Refactor composite source handling: unify link_composite_source logic and update related pipeline references

aurora-main/lib/gfx/common.cpp

@@ -209,7 +209,7 @@ struct RenderPass {
   bool snapshotColorResolveSource = false;
   bool efbTarget = false;
   // This pass's perspective draws are re-issued by an eye at the composite that samples its
-  // depth copy (link_composite_sources), and skipped where they were recorded.
+  // depth copy (link_composite_source), and skipped where they were recorded.
   bool compositeSource = false;
   std::vector<tex_palette_conv::ConvRequest> paletteConvs;
 };
@@ -954,8 +954,57 @@ void end_offscreen() {
   push_command(CommandType::SetScissor, Command::Data{.setScissor = g_cachedScissor});
 }
 
+// Mario Kart Wii draws a ghost kart by rendering it alone into the cleared EFB, copying the
+// frame's colour and depth out, drawing the race, and blending the copies back with one
+// orthographic quad whose depth comes from the depth copy. That quad is a native effect, so an
+// eye would stamp the desktop's flat image of the ghost over its own view, following the head
+// and cut by the eye's ground. Instead the eye skips the draws of the pass that resolved the
+// depth copy where they were recorded and re-issues them in the composite's place, blended
+// with kCompositeSourceAlpha and depth-tested against its own world: the ghost in stereo,
+// translucent, where the game put it.
+//
+// Linked as the composite is recorded, so a frame without one does no work for it. The source
+// pass is complete by then, and only the current pass ever moves (offscreen suspension), so it
+// is found by the copy it resolved. A source draw without constant-alpha siblings asks for them
+// here; its pipeline's next draw brings them, and until then the eye leaves that draw out.
+static void link_composite_source(const gx::DrawData& composite) noexcept {
+  if (g_currentRenderPass >= g_renderPasses.size()) {
+    return;
+  }
+  static bool linkLogged = false;
+  for (size_t p = g_currentRenderPass; p-- > 0;) {
+    auto& source = g_renderPasses[p];
+    if (!source.efbTarget || source.resolveTarget.get() != composite.uniformReplayLayout.compositeDepthCopy) {
+      continue;
+    }
+    size_t draws = 0;
+    for (const auto& command : source.commands) {
+      if (command.type != CommandType::Draw || command.data.draw.type != ShaderType::GX ||
+          !command.data.draw.gx.uniformReplayLayout.perspective) {
+        continue;
+      }
+      ++draws;
+      if (command.data.draw.gx.stereoCompositeSourcePipeline == 0) {
+        gx::note_composite_source_pipeline(command.data.draw.gx.pipeline);
+      }
+    }
+    if (draws > 0) {
+      source.compositeSource = true;
+      if (!linkLogged) {
+        linkLogged = true;
+        Log.info("Immersive replay: pass {} ({} perspective draws) is re-issued by each eye in place of a "
+                 "composite that samples its depth copy",
+                 p, draws);
+      }
+    }
+    return;
+  }
+}
+
 template <>
 void push_draw_command(gx::DrawData data) {
+  if (data.uniformReplayLayout.compositeDepthCopy != nullptr && stereo_frame_provider_active())
+    UNLIKELY { link_composite_source(data); }
   push_draw_command(ShaderDrawCommand{.type = ShaderType::GX, .gx = data});
 }
 
@@ -1650,66 +1699,6 @@ static bool prepare_stereo_replay_uniforms(const StereoReplayFrame& stereoFrame,
   return true;
 }
 
