VideoBackends: Use vertex shader depth range if ztexture is used.

1 files changed, 27 insertions, 0 deletions

diff --git a/Source/Core/VideoCommon/RenderBase.cpp b/Source/Core/VideoCommon/RenderBase.cpp
index f47288ea4e..19ec2abed2 100644
--- a/Source/Core/VideoCommon/RenderBase.cpp
+++ b/Source/Core/VideoCommon/RenderBase.cpp
@@ -940,3 +940,30 @@ 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;
+
+  if (g_ActiveConfig.backend_info.bSupportsOversizedDepthRanges)
+  {
+    // We support oversized depth ranges, but we need a full depth range if a ztexture is used.
+    return bpmem.ztex2.type != ZTEXTURE_DISABLE;
+  }
+  else
+  {
+    // We need a full depth range if a ztexture is used.
+    if (bpmem.ztex2.type != ZTEXTURE_DISABLE)
+      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;
+  }
+}