From 197929d967f587502256fd52c0c5121781fd0e47 Mon Sep 17 00:00:00 2001
From: goldislead <69987043+goldislead@users.noreply.github.com>
Date: Sun, 9 Aug 2026 18:34:00 -0700
Subject: [PATCH] [D3D12] Fall back to point sampling for non-filterable
 formats

Matches Vulkan.

Co-authored-by: Herman S. <429230+has207@users.noreply.github.com>
---
 src/xenia/gpu/d3d12/d3d12_texture_cache.cc | 48 +++++++++++++++++++++-
 src/xenia/gpu/d3d12/d3d12_texture_cache.h  |  4 ++
 2 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/src/xenia/gpu/d3d12/d3d12_texture_cache.cc b/src/xenia/gpu/d3d12/d3d12_texture_cache.cc
index 94d2e038c..998a9a640 100644
--- a/src/xenia/gpu/d3d12/d3d12_texture_cache.cc
+++ b/src/xenia/gpu/d3d12/d3d12_texture_cache.cc
@@ -140,6 +140,32 @@ bool D3D12TextureCache::Initialize() {
   }
   scaled_resolve_heap_count_ = 0;
 
+  // GetSamplerParameters drops samplers for non-filterable formats.
+  for (uint32_t i = 0; i < xe::countof(host_formats_); ++i) {
+    const HostFormat& host_format = host_formats_[i];
+    uint64_t format_bit = uint64_t(1) << i;
+    if (host_format.dxgi_format_unsigned != DXGI_FORMAT_UNKNOWN) {
+      D3D12_FEATURE_DATA_FORMAT_SUPPORT format_support = {
+          host_format.dxgi_format_unsigned};
+      if (SUCCEEDED(device->CheckFeatureSupport(D3D12_FEATURE_FORMAT_SUPPORT,
+                                                &format_support,
+                                                sizeof(format_support))) &&
+          (format_support.Support1 & D3D12_FORMAT_SUPPORT1_SHADER_SAMPLE)) {
+        host_filterable_unsigned_ |= format_bit;
+      }
+    }
+    if (host_format.dxgi_format_signed != DXGI_FORMAT_UNKNOWN) {
+      D3D12_FEATURE_DATA_FORMAT_SUPPORT format_support = {
+          host_format.dxgi_format_signed};
+      if (SUCCEEDED(device->CheckFeatureSupport(D3D12_FEATURE_FORMAT_SUPPORT,
+                                                &format_support,
+                                                sizeof(format_support))) &&
+          (format_support.Support1 & D3D12_FORMAT_SUPPORT1_SHADER_SAMPLE)) {
+        host_filterable_signed_ |= format_bit;
+      }
+    }
+  }
+
   // Create the loading root signature.
   D3D12_ROOT_PARAMETER root_parameters[3];
   // Parameter 0 is constants (changed multiple times when untiling).
@@ -795,7 +821,6 @@ D3D12TextureCache::SamplerParameters D3D12TextureCache::GetSamplerParameters(
       mip_filter == xenos::TextureFilter::kLinear;
   bool mip_base_map = mip_filter == xenos::TextureFilter::kBaseMap;
   // high cache miss count here, prefetch fetch earlier
-  //  TODO(Triang3l): Disable filtering for texture formats not supporting it.
   xenos::AnisoFilter aniso_filter =
       binding.aniso_filter == xenos::AnisoFilter::kUseFetchConst
           ? fetch.aniso_filter
@@ -820,6 +845,27 @@ D3D12TextureCache::SamplerParameters D3D12TextureCache::GetSamplerParameters(
   }
   parameters.mip_base_map = mip_base_map;
 
+  // Fall back to point sampling if the host formats don't report
+  // D3D12_FORMAT_SUPPORT1_SHADER_SAMPLE.
+  if (parameters.mag_linear || parameters.min_linear || parameters.mip_linear ||
+      parameters.aniso_filter != xenos::AnisoFilter::kDisabled) {
+    TextureKey texture_key;
+    uint8_t texture_swizzled_signs;
+    BindingInfoFromFetchConstant(fetch, texture_key, &texture_swizzled_signs);
+    uint64_t format_bit =
+        texture_key.is_valid ? uint64_t(1) << uint32_t(texture_key.format) : 0;
+    if (!texture_key.is_valid ||
+        (texture_util::IsAnySignNotSigned(texture_swizzled_signs) &&
+         (host_filterable_unsigned_ & format_bit) == 0) ||
+        (texture_util::IsAnySignSigned(texture_swizzled_signs) &&
+         (host_filterable_signed_ & format_bit) == 0)) {
+      parameters.mag_linear = 0;
+      parameters.min_linear = 0;
+      parameters.mip_linear = 0;
+      parameters.aniso_filter = xenos::AnisoFilter::kDisabled;
+    }
+  }
+
   return parameters;
 }
 
diff --git a/src/xenia/gpu/d3d12/d3d12_texture_cache.h b/src/xenia/gpu/d3d12/d3d12_texture_cache.h
index 599d42fb1..4e1c34bd3 100644
--- a/src/xenia/gpu/d3d12/d3d12_texture_cache.h
+++ b/src/xenia/gpu/d3d12/d3d12_texture_cache.h
@@ -821,6 +821,10 @@ class D3D12TextureCache final : public TextureCache {
   D3D12CommandProcessor& command_processor_;
   bool bindless_resources_used_;
 
+  // Bits per format, for checking if the host format should be point-filtered.
+  uint64_t host_filterable_unsigned_ = 0;
+  uint64_t host_filterable_signed_ = 0;
+
   Microsoft::WRL::ComPtr<ID3D12RootSignature> load_root_signature_;
   std::array<Microsoft::WRL::ComPtr<ID3D12PipelineState>, kLoadShaderCount>
       load_pipelines_;