Fix crash when using Filamat lite library (#1780)

android/samples/material-builder/app/build.gradle

@@ -73,6 +73,13 @@ android {
         }
     }
 
+    // The filamat library has two variants: full and lite. Here we default to the "full" variant.
+    // Replace "full" with "lite" to use the filamat-lite variant, which has a smaller binary size
+    // but comes with certain restrictions. See "Filamat Lite" in libs/filamat/README.md.
+    defaultConfig {
+        missingDimensionStrategy 'functionality', 'full'
+    }
+
     // We use the .filamat extension for materials compiled with matc
     // Telling aapt to not compress them allows to load them efficiently
     aaptOptions {

android/samples/material-builder/app/src/main/java/com/google/android/filament/material_builder/MainActivity.kt

@@ -212,6 +212,10 @@ class MainActivity : Activity() {
                         "    material.clearCoat = 1.0;\n" +
                         "}\n")
 
+                // Turn off shader code optimization so this sample is compatible with the "lite"
+                // variant of the filamat library.
+                .optimization(MaterialBuilder.Optimization.NONE)
+
                 .build()
 
         if (matPackage.isValid) {

libs/filamat/src/sca/GLSLToolsLite.cpp

@@ -79,6 +79,10 @@ bool GLSLToolsLite::findProperties(
         filament::backend::ShaderType type,
         const utils::CString& material,
         MaterialBuilder::PropertyList& properties) const noexcept {
+    if (material.empty()) {
+        return true;
+    }
+
     const std::string shaderCode = stripComments(material.c_str());
 
     size_t start = 0, end = 0;