VideoBackends: Use the full depth range when inverted depth range is unsupported.

Source/Core/VideoBackends/D3D12/Render.cpp

@@ -478,10 +478,13 @@ void Renderer::SetViