[Perf] (MG_Backend/DirectVulkan): skip the per-draw sampled-texture walk when the bound set is unchanged (texture-bind generation + program state version); CollectSampledTextures 5.0%->0.2%, fps 228->249

MobileGL/MG_State/GLState/Core.h

@@ -102,6 +102,10 @@ namespace MobileGL {
                 const ImageTextureBinding& GetImageTextureBinding(Int unit) const;
                 void NoteTextureUnitTouched(Int unit) { m_textureState.NoteUnitTouched(unit); }
                 Int GetMaxTouchedTextureUnit() const { return m_textureState.GetMaxTouchedUnit(); }
+                // Monotonic counter bumped whenever a texture bind/unbind/delete changes which
+                // texture is bound at a unit; lets a backend skip re-resolving an unchanged
+                // per-draw sampled-texture set.
+                Uint64 GetTextureBindGeneration() const { return m_textureState.GetTextureBindGeneration(); }
                 Bool ValidateTextureName(Uint index) const;
                 Bool ValidateTextureObject(Uint index) const;
                 Int GetActiveTextureUnit() const;

MobileGL/MG_State/GLState/TextureState/TextureState.cpp

@@ -104,6 +104,10 @@ namespace MobileGL::MG_State::GLState {
                         imageBinding.Bind(nullptr, 0, GL_FALSE, 0, GL_READ_ONLY, GL_R8);
                     }
                 }
+                // Deleting a texture unbinds it from every unit above; treat that as a binding
+                // change so a cached sampled-texture set (which may hold this raw pointer) is
+                // re-resolved instead of dangling.
+                BumpTextureBindGeneration();
                 m_textureObjects.erase(index);
             }
             m_indexGenerator.Delete(index);

MobileGL/MG_State/GLState/TextureState/TextureState.h

@@ -63,10 +63,20 @@ namespace MobileGL::MG_State::GLState {
         // can stop there instead of walking all MAX_TEXTURE_IMAGE_UNITS units.
         void NoteUnitTouched(Int unit) {
             if (unit > m_maxTouchedUnit && unit < MAX_TEXTURE_IMAGE_UNITS) m_maxTouchedUnit = unit;
+            // Every texture/sampler bind entry point (glBindTexture / glBindTextureUnit /
+            // glBindTextures / glBindSampler) routes through here, so bumping the generation here
+            // - plus in MarkTextureObjectForDeletion for delete-unbind - covers every change to
+            // which texture is bound at which unit. A backend that has cached the per-draw
+            // sampled-texture set can compare this against a snapshot to skip re-resolving it when
+            // no bind changed (the block atlas + lightmap stay bound across a whole terrain batch).
+            ++m_textureBindGeneration;
         }
         Int GetMaxTouchedUnit() const { return m_maxTouchedUnit; }
+        Uint64 GetTextureBindGeneration() const { return m_textureBindGeneration; }
+        void BumpTextureBindGeneration() { ++m_textureBindGeneration; }
 
     private:
+        Uint64 m_textureBindGeneration = 0;
         Int m_maxTouchedUnit = -1;
         Int m_activeTextureUnit = 0;
         Array<TextureUnit, MAX_TEXTURE_IMAGE_UNITS> m_textureUnits;