-// Mario Kart Wii draws a ghost kart by rendering it alone into the cleared EFB, copying the
-// frame's colour and depth out, drawing the race, and blending the copies back with one
-// orthographic quad whose depth comes from the depth copy. That quad is a native effect, so an
-// eye would stamp the desktop's flat image of the ghost over its own view, following the head
-// and cut by the eye's ground. Instead the eye skips the draws of the pass that produced the
-// depth copy where they were recorded and re-issues them in the composite's place, blended
-// with kCompositeSourceAlpha and depth-tested against the eye's own world: the ghost in stereo,
-// translucent, where the game put it. Runs once the frame's passes are complete, on the
-// producer, before the frame is sealed.
-static void link_composite_sources() noexcept {
-  if (g_stereoLocalPlayerCount > 1) {
-    return;
-  }
-  static bool linkLogged = false;
-  for (size_t i = 0; i < g_renderPasses.size(); ++i) {
-    if (!g_renderPasses[i].efbTarget) {
-      continue;
-    }
-    for (auto& command : g_renderPasses[i].commands) {
-      if (command.type != CommandType::Draw || command.data.draw.type != ShaderType::GX) {
-        continue;
-      }
-      auto& layout = command.data.draw.gx.uniformReplayLayout;
-      layout.compositeSourcePass = -1;
-      if (!layout.nativeEfbEffect || layout.perspective || layout.compositeDepthCopy == nullptr) {
-        continue;
-      }
-      for (size_t p = i; p-- > 0;) {
-        auto& source = g_renderPasses[p];
-        if (!source.efbTarget || source.resolveTarget.get() != layout.compositeDepthCopy) {
-          continue;
-        }
-        size_t draws = 0;
-        for (auto& sourceCommand : source.commands) {
-          if (sourceCommand.type != CommandType::Draw || sourceCommand.data.draw.type != ShaderType::GX) {
-            continue;
-          }
-          auto& sourceDraw = sourceCommand.data.draw.gx;
-          if (sourceDraw.uniformReplayLayout.perspective &&
-              gx::resolve_composite_source_pipelines(sourceDraw.configHash, sourceDraw.stereoGhostPipeline,
-                                                     sourceDraw.stereoGhostStencilPipeline)) {
-            ++draws;
-          }
-        }
-        if (draws > 0) {
-          source.compositeSource = true;
-          layout.compositeSourcePass = static_cast<int32_t>(p);
-          if (!linkLogged) {
-            linkLogged = true;
-            Log.info("Immersive replay: pass {} ({} perspective draws) is re-issued by each eye in place of the "
-                     "composite in pass {} that samples its depth copy",
-                     p, draws, i);
-          }
-        }
-        break;
-      }
-    }
-  }
-}
-
 static bool end_batch_impl(const wgpu::CommandEncoder& cmd, bool advanceFrame,
                            const StereoReplayFrame* stereoFrame = nullptr) {
   ZoneScoped;
@@ -1729,9 +1718,6 @@ static bool end_batch_impl(const wgpu::CommandEncoder& cmd, bool advanceFrame,
   const bool stereoPrepared = (stereoFrame == nullptr && !captureStereo) ||
                               prepare_stereo_replay_uniforms(stereoFrame != nullptr ? *stereoFrame : placeholder,
                                                              captureStereo ? &g_pendingLateStereo : nullptr);
-  if (stereoPrepared && (stereoFrame != nullptr || captureStereo)) {
-    link_composite_sources();
-  }
   if (captureStereo && stereoPrepared) {
     g_pendingLateStereo.generation = g_replayBufferGeneration.load(std::memory_order_acquire);
   } else {
@@ -2697,9 +2683,20 @@ static void render_pass_impl(const wgpu::RenderPassEncoder& pass, const std::vec
                    static_cast<int32_t>(top), static_cast<int32_t>(targetSize.height)));
     return std::array<uint32_t, 4>{left, top, right - left, bottom - top};
   };
+  // Composites serve one camera; a multiplayer eye keeps every draw where it was recorded.
+  const bool compositeReplay = overrideTarget && !multiplayer;
+  const bool skipCompositeSource = compositeReplay && renderPasses[idx].compositeSource;
+  const auto find_composite_source = [&](const TextureRef* depthCopy) -> const RenderPass* {
+    for (u32 p = 0; p < idx; ++p) {
+      if (renderPasses[p].compositeSource && renderPasses[p].resolveTarget.get() == depthCopy) {
+        return &renderPasses[p];
+      }
+    }
+    return nullptr;
+  };
   // The perspective draws of a composite's source pass, in the composite's place: their own
   // recorded viewport and scissor, this eye's uniforms, the constant-alpha pipeline sibling,
-  // depth-tested against the world the eye has drawn by now (see link_composite_sources).
+  // depth-tested against the world the eye has drawn by now (see link_composite_source).
   const auto replay_composite_source = [&](const RenderPass& source) {
     const wgpu::Color alpha{stereo_replay::kCompositeSourceAlpha, stereo_replay::kCompositeSourceAlpha,
                             stereo_replay::kCompositeSourceAlpha, stereo_replay::kCompositeSourceAlpha};
@@ -2721,7 +2718,7 @@ static void render_pass_impl(const wgpu::RenderPassEncoder& pass, const std::vec
       if (!draw.uniformReplayLayout.perspective) {
         continue;
       }
-      const gfx::PipelineRef pipeline = stencilTarget ? draw.stereoGhostStencilPipeline : draw.stereoGhostPipeline;
+      const gfx::PipelineRef pipeline = stencilTarget ? draw.stereoCompositeSourcePipeline : draw.compositeSourcePipeline;
       if (pipeline == 0) {
         continue;
       }
@@ -2795,14 +2792,15 @@ static void render_pass_impl(const wgpu::RenderPassEncoder& pass, const std::vec
                             !stereo_replay::subviews_overlap(sourceScissor, playerRegion))) {
           break;
         }
-        // A composite's source pass is drawn at the composite instead (link_composite_sources).
-        if (overrideTarget && renderPasses[idx].compositeSource) {
+        // A composite's source pass is drawn at the composite instead (link_composite_source).
+        if (skipCompositeSource) {
           break;
         }
-        if (overrideTarget && draw.gx.uniformReplayLayout.compositeSourcePass >= 0 &&
-            static_cast<size_t>(draw.gx.uniformReplayLayout.compositeSourcePass) < renderPasses.size()) {
-          replay_composite_source(renderPasses[static_cast<size_t>(draw.gx.uniformReplayLayout.compositeSourcePass)]);
-          break;
+        if (compositeReplay && draw.gx.uniformReplayLayout.compositeDepthCopy != nullptr) {
+          if (const RenderPass* source = find_composite_source(draw.gx.uniformReplayLayout.compositeDepthCopy)) {
+            replay_composite_source(*source);
+            break;
+          }
         }
         const gfx::Range* uniformOverride = nullptr;
         // Only a 2D draw the virtual screen actually claimed carries a stereo

