OGL: Handle cases where reversed depth is already used.

1 files changed, 20 insertions, 2 deletions

diff --git a/Source/Core/VideoCommon/VertexShaderManager.cpp b/Source/Core/VideoCommon/VertexShaderManager.cpp
index 5f9f4affdc..e8f82d0bf5 100644
--- a/Source/Core/VideoCommon/VertexShaderManager.cpp
+++ b/Source/Core/VideoCommon/VertexShaderManager.cpp
@@ -392,8 +392,26 @@ void VertexShaderManager::SetConstants()
     // 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.
-    constants.pixelcentercorrection[2] = xfmem.viewport.zRange / 16777215.0f;
-    constants.pixelcentercorrection[3] = 1.0f - xfmem.viewport.farZ / 16777215.0f;
+    if (g_ActiveConfig.backend_info.bSupportsReversedDepthRange)
+    {
+      // 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] = abs(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
+    {
+      // 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;
+    }
 
     dirty = true;
     // This is so implementation-dependent that we can't have it here.