[Revert] (MG_Backend/DirectVulkan): back out the gl_FragCoord default-framebuffer origin fix - correct, but it costs DirectVulkan a large order-dependent slowdown that is not yet root-caused

MobileGL/MG_Backend/DirectVulkan/Renderer/ProgramFactory.h

@@ -53,13 +53,6 @@ namespace MobileGL::MG_Backend::DirectVulkan {
             // recorded while GL transform feedback is active, so plain draws keep the
             // undecorated variant.
             XfbCapture = 1 << 6,
-            // Rewrites the fragment stage's gl_FragCoord reads to GL's bottom-left window
-            // origin. Vulkan's gl_FragCoord.y IS the framebuffer row being written, and the
-            // default framebuffer's image is stored in display (top-left) order, so a shader
-            // that reads gl_FragCoord there sees `height - y_GL`. Set together with
-            // PositionYFlip (the two are the same fact about the same draws) except under a
-            // quarter turn, which this renderer does not convert rectangles for either.
-            FragCoordYFlip = 1 << 7,
         };
         using CompileOptionFlags = Flags<CompileOptionBit>;
         using HashType = Uint64;
@@ -274,17 +267,6 @@ namespace MobileGL::MG_Backend::DirectVulkan {
         const VkProgramObject& GetOrCreateProgram(
             const MG_State::GLState::ProgramObject& program, CompileOptionFlags flags);
 
-        // The default framebuffer's current image height, baked as a literal into every
-        // FragCoordYFlip variant (there is no push-constant or specialization channel here, and
-        // adding one for a value that changes only on swapchain recreation would cost the draw
-        // path more than a recompile costs a resize). It is therefore part of those variants'
-        // identity: ComputeHash mixes it in when the bit is set, so a height change re-keys them
-        // and leaves every other program's hash untouched. Setting a NEW height also bumps the
-        // cache-structure epoch, because a caller holding a memoised VkProgramObject* would
-        // otherwise keep using a module compiled against the old height.
-        void SetDefaultFramebufferHeight(Uint32 height);
-        Uint32 GetDefaultFramebufferHeight() const { return m_defaultFramebufferHeight; }
-
         // Bumped whenever m_cache's STRUCTURE changes (any insert or erase): the cache is
         // an open-addressing map holding entries by value, so both moves existing entries.
         // A caller that memoised a VkProgramObject* may keep dereferencing it only while
@@ -342,9 +324,6 @@ namespace MobileGL::MG_Backend::DirectVulkan {
         // True only when the logical device enabled both
         // shaderStorageImageReadWithoutFormat and shaderStorageImageWriteWithoutFormat.
         Bool m_unformattedFloatStorageImagesEnabled = false;
-        // See SetDefaultFramebufferHeight. 0 means "not known yet"; the FragCoordYFlip bit is
-        // never set before the swapchain exists, so no variant can be compiled against it.
-        Uint32 m_defaultFramebufferHeight = 0;
         mutable ProgramLookupCache m_lastLookup;
         // Monotonic frame-boundary counter (bumped in OnFrameBoundary) for cache aging.
         Uint64 m_frameCounter = 0;