aurora-main/lib/gx/command_processor.cpp

@@ -12,6 +12,7 @@
 #include "../internal.hpp"
 
 #include <absl/container/flat_hash_map.h>
+#include <absl/container/flat_hash_set.h>
 #include <tracy/Tracy.hpp>
 
 #include <algorithm>
@@ -2210,6 +2211,11 @@ struct CachedPipelineState {
   mutable gfx::PipelineRef stereoRef = 0;
   mutable gfx::PipelineRef screenRef = 0;
   mutable gfx::PipelineRef stereoScreenRef = 0;
+  // Constant-alpha siblings, while ref is in s_compositeSourcePipelines. Checked again only when
+  // compositeSourceGeneration falls behind that set (resolve_composite_source_pipelines).
+  mutable gfx::PipelineRef compositeSourceRef = 0;
+  mutable gfx::PipelineRef stereoCompositeSourceRef = 0;
+  mutable u32 compositeSourceGeneration = 0;
   HashType configHash = 0;
   // Carried here so the draw can be recorded without keeping the PipelineConfig that produced it alive; it is the only
   // field of the config the draw itself still needs.
@@ -2278,47 +2284,45 @@ static const CachedPipelineState& resolve_pipeline_state(GXPrimitive prim, GXVtx
   return state;
 }
 
