    if (platform == GLFW_PLATFORM_X11) {
+        return (void*)glfwGetX11Window(glfw_window);
+    } else if (platform == GLFW_PLATFORM_WAYLAND) {
+        return (void*)glfwGetWaylandWindow(glfw_window);
+    } else {
+        return nullptr;
+    }
 }
 
 void PostNativeExposeEvent(GLFWwindow* glfw_window) {
-    Display* d = glfwGetX11Display();
-    auto x11win = glfwGetX11Window(glfw_window);
+    const int platform = glfwGetPlatform();
 
-    XEvent e;
-    memset(&e, 0, sizeof(e));
-    e.type = Expose;
-    e.xexpose.window = x11win;
+    if (platform == GLFW_PLATFORM_X11) {
+        Display* d = glfwGetX11Display();
+        auto x11win = glfwGetX11Window(glfw_window);
 
-    XSendEvent(d, x11win, False, ExposureMask, &e);
-    XFlush(d);
+        XEvent e;
+        memset(&e, 0, sizeof(e));
+        e.type = Expose;
+        e.xexpose.window = x11win;
+
+        XSendEvent(d, x11win, False, ExposureMask, &e);
+        XFlush(d);
+    }
 }
 
 void ShowNativeAlert(const char* message) {

cpp/open3d/visualization/visualizer/VisualizerRender.cpp

@@ -39,8 +39,12 @@ bool Visualizer::InitOpenGL() {
 #endif
 
     glewExperimental = true;
-    if (glewInit() != GLEW_OK) {
-        utility::LogWarning("Failed to initialize GLEW.");
+    const GLenum init_ret = glewInit();
+    if (init_ret != GLEW_OK && init_ret != GLEW_ERROR_NO_GLX_DISPLAY) {
+        const std::string err_msg{
+                reinterpret_cast<const char *>(glewGetErrorString(init_ret))};
+        utility::LogWarning("Failed to initialize GLEW: {} ({})", err_msg,
+                            init_ret);
         return false;
     }