filter out VSM variant for unlit materials DEPTH shaders

The VSM variant is never needed for unlit materials, it was filtered
out correctly for color shaders but not for the depth shaders.
This removes 4 variants from all unlit materials.

Also improve matinfo variants output.

NEW_RELEASE_NOTES.md

@@ -12,4 +12,5 @@ appropriate header in [RELEASE_NOTES.md](./RELEASE_NOTES.md).
 - fog: fog color now takes exposure and IBL intensity into account [⚠️ **Recompile Materials**].
 - materials: implement cascades debugging as a post-process [⚠️ **Recompile Materials**].
 - materials: use 9 digits or less for floats [⚠️ **Recompile Materials**].
-- gltfio: fix skinning when objects are far from the origin
+- gltfio: fix skinning when objects are far from the origin
+- materials: remove 4 unneeded variants from `unlit` materials [⚠️ **Recompile Materials**].

filament/src/details/Material.cpp

@@ -282,12 +282,14 @@ FMaterial::FMaterial(FEngine& engine, const Material::Builder& builder)
     mIsDefaultMaterial = builder->mDefaultMaterial;
 
     // pre-cache the shared variants -- these variants are shared with the default material.
+    // (note: the default material is unlit, so only unlit variants can be shared)
     if (UTILS_UNLIKELY(!mIsDefaultMaterial && !mHasCustomDepthShader)) {
+        FMaterial const* const pMaterial = engine.getDefaultMaterial();
         auto& cachedPrograms = mCachedPrograms;
         for (Variant::type_t k = 0, n = VARIANT_COUNT; k < n; ++k) {
             const Variant variant(k);
-            if (Variant::isValidDepthVariant(variant)) {
-                FMaterial const* const pMaterial = engine.getDefaultMaterial();
+            if (Variant::isValidDepthVariant(variant) &&
+                (Variant::filterVariant(variant, false) == variant)) {
                 pMaterial->prepareProgram(variant);
                 cachedPrograms[k] = pMaterial->getProgram(variant);
             }

libs/filabridge/include/private/filament/Variant.h

@@ -217,6 +217,10 @@ struct Variant {
     static constexpr Variant filterVariant(Variant variant, bool isLit) noexcept {
         // special case for depth variant
         if (isValidDepthVariant(variant)) {
+            if (!isLit) {
+                // if we're unlit, we never need the VSM variant
+                return variant & ~VSM;
+            }
             return variant;
         }
         if (isSSRVariant(variant)) {

libs/matdbg/src/CommonWriter.cpp

@@ -46,7 +46,11 @@ std::string formatVariantString(Variant variant, MaterialDomain domain) noexcept
         if (variant.key & Variant::SRE) variantString += "SRE|";
         if (variant.key & Variant::SKN) variantString += "SKN|";
         if (variant.key & Variant::DEP) variantString += "DEP|";
-        if (variant.key & Variant::FOG) variantString += "FOG|";
+        if (variant.key & Variant::DEP) {
+            if (variant.key & Variant::PCK) variantString += "PCK|";
+        } else {
+            if (variant.key & Variant::FOG) variantString += "FOG|";
+        }
         if (variant.key & Variant::VSM) variantString += "VSM|";
         variantString = variantString.substr(0, variantString.length() - 1);
     }