+// The pipelines an eye re-issues at a composite (gfx::link_composite_source). Only the draw
+// paths touch it, under the renderer lock they hold.
+static absl::flat_hash_set<gfx::PipelineRef> s_compositeSourcePipelines;
+// Advanced whenever that set changes, so each cached pipeline state checks its membership once.
+static u32 s_compositeSourceGeneration = 1;
+constexpr size_t kMaxCompositeSourcePipelines = 1024;
+
+static void note_composite_source_pipeline_impl(gfx::PipelineRef pipeline) noexcept {
+  if (s_compositeSourcePipelines.size() >= kMaxCompositeSourcePipelines) {
+    s_compositeSourcePipelines.clear();
+  }
+  if (s_compositeSourcePipelines.insert(pipeline).second && ++s_compositeSourceGeneration == 0) {
+    s_compositeSourceGeneration = 1;
+  }
+}
+
+// A perspective draw pays one compare here. Its pipeline state builds the constant-alpha siblings
+// from its own config, which is live now, once it is in the set; the config never has to be kept.
+static void resolve_composite_source_pipelines(const CachedPipelineState& state) {
+  if (state.compositeSourceGeneration == s_compositeSourceGeneration)
+    LIKELY { return; }
+  state.compositeSourceGeneration = s_compositeSourceGeneration;
+  if (!s_compositeSourcePipelines.contains(state.ref)) {
+    state.compositeSourceRef = 0;
+    state.stereoCompositeSourceRef = 0;
+    return;
+  }
+  if (state.compositeSourceRef == 0) {
+    PipelineConfig config = *state.config;
+    config.stereoStencil = kCompositeSourceBlend;
+    state.compositeSourceRef = gfx::pipeline_ref(config);
+    config.stereoStencil = kCompositeSourceBlend | kStereoStencilFormat;
+    state.stereoCompositeSourceRef = gfx::pipeline_ref(config);
+  }
+}
+
 // Lazily cache eye-format siblings alongside the ordinary pipeline. Steady-state
 // draws only read the refs: no extra config population/hashing on the Quest CPU.
 // Shader modules are shared by the depth-format variants.
-// The configs of the perspective draws recorded while a stereo frame provider is active, so a
-// pass found later to be a composite's source (link_composite_sources) can have constant-alpha
-// siblings built for exactly its draws. Nothing is compiled here; cached_pipeline_state's slot
-// can be overwritten by the time the frame is sealed, which is why the config is kept by value.
-struct CompositeSourceConfig {
-  PipelineConfig config{};
-  gfx::PipelineRef plain = 0;
-  gfx::PipelineRef stencil = 0;
-};
-static absl::flat_hash_map<HashType, CompositeSourceConfig> s_compositeSourceConfigs;
-static std::mutex s_compositeSourceConfigsMutex;
-constexpr size_t kMaxCompositeSourceConfigs = 4096;
-
-static void remember_composite_source_config(const CachedPipelineState& state) {
-  std::lock_guard lock{s_compositeSourceConfigsMutex};
-  if (s_compositeSourceConfigs.contains(state.configHash)) return;
-  if (s_compositeSourceConfigs.size() >= kMaxCompositeSourceConfigs) s_compositeSourceConfigs.clear();
-  s_compositeSourceConfigs.emplace(state.configHash, CompositeSourceConfig{.config = *state.config});
-}
-
-static bool resolve_composite_source_pipelines_impl(HashType configHash, gfx::PipelineRef& plain,
-                                                    gfx::PipelineRef& stencil) {
-  std::lock_guard lock{s_compositeSourceConfigsMutex};
-  const auto it = s_compositeSourceConfigs.find(configHash);
-  if (it == s_compositeSourceConfigs.end()) return false;
-  auto& entry = it->second;
-  if (entry.plain == 0) {
-    PipelineConfig config = entry.config;
-    config.stereoStencil = kCompositeSourceBlend;
-    entry.plain = gfx::pipeline_ref(config);
-    config.stereoStencil = kCompositeSourceBlend | kStereoStencilFormat;
-    entry.stencil = gfx::pipeline_ref(config);
-  }
-  plain = entry.plain;
-  stencil = entry.stencil;
-  return true;
-}
-
 static void resolve_replay_pipelines(const CachedPipelineState& state, bool screen) {
   if (state.stereoRef && (!screen || state.stereoScreenRef)) return;
   PipelineConfig config = *state.config;
@@ -2537,7 +2541,7 @@ static void handle_draw_unmerged(GXPrimitive prim, GXVtxFmt fmt, u16 vtxCount, g
   const bool stereo = aurora::stereo_frame_provider_active();
   const bool screen = !replayLayout.perspective && !replayLayout.nativeEfbEffect;
   if (stereo) resolve_replay_pipelines(pipelineState, screen);
-  if (stereo && replayLayout.perspective) remember_composite_source_config(pipelineState);
+  if (stereo && replayLayout.perspective) resolve_composite_source_pipelines(pipelineState);
   s_lastDrawRecordedInterpolation = interpolationIdentityActive;
 
