[GPU] Simplify ZPD cvars

src/xenia/gpu/command_processor.cc

@@ -58,7 +58,10 @@ DEFINE_string(
     "       though some effects may look slightly wrong.\n"
     " fast: Ask the GPU but don't wait for the answer. Writes a cached\n"
     "       result immediately and updates it when the GPU catches up.\n"
-    "       (default)\n"
+    "       Cached results bias toward visible when guessing. (default)\n"
+    " fast-alt: Variant of fast mode that keeps cached zero results for\n"
+    "           unresolved reports. May improve effects relying on precise\n"
+    "           visibility, but may be less stable for occlusion culling.\n"
     " strict: Ask the GPU and wait for the real result before continuing.\n"
     "         Most accurate, but may be somewhat less performant.",
     "GPU");
@@ -130,6 +133,8 @@ ZPDMode GetZPDMode() {
     return ZPDMode::kFake;
   } else if (mode == "strict") {
     return ZPDMode::kStrict;
+  } else if (mode == "fast-alt") {
+    return ZPDMode::kFastAlt;
   }
   return ZPDMode::kFast;
 }
@@ -968,7 +973,7 @@ bool CommandProcessor::BeginZPDReport(uint32_t report_address) {
   PendingZPDSlot pending_slot = GetPendingZPDSlot(slot_base, end_record);
 
   if (pending_slot.report_handle != kInvalidReportHandle) {
-    if (GetZPDMode() == ZPDMode::kFast) {
+    if (GetZPDMode() == ZPDMode::kFast || GetZPDMode() == ZPDMode::kFastAlt) {
       if (pending_slot.has_cached_delta) {
         carried_cached_delta = pending_slot.cached_delta;
         has_carried_cached_delta = true;
@@ -1008,7 +1013,7 @@ bool CommandProcessor::BeginZPDReport(uint32_t report_address) {
   // By default, BEGIN drops the cached value so an orphaned END doesn't replay
   // something from a prior lifetime. The alternate fast path keeps it around
   // long enough for an async zero to help the next unresolved write.
-  if (!cvars::occlusion_query_fast_preserve_cached_zero) {
+  if (GetZPDMode() != ZPDMode::kFastAlt) {
     fast_zpd_report_cached_values_.erase(end_record);
   }
 
@@ -1136,7 +1141,7 @@ bool CommandProcessor::EndZPDReport(uint32_t report_address,
     WriteZPDReport(0, stored_end_record, 0, begin_value, false);
   }
 
-  if (GetZPDMode() == ZPDMode::kFast) {
+  if (GetZPDMode() == ZPDMode::kFast || GetZPDMode() == ZPDMode::kFastAlt) {
     bool write_begin = begin_record && report_record_base &&
                        begin_record != report_record_base;
     // Unknown still means visible in fast mode. Reusing cached zeroes can help
@@ -1147,8 +1152,7 @@ bool CommandProcessor::EndZPDReport(uint32_t report_address,
     if (!resolved_immediately) {
       speculative = 1;
       if (has_cached_delta &&
-          (cached_delta != 0 ||
+          (cached_delta != 0 || GetZPDMode() == ZPDMode::kFastAlt)) {
-           cvars::occlusion_query_fast_preserve_cached_zero)) {
         speculative = cached_delta;
       }
     }
@@ -1201,7 +1205,7 @@ void CommandProcessor::OpenQuerySegment(bool can_close_submission) {
     case QueryOpenResult::kDeferred:
       return;
     case QueryOpenResult::kPoolExhausted: {
-      if (GetZPDMode() == ZPDMode::kFast) {
+      if (GetZPDMode() == ZPDMode::kFast || GetZPDMode() == ZPDMode::kFastAlt) {
         // Fast mode favors forward progress over accuracy. Keep a minimal
         // accumulated value instead of waiting for a slot to become available.
         auto it = logical_zpd_reports_.find(zpd_active_segment_.report_handle);

src/xenia/gpu/command_processor.h

@@ -45,9 +45,10 @@ enum class ReadbackResolveMode {
 
 // Occlusion queries - ZPD report mode.
 enum class ZPDMode {
-  kFake,    // Fake sample counts, no real GPU queries (fake)
+  kFake,     // Fake sample counts, no real GPU queries (fake)
-  kFast,    // Real queries with speculative cached writes (fast)
+  kFast,     // Real queries with speculative cached writes (fast)
-  kStrict,  // Real queries, waits before writeback (strict)
+  kFastAlt,  // Fast queries, but preserves cached zeroes (fast-alt)
+  kStrict,   // Real queries, waits before writeback (strict)
 };
 
