matdbg: opt-in via environment variable.

RELEASE_NOTES.md

@@ -10,8 +10,9 @@ A new header is inserted each time a *tag* is created.
 - gltfio: Fixed several limitations with ubershader mode.
 - gltfio: Fixed a transforms issue with non-uniform scale.
 - webgl: Fixed an issue with JPEG textures.
-- Windows: fix link error in debug builds.
-- The web-based material inspector now allows editing GLSL and MSL code.
+- Windows: Fix link error in debug builds.
+- matdbg: Web server must now be enabled with an environment variable.
+- matdbg: Added support for editing GLSL and MSL code.
 
 ## v1.3.2
 

filament/src/Engine.cpp

@@ -401,9 +401,10 @@ int FEngine::loop() {
     }
 
 #if FILAMENT_ENABLE_MATDBG
-    // Disable the web server for regression tests that occur in hermetic environments.
-    if (mBackend != backend::Backend::NOOP) {
-        debug.server = new matdbg::DebugServer(mBackend, 8080);
+    const char* portString = getenv("FILAMENT_MATDBG_PORT");
+    if (portString != nullptr) {
+        const int port = atoi(portString);
+        debug.server = new matdbg::DebugServer(mBackend, port);
 
         // Sometimes the server can fail to spin up (e.g. if the above port is already in use).
         // When this occurs, carry onward, developers can look at civetweb.txt for details.

libs/matdbg/README.md

@@ -12,7 +12,11 @@
 
 ## User Instructions
 
-Simply launch any app that links against a debug build of a Filament, and point your web browser to
+First set an environment variable as follows. In Windows, use `set` instead of `export`.
+
+    export FILAMENT_MATDBG_PORT=8080
+
+Next, launch any app that links against a debug build of a Filament and point your web browser to
 http://localhost:8080.
 
 After selecting a material and shader variant, you can view the GLSL, MSL, and SPIR-V code that was
@@ -167,8 +171,6 @@ they appear in the package, where each API (GL / VK / Metal) has its own list.
 
 ## Wish List
 
-- Allow disabling the server at run time when using a build that has FILAMENT_ENABLE_MATDBG.
-    - Maybe this can be an environment variable (extern char \*\*environ) that also controls the port number.
 - Allow SPIR-V edits.
 - Allow viewing GLSL transpiled from SPIR-V.
     - Also stop piggybacking on `type=glsl` for Metal Shading Language.