   uint32_t instanceCount = 1;
@@ -2553,6 +2557,9 @@ static void handle_draw_unmerged(GXPrimitive prim, GXVtxFmt fmt, u16 vtxCount, g
       .exactScreenDepthPipeline = stereo && screen ? pipelineState.screenRef : 0,
       .stereoPipeline = stereo ? pipelineState.stereoRef : 0,
       .stereoScreenPipeline = stereo && screen ? pipelineState.stereoScreenRef : 0,
+      .compositeSourcePipeline = stereo && replayLayout.perspective ? pipelineState.compositeSourceRef : 0,
+      .stereoCompositeSourcePipeline =
+          stereo && replayLayout.perspective ? pipelineState.stereoCompositeSourceRef : 0,
       .vertRange = vertRange,
       .idxRange = idxRange,
       .uniformRange = uniformRanges.current,
@@ -2560,7 +2567,6 @@ static void handle_draw_unmerged(GXPrimitive prim, GXVtxFmt fmt, u16 vtxCount, g
       .stereoUniformRanges = {},
       .previousUniformRange = uniformRanges.previous,
       .uniformReplayLayout = uniformRanges.replayLayout,
-      .configHash = pipelineState.configHash,
       .vtxCount = vtxCount,
       .indexCount = numIndices,
       .instanceCount = instanceCount,
@@ -2738,7 +2744,6 @@ bool handle_aurora(const u8* data, u32& pos, u32 size, bool bigEndian) {
 
 } // namespace aurora::gx::fifo
 
-bool aurora::gx::resolve_composite_source_pipelines(HashType configHash, gfx::PipelineRef& plain,
-                                                    gfx::PipelineRef& stencil) {
-  return fifo::resolve_composite_source_pipelines_impl(configHash, plain, stencil);
+void aurora::gx::note_composite_source_pipeline(gfx::PipelineRef pipeline) noexcept {
+  fifo::note_composite_source_pipeline_impl(pipeline);
 }

aurora-main/lib/gx/pipeline.hpp

@@ -14,11 +14,11 @@ struct DrawData {
   // Eye depth/stencil format siblings. Shader modules are shared with mono.
   gfx::PipelineRef stereoPipeline = 0;
   gfx::PipelineRef stereoScreenPipeline = 0;
-  // Constant-alpha siblings, resolved only for the draws of a composite's source pass
-  // (link_composite_sources) from the config remembered under configHash.
-  gfx::PipelineRef stereoGhostPipeline = 0;
-  gfx::PipelineRef stereoGhostStencilPipeline = 0;
-  HashType configHash = 0;
+  // Constant-alpha (kCompositeSourceBlend) siblings of pipeline and stereoPipeline, set only
+  // on the perspective draws of a pipeline an eye re-issues at a composite
+  // (note_composite_source_pipeline).
+  gfx::PipelineRef compositeSourcePipeline = 0;
+  gfx::PipelineRef stereoCompositeSourcePipeline = 0;
   gfx::Range vertRange;
   gfx::Range idxRange;
   gfx::Range uniformRange;
@@ -101,9 +101,10 @@ void render(const DrawData& data, const wgpu::RenderPassEncoder& pass, DrawEncod
             bool requireReadyPipeline, const gfx::Range* uniformRangeOverride = nullptr,
             gfx::PipelineRef pipelineOverride = 0, const wgpu::Color* blendConstantOverride = nullptr);
 
