Fix incorrect copy filter clamping

We need to clamp to the center of pixels, or else things end up working out incorrectly.  This also fixes an off-by-1 for the bottom line.

1 files changed, 11 insertions, 4 deletions

diff --git a/Source/Core/VideoCommon/TextureCacheBase.cpp b/Source/Core/VideoCommon/TextureCacheBase.cpp
index efe6a381a0..e651e26746 100644
--- a/Source/Core/VideoCommon/TextureCacheBase.cpp
+++ b/Source/Core/VideoCommon/TextureCacheBase.cpp
@@ -2676,7 +2676,8 @@ void TextureCacheBase::CopyEFBToCacheEntry(TCacheEntry* entry, bool is_depth_cop
   };
   Uniforms uniforms;
   const float rcp_efb_width = 1.0f / static_cast<float>(g_framebuffer_manager->GetEFBWidth());
-  const float rcp_efb_height = 1.0f / static_cast<float>(g_framebuffer_manager->GetEFBHeight());
+  const u32 efb_height = g_framebuffer_manager->GetEFBHeight();
+  const float rcp_efb_height = 1.0f / static_cast<float>(efb_height);
   uniforms.src_left = framebuffer_rect.left * rcp_efb_width;
   uniforms.src_top = framebuffer_rect.top * rcp_efb_height;
   uniforms.src_width = framebuffer_rect.GetWidth() * rcp_efb_width;
@@ -2685,9 +2686,15 @@ void TextureCacheBase::CopyEFBToCacheEntry(TCacheEntry* entry, bool is_depth_cop
   uniforms.filter_coefficients[1] = filter_coefficients.middle;
   uniforms.filter_coefficients[2] = filter_coefficients.lower;
   uniforms.gamma_rcp = 1.0f / gamma;
-  uniforms.clamp_top = clamp_top ? framebuffer_rect.top * rcp_efb_height : 0.0f;
-  int bottom_coord = framebuffer_rect.bottom - 1;
-  uniforms.clamp_bottom = clamp_bottom ? bottom_coord * rcp_efb_height : 1.0f;
+  //   NOTE: when the clamp bits aren't set, the hardware will happily read beyond the EFB,
+  //         which returns random garbage from the empty bus (confirmed by hardware tests).
+  //
+  //         In our implementation, the garbage just so happens to be the top or bottom row.
+  //         Statistically, that could happen.
+  const u32 top_coord = clamp_top ? framebuffer_rect.top : 0;
+  uniforms.clamp_top = (static_cast<float>(top_coord) + .5f) * rcp_efb_height;
+  const u32 bottom_coord = (clamp_bottom ? framebuffer_rect.bottom : efb_height) - 1;
+  uniforms.clamp_bottom = (static_cast<float>(bottom_coord) + .5f) * rcp_efb_height;
   uniforms.pixel_height = g_ActiveConfig.bCopyEFBScaled ? rcp_efb_height : 1.0f / EFB_HEIGHT;
   uniforms.padding = 0;
   g_vertex_manager->UploadUtilityUniforms(&uniforms, sizeof(uniforms));