From ec5f6ead3f6be2c0acc3bd032eb290fa47612b7a Mon Sep 17 00:00:00 2001
From: Swung0x48 <swung0x48@outlook.com>
Date: Tue, 29 Sep 2026 12:26:10 -0400
Subject: [PATCH] [Test] (P11 M2):
 TextureEmit.MoreThanKMaxDirtyRectsCollapsesToTheBoxWithRegionCountZero keeps
 its name and pins the one collapse left - a footprint larger than a record
 carries falls back to the storage's rect list

---
 MobileGL/MG_Test/Pipe/TextureEmitTest.cpp | 30 +++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/MobileGL/MG_Test/Pipe/TextureEmitTest.cpp b/MobileGL/MG_Test/Pipe/TextureEmitTest.cpp
index fc020d87..d75bcd24 100644
--- a/MobileGL/MG_Test/Pipe/TextureEmitTest.cpp
+++ b/MobileGL/MG_Test/Pipe/TextureEmitTest.cpp
@@ -214,6 +214,7 @@ TEST(TextureEmit, TheEmitterIsOneNeverDestroyedProcessSingleton) {
     X(TextureEmit, AScatteredUploadCarriesTheLevelShadowsStridesAndNotZero)                        \
     X(TextureEmit, AWholeLevelUploadCarriesZeroStrides)                                            \
     X(TextureEmit, MoreWritesThanTheRectListKeepsCrossAsTheExactFootprint)                         \
+    X(TextureEmit, MoreThanKMaxDirtyRectsCollapsesToTheBoxWithRegionCountZero)                     \
     X(TextureEmit, ASinglePartialWriteCarriesItsBoxAsOneRegion)                                    \
     X(TextureEmit, ALevelTooLargeForTheStageChunkIsCutIntoSlabs)                                   \
     X(TextureEmit, AnUploadThroughAViewKeysOnTheStorageOwner)                                      \
@@ -609,6 +610,35 @@ TEST(TextureEmit, MoreWritesThanTheRectListKeepsCrossAsTheExactFootprint) {
     }
 }
 
+// P11 M2: THE NAME IS P4a's AND IT STAYS TRUE, ONE LEVEL UP. The case it named - more writes than
+// the rect list keeps - now crosses as the exact footprint (the case above). What still collapses
+// is a footprint larger than one record may carry (kMGPipeMaxPendingUploadRegions): the emitter
+// falls back to the storage's rect list, which covers the writes - so, as before, the storage's own
+// answer is the oracle, read BEFORE the drain clears the level, and 0 means "the union box is the
+// whole story". 16,384 one-texel writes two texels apart are that many disjoint boxes.
+TEST(TextureEmit, MoreThanKMaxDirtyRectsCollapsesToTheBoxWithRegionCountZero) {
+    TextureScope scope;
+    const auto texture = MakeTexture2D(91, 256);
+    for (Int y = 0; y < 256; y += 2) {
+        for (Int x = 0; x < 256; x += 2) {
+            texture->MarkStorageDirtyRegion(TextureUploadTarget::Texture2D, 0, IntVec3{x, y, 0},
+                                            IntVec3{1, 1, 1});
+        }
+    }
+    Vector<MipmapDirtyRegion> footprint;
+    texture->GetStorageDirtyFootprint(TextureUploadTarget::Texture2D, 0, footprint);
+    ASSERT_GT(footprint.size(), static_cast<SizeT>(kMGPipeMaxPendingUploadRegions))
+        << "the writes must outgrow one record, or this case pins the footprint path instead";
+    MipmapDirtyRegion oracle[MipmapStorage::kMaxDirtyRects];
+    const SizeT oracleCount = texture->GetStorageDirtyRects(TextureUploadTarget::Texture2D, 0, oracle,
+                                                            MipmapStorage::kMaxDirtyRects);
+    EXPECT_LE(oracleCount, MipmapStorage::kMaxDirtyRects);
+    Textures().DrainTextureSubData(Ctx());
+    EXPECT_EQ(Textures().LastSubData().RegionCount, static_cast<Uint32>(oracleCount))
+        << "the emitted region count is not the storage's own answer";
+    EXPECT_EQ(Textures().LastRegions().size(), oracleCount);
+}
+
 // P11 M2: A SINGLE PARTIAL BOX CARRIES ITSELF AS ONE REGION. "0 regions" is the whole-level
 // spelling only, so the applier's accumulation - which makes an entry box-only the moment one
 // contribution carries no list - cannot widen two exact contributions into their union box.