From 305bfb36d83d9742ba3d12f4e3928ad338c3d8b0 Mon Sep 17 00:00:00 2001
From: Eliza Velasquez <exv@google.com>
Date: Tue, 30 Apr 2024 12:49:47 -0700
Subject: [PATCH] Fix broken ImGui on web

I was unfortunately naive about the way that Filament handled external textures
on non-GLES platforms. This fix restricts the changes to Android (which is the
only place this change is required in the first place). Long story short, the
change broke WebGL. Desktop seems to be unaffected.
---
 NEW_RELEASE_NOTES.md                       | 2 ++
 libs/filagui/include/filagui/ImGuiHelper.h | 6 ++++--
 libs/filagui/src/ImGuiHelper.cpp           | 9 ++++++++-
 3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/NEW_RELEASE_NOTES.md b/NEW_RELEASE_NOTES.md
index 4a1a9c7fa7..188a51f366 100644
--- a/NEW_RELEASE_NOTES.md
+++ b/NEW_RELEASE_NOTES.md
@@ -7,3 +7,5 @@ for next branch cut* header.
 appropriate header in [RELEASE_NOTES.md](./RELEASE_NOTES.md).
 
 ## Release notes for next branch cut
+
+- filagui: Fix regression which broke WebGL
diff --git a/libs/filagui/include/filagui/ImGuiHelper.h b/libs/filagui/include/filagui/ImGuiHelper.h
index 9ad4f0765e..3f55ac77bb 100644
--- a/libs/filagui/include/filagui/ImGuiHelper.h
+++ b/libs/filagui/include/filagui/ImGuiHelper.h
@@ -84,12 +84,14 @@ public:
       filament::View* mView; // The view is owned by the client.
       filament::Scene* mScene;
       filament::Material* mMaterial2d = nullptr;
+      std::vector<filament::MaterialInstance*> mMaterial2dInstances;
+#ifdef __ANDROID__
       filament::Material* mMaterialExternal = nullptr;
+      std::vector<filament::MaterialInstance*> mMaterialExternalInstances;
+#endif
       filament::Camera* mCamera = nullptr;
       std::vector<filament::VertexBuffer*> mVertexBuffers;
       std::vector<filament::IndexBuffer*> mIndexBuffers;
-      std::vector<filament::MaterialInstance*> mMaterial2dInstances;
-      std::vector<filament::MaterialInstance*> mMaterialExternalInstances;
       utils::Entity mRenderable;
       utils::Entity mCameraEntity;
       filament::Texture* mTexture = nullptr;
diff --git a/libs/filagui/src/ImGuiHelper.cpp b/libs/filagui/src/ImGuiHelper.cpp
index 935ae138a4..1a88013125 100644
--- a/libs/filagui/src/ImGuiHelper.cpp
+++ b/libs/filagui/src/ImGuiHelper.cpp
@@ -64,10 +64,12 @@ ImGuiHelper::ImGuiHelper(Engine* engine, filament::View* view, const Path& fontP
             .package(FILAGUI_RESOURCES_UIBLIT_DATA, FILAGUI_RESOURCES_UIBLIT_SIZE)
             .constant("external", false)
             .build(*engine);
+#ifdef __ANDROID__
     mMaterialExternal = Material::Builder()
             .package(FILAGUI_RESOURCES_UIBLIT_DATA, FILAGUI_RESOURCES_UIBLIT_SIZE)
             .constant("external", true)
             .build(*engine);
+#endif
 
     // If the given font path is invalid, ImGui will silently fall back to proggy, which is a
     // tiny "pixel art" texture that is compiled into the library.
@@ -134,10 +136,12 @@ ImGuiHelper::~ImGuiHelper() {
         mEngine->destroy(mi);
     }
     mEngine->destroy(mMaterial2d);
+#ifdef __ANDROID__
     for (auto& mi : mMaterialExternalInstances) {
         mEngine->destroy(mi);
     }
     mEngine->destroy(mMaterialExternal);
+#endif
     mEngine->destroy(mTexture);
     for (auto& vb : mVertexBuffers) {
         mEngine->destroy(vb);
@@ -229,13 +233,16 @@ void ImGuiHelper::processImGuiCommands(ImDrawData* commands, const ImGuiIO& io)
                 auto texture = (Texture const*)pcmd.TextureId;
                 const char* uniformName;
                 MaterialInstance* materialInstance;
+#ifdef __ANDROID__
                 if (texture && texture->getTarget() == Texture::Sampler::SAMPLER_EXTERNAL) {
                     if (materialExternalIndex == mMaterialExternalInstances.size()) {
                         mMaterialExternalInstances.push_back(mMaterialExternal->createInstance());
                     }
                     uniformName = "albedoExternal";
                     materialInstance = mMaterialExternalInstances[materialExternalIndex++];
-                } else {
+                } else
+#endif
+                {
                     if (material2dIndex == mMaterial2dInstances.size()) {
                         mMaterial2dInstances.push_back(mMaterial2d->createInstance());
                     }