 void SaveGPUSetting(GPUSetting setting, uint64_t value);
@@ -324,8 +325,7 @@ class CommandProcessor {
     uint32_t begin_value = 0;
     uint32_t pending_segments = 0;
     // Last known delta. Carried forward on forced close so slot doesn't
-    // briefly look fully occluded. 0 is a valid delta if the alternate fast
+    // briefly look fully occluded. 0 is a valid delta for alternate fast path.
-    // cvar is enabled.
     uint32_t cached_delta = 0;
     bool has_cached_delta = false;
     bool ended = false;

src/xenia/gpu/d3d12/d3d12_command_processor.cc

@@ -5312,7 +5312,7 @@ CommandProcessor::QueryOpenResult D3D12CommandProcessor::OpenZPDQuery(
   bool waited_for_submission = false;
 
   if (is_pool_exhausted) {
-    if (GetZPDMode() == ZPDMode::kFast) {
+    if (GetZPDMode() == ZPDMode::kFast || GetZPDMode() == ZPDMode::kFastAlt) {
       return QueryOpenResult::kPoolExhausted;
     }
 

src/xenia/gpu/gpu_flags.cc

@@ -71,13 +71,6 @@ DEFINE_int32(occlusion_query_fake_upper_threshold, 100,
              "Keep this higher than occlusion_query_fake_lower_threshold.\n"
              "Ignored if occlusion_query_fake_lower_threshold is -1.",
              "GPU");
-DEFINE_bool(occlusion_query_fast_preserve_cached_zero, false,
-            "Alternate fast ZPD behavior that allows saved zero results to be "
-            "used for unresolved fast writes instead of forcing them visible.\n"
-            "This can materially improve flare accuracy in titles that might "
-            "otherwise need strict mode, but it also tends to break occlusion "
-            "culling in some titles.",
-            "GPU");
 DEFINE_int32(occlusion_query_querybatch_range, 0,
              "Range of fake sample count values to walk for titles using the "
              "D3D QueryBatch standard before wrapping back to "
@@ -86,7 +79,7 @@ DEFINE_int32(occlusion_query_querybatch_range, 0,
              "unless necessary for a specific title.",
              "GPU");
 DEFINE_double(
-    occlusion_query_sample_count_saturation, 1.0,
+    occlusion_query_saturation, 1.0,
     "Compress higher occlusion query sample counts before guest writeback.\n"
     "This can be useful if effects such as lens flares appear too strong.\n"
     "1.0 = default behavior\n"

src/xenia/gpu/gpu_flags.h

@@ -32,11 +32,9 @@ DECLARE_int32(occlusion_query_fake_lower_threshold);
 
 DECLARE_int32(occlusion_query_fake_upper_threshold);
 
-DECLARE_bool(occlusion_query_fast_preserve_cached_zero);
-
 DECLARE_int32(occlusion_query_querybatch_range);
 
-DECLARE_double(occlusion_query_sample_count_saturation);
+DECLARE_double(occlusion_query_saturation);
 
 DECLARE_int32(anisotropic_override);
 

src/xenia/gpu/pm4_command_processor_implement.h

@@ -1011,7 +1011,7 @@ bool COMMAND_PROCESSOR::ExecutePacketType3_EVENT_WRITE_ZPD(
       // No logical report is active for this slot, so this is likely an
       // orphaned END. In fast mode, replay the last cached delta so polling
       // code does not sit on the sentinel forever.
-      if (GetZPDMode() == ZPDMode::kFast) {
+      if (GetZPDMode() == ZPDMode::kFast || GetZPDMode() == ZPDMode::kFastAlt) {
         uint32_t cached_delta = 1;
         auto cache_it = fast_zpd_report_cached_values_.find(report_record_base);
         if (cache_it != fast_zpd_report_cached_values_.end()) {

src/xenia/gpu/vulkan/vulkan_command_processor.cc

@@ -3318,7 +3318,8 @@ CommandProcessor::QueryOpenResult VulkanCommandProcessor::OpenZPDQuery(
       is_pool_exhausted = !zpd_host_query_pool_->has_free_indices();
     }
 
-    if (is_pool_exhausted && GetZPDMode() == ZPDMode::kFast) {
+    if (is_pool_exhausted &&
+        (GetZPDMode() == ZPDMode::kFast || GetZPDMode() == ZPDMode::kFastAlt)) {
       return QueryOpenResult::kPoolExhausted;
     }
 

src/xenia/gpu/xenos_zpd_report.h

@@ -102,8 +102,7 @@ struct XenosZPDReport {
 
   static uint32_t SaturateSampleCount(uint32_t sample_count) {
     double saturation = std::clamp(
-        static_cast<double>(cvars::occlusion_query_sample_count_saturation),
+        static_cast<double>(cvars::occlusion_query_saturation), 0.0, 1.0);
-        0.0, 1.0);
 
     if (sample_count == 0 || saturation >= 1.0) {
       return sample_count;