-// The constant-alpha (kCompositeSourceBlend) siblings of the pipeline recorded under configHash,
-// for a stencil-less and a stencil eye target. False when the config is no longer remembered.
-bool resolve_composite_source_pipelines(HashType configHash, gfx::PipelineRef& plain, gfx::PipelineRef& stencil);
+// Gives the draws of `pipeline` their constant-alpha siblings from its next draw on: an eye
+// re-issues them at a composite (gfx::link_composite_source). Called with the renderer lock
+// the draw paths hold, as the composite is recorded.
+void note_composite_source_pipeline(gfx::PipelineRef pipeline) noexcept;
 
 void queue_surface(const u8* dlStart, uint32_t dlSize, bool bigEndian) noexcept;
 } // namespace aurora::gx

aurora-main/lib/gx/shader_info.hpp

@@ -21,13 +21,10 @@ struct UniformReplayLayout {
   // For a native effect that samples a freshly produced, frame-sized depth copy: that
   // copy. Mario Kart Wii draws a ghost kart alone into the cleared EFB, copies the
   // frame's colour and depth out, draws the race, then blends the copies back with one
-  // such quad. Set when the draw is recorded; the pass that produced the copy holds the
-  // ghost's own perspective draws.
+  // such quad. The pass that resolved the copy holds the ghost's own perspective draws,
+  // which an eye re-issues in this quad's place (gfx::link_composite_source) instead of
+  // stamping the desktop's flat image of the ghost over its own view.
   const gfx::TextureRef* compositeDepthCopy = nullptr;
-  // Index of that pass once the frame is sealed (link_composite_sources), or -1. An eye
-  // re-issues its perspective draws in this composite's place instead of stamping the
-  // desktop's flat image of the ghost over its own view.
-  int32_t compositeSourcePass = -1;
 };
 
 struct UniformRanges {

aurora-main/tests/gx_fifo_test.cpp

@@ -5308,7 +5308,6 @@ TEST_F(GXFifoTest, NativeCompositeRecordsTheFrameSizedDepthCopyItSamples) {
                                                    aurora::gx::FrameInterpolationDrawIdentity{}, false);
   EXPECT_TRUE(composite.replayLayout.nativeEfbEffect);
   EXPECT_EQ(composite.replayLayout.compositeDepthCopy, records[0].texture.get());
-  EXPECT_EQ(composite.replayLayout.compositeSourcePass, -1);
 
