Merge pull request #4935 from Armada651/depth-range-fix

VideoBackends: Set the maximum range when the depth range is oversized.

5 files changed, 48 insertions, 26 deletions

diff --git a/Source/Core/VideoCommon/BPStructs.cpp b/Source/Core/VideoCommon/BPStructs.cpp
index 8384080099..774754839b 100644
--- a/Source/Core/VideoCommon/BPStructs.cpp
+++ b/Source/Core/VideoCommon/BPStructs.cpp
@@ -332,6 +332,8 @@ static void BPWritten(const BPCmd& bp)
   {
     if (bp.changes & 3)
       PixelShaderManager::SetZTextureTypeChanged();
+    if (bp.changes & 12)
+      VertexShaderManager::SetViewportChanged();
 #if defined(_DEBUG) || defined(DEBUGFAST)
     const char* pzop[] = {"DISABLE", "ADD", "REPLACE", "?"};
     const char* pztype[] = {"Z8", "Z16", "Z24", "?"};
diff --git a/Source/Core/VideoCommon/RenderBase.cpp b/Source/Core/VideoCommon/RenderBase.cpp
index 1c99e51950..87b3a5314a 100644
--- a/Source/Core/VideoCommon/RenderBase.cpp
+++ b/Source/Core/VideoCommon/RenderBase.cpp
@@ -926,3 +926,32 @@ void Renderer::DumpFrameToImage(const FrameDumpConfig& config)
   TextureToPng(config.data, config.stride, filename, config.width, config.height, false);
   m_frame_dump_image_counter++;
 }
+
+bool Renderer::UseVertexDepthRange() const
+{
+  // We can't compute the depth range in the vertex shader if we don't support depth clamp.
+  if (!g_ActiveConfig.backend_info.bSupportsDepthClamp)
+    return false;
+
+  const bool ztexture_enabled = bpmem.ztex2.type != ZTEXTURE_DISABLE && !bpmem.zcontrol.early_ztest;
+
+  if (g_ActiveConfig.backend_info.bSupportsOversizedDepthRanges)
+  {
+    // We support oversized depth ranges, but we need a full depth range if a ztexture is used.
+    return ztexture_enabled;
+  }
+  else
+  {
+    // We need a full depth range if a ztexture is used.
+    if (ztexture_enabled)
+      return true;
+
+    // If an inverted depth range is unsupported, we also need to check if the range is inverted.
+    if (!g_ActiveConfig.backend_info.bSupportsReversedDepthRange && xfmem.viewport.zRange < 0.0f)
+      return true;
+
+    // If an oversized depth range or a ztexture is used, we need to calculate the depth range
+    // in the vertex shader.
+    return fabs(xfmem.viewport.zRange) > 16777215.0f || fabs(xfmem.viewport.farZ) > 16777215.0f;
+  }
+}
diff --git a/Source/Core/VideoCommon/RenderBase.h b/Source/Core/VideoCommon/RenderBase.h
index b1291adf0d..93c22f6202 100644
--- a/Source/Core/VideoCommon/RenderBase.h
+++ b/Source/Core/VideoCommon/RenderBase.h
@@ -140,6 +140,8 @@ public:
   // Final surface changing
   // This is called when the surface is resized (WX) or the window changes (Android).
   virtual void ChangeSurface(void* new_surface_handle) {}
+  bool UseVertexDepthRange() const;
+
 protected:
   void CalculateTargetScale(int x, int y, int* scaledX, int* scaledY);
   bool CalculateTargetSize();
diff --git a/Source/Core/VideoCommon/VertexShaderManager.cpp b/Source/Core/VideoCommon/VertexShaderManager.cpp
index 4c3959d92d..36bace7426 100644
--- a/Source/Core/VideoCommon/VertexShaderManager.cpp
+++ b/Source/Core/VideoCommon/VertexShaderManager.cpp
@@ -391,39 +391,27 @@ void VertexShaderManager::SetConstants()
     constants.pixelcentercorrection[2] = 1.0f;
     constants.pixelcentercorrection[3] = 0.0f;
 
-    if (g_ActiveConfig.backend_info.bSupportsDepthClamp)
+    if (g_renderer->UseVertexDepthRange())
     {
       // Oversized depth ranges are handled in the vertex shader. We need to reverse
-      // the far value to get a reversed depth range mapping. This is necessary
-      // because the standard depth range equation pushes all depth values towards
-      // the back of the depth buffer where conventionally depth buffers have the
-      // least precision.
+      // the far value to use the reversed-Z trick.
       if (g_ActiveConfig.backend_info.bSupportsReversedDepthRange)
       {
-        if (fabs(xfmem.viewport.zRange) > 16777215.0f || fabs(xfmem.viewport.farZ) > 16777215.0f)
-        {
-          // For backends that support reversing the depth range we also support cases
-          // where the console also uses reversed depth with the same accuracy. We need
-          // to make sure the depth range is positive here and then reverse the depth in
-          // the backend viewport.
-          constants.pixelcentercorrection[2] = fabs(xfmem.viewport.zRange) / 16777215.0f;
-          if (xfmem.viewport.zRange < 0.0f)
-            constants.pixelcentercorrection[3] = xfmem.viewport.farZ / 16777215.0f;
-          else
-            constants.pixelcentercorrection[3] = 1.0f - xfmem.viewport.farZ / 16777215.0f;
-        }
+        // Sometimes the console also tries to use the reversed-Z trick. We can only do
+        // that with the expected accuracy if the backend can reverse the depth range.
+        constants.pixelcentercorrection[2] = fabs(xfmem.viewport.zRange) / 16777215.0f;
+        if (xfmem.viewport.zRange < 0.0f)
+          constants.pixelcentercorrection[3] = xfmem.viewport.farZ / 16777215.0f;
+        else
+          constants.pixelcentercorrection[3] = 1.0f - xfmem.viewport.farZ / 16777215.0f;
       }
       else
       {
-        if (xfmem.viewport.zRange < 0.0f || xfmem.viewport.zRange > 16777215.0f ||
-            fabs(xfmem.viewport.farZ) > 16777215.0f)
-        {
-          // For backends that don't support reversing the depth range we can still render
-          // cases where the console uses reversed depth correctly. But we simply can't
-          // provide the same accuracy as the console.
-          constants.pixelcentercorrection[2] = xfmem.viewport.zRange / 16777215.0f;
-          constants.pixelcentercorrection[3] = 1.0f - xfmem.viewport.farZ / 16777215.0f;
-        }
+        // For backends that don't support reversing the depth range we can still render
+        // cases where the console uses the reversed-Z trick. But we simply can't provide
+        // the expected accuracy, which might result in z-fighting.
+        constants.pixelcentercorrection[2] = xfmem.viewport.zRange / 16777215.0f;
+        constants.pixelcentercorrection[3] = 1.0f - xfmem.viewport.farZ / 16777215.0f;
       }
     }
 
diff --git a/Source/Core/VideoCommon/VideoConfig.h b/Source/Core/VideoCommon/VideoConfig.h
index ec79e6de48..d62334df8e 100644
--- a/Source/Core/VideoCommon/VideoConfig.h
+++ b/Source/Core/VideoCommon/VideoConfig.h
@@ -179,6 +179,7 @@ struct VideoConfig final
     bool bSupportsDualSourceBlend;
     bool bSupportsPrimitiveRestart;
     bool bSupportsOversizedViewports;
+    bool bSupportsOversizedDepthRanges;
     bool bSupportsGeometryShaders;
     bool bSupports3DVision;
     bool bSupportsEarlyZ;         // needed by PixelShaderGen, so must stay in VideoCommon