   // The same draw with the game camera is world geometry, whatever it samples.
   aurora::gfx::testing::reset_uniform_allocations();
@@ -5316,3 +5315,85 @@ TEST_F(GXFifoTest, NativeCompositeRecordsTheFrameSizedDepthCopyItSamples) {
                                                aurora::gx::FrameInterpolationDrawIdentity{}, true);
   EXPECT_EQ(world.replayLayout.compositeDepthCopy, nullptr);
 }
+
+static void draw_quad_with_projection(GXProjectionType type) {
+  aurora::gfx::testing::use_real_vertex_format_helpers(true);
+  aurora::gfx::testing::use_draw_command_tracking(true);
+
+  aurora::Mat4x4<float> proj{};
+  if (type == GX_PERSPECTIVE) {
+    proj.m0[0] = 1.0f;
+    proj.m1[1] = 1.0f;
+    proj.m2[2] = -1.0f;
+    proj.m2[3] = -1.0f;
+    proj.m3[2] = -1.0f;
+  } else {
+    proj.m0[0] = 2.0f / 608.0f;
+    proj.m0[3] = -1.0f;
+    proj.m1[1] = -2.0f / 456.0f;
+    proj.m1[3] = 1.0f;
+    proj.m2[2] = -1.0f;
+    proj.m3[3] = 1.0f;
+  }
+  GXSetProjection(&proj, type);
+  GXSetViewport(0.0f, 0.0f, 608.0f, 456.0f, 0.0f, 1.0f);
+  GXSetScissor(0, 0, 608, 456);
+  aurora::Mat3x4<float> identity{};
+  identity.m0[0] = identity.m1[1] = identity.m2[2] = 1.0f;
+  GXLoadPosMtxImm(&identity, GX_PNMTX0);
+  GXSetCurrentMtx(GX_PNMTX0);
+
+  GXClearVtxDesc();
+  GXSetVtxDesc(GX_VA_POS, GX_DIRECT);
+  GXSetVtxAttrFmt(GX_VTXFMT0, GX_VA_POS, GX_POS_XYZ, GX_F32, 0);
+  GXSetNumChans(0);
+  GXSetNumTexGens(0);
+  GXSetNumTevStages(1);
+  GXSetTevOrder(GX_TEVSTAGE0, GX_TEXCOORD_NULL, GX_TEXMAP_NULL, GX_COLOR_NULL);
+  GXSetTevColorIn(GX_TEVSTAGE0, GX_CC_ZERO, GX_CC_ZERO, GX_CC_ZERO, GX_CC_C0);
+  GXSetTevColorOp(GX_TEVSTAGE0, GX_TEV_ADD, GX_TB_ZERO, GX_CS_SCALE_1, GX_TRUE, GX_TEVPREV);
+  GXSetTevAlphaIn(GX_TEVSTAGE0, GX_CA_ZERO, GX_CA_ZERO, GX_CA_ZERO, GX_CA_A0);
+  GXSetTevAlphaOp(GX_TEVSTAGE0, GX_TEV_ADD, GX_TB_ZERO, GX_CS_SCALE_1, GX_TRUE, GX_TEVPREV);
+
+  const float corners[4][2]{{-1.0f, -1.0f}, {1.0f, -1.0f}, {1.0f, 1.0f}, {-1.0f, 1.0f}};
+  GXBegin(GX_QUADS, GX_VTXFMT0, 4);
+  for (const auto& corner : corners) {
+    GXPosition3f32(corner[0], corner[1], -5.0f);
+  }
+  GXEnd();
+}
+
+TEST_F(GXFifoTest, CompositeSourcePipelineGetsConstantAlphaSiblingsFromItsNextDraw) {
+  // An eye re-issues MKW's ghost kart draws at the composite with constant-alpha siblings of
+  // their pipelines. Only a pipeline an eye asked for gets them, from its next draw on, and
+  // only in perspective draws.
+  draw_quad_with_projection(GX_PERSPECTIVE);
+  decode_fifo(flush_and_capture());
+  const auto* first = aurora::gfx::get_last_draw_command<aurora::gx::DrawData>();
+  ASSERT_NE(first, nullptr);
+  ASSERT_TRUE(first->uniformReplayLayout.perspective);
+  ASSERT_NE(first->pipeline, 0u);
+  EXPECT_EQ(first->compositeSourcePipeline, 0u);
+  EXPECT_EQ(first->stereoCompositeSourcePipeline, 0u);
+  const auto pipeline = first->pipeline;
+
+  aurora::gx::note_composite_source_pipeline(pipeline);
+  draw_quad_with_projection(GX_PERSPECTIVE);
+  decode_fifo(flush_and_capture());
+  const auto* next = aurora::gfx::get_last_draw_command<aurora::gx::DrawData>();
+  ASSERT_NE(next, nullptr);
+  ASSERT_EQ(next->pipeline, pipeline);
+  EXPECT_NE(next->compositeSourcePipeline, 0u);
+  EXPECT_NE(next->stereoCompositeSourcePipeline, 0u);
+  EXPECT_NE(next->compositeSourcePipeline, next->pipeline);
+  EXPECT_NE(next->stereoCompositeSourcePipeline, next->stereoPipeline);
+  EXPECT_NE(next->compositeSourcePipeline, next->stereoCompositeSourcePipeline);
+
+  draw_quad_with_projection(GX_ORTHOGRAPHIC);
+  decode_fifo(flush_and_capture());
+  const auto* flat = aurora::gfx::get_last_draw_command<aurora::gx::DrawData>();
+  ASSERT_NE(flat, nullptr);
+  ASSERT_EQ(flat->pipeline, pipeline);
+  EXPECT_EQ(flat->compositeSourcePipeline, 0u);
+  EXPECT_EQ(flat->stereoCompositeSourcePipeline, 0u);
+}

aurora-main/tests/gx_test_stubs.cpp

@@ -357,7 +357,8 @@ void push_draw_command<clear::DrawData>(clear::DrawData data) {
 }
 template <>
 PipelineRef pipeline_ref<gx::PipelineConfig>(const gx::PipelineConfig& config) {
-  return 0;
+  // Distinct configs get distinct refs, as the real cache's config hash does.
+  return xxh3_hash(config, static_cast<HashType>(ShaderType::GX));
 }
 template <>
 void push_draw_command<gx::DrawData>(gx::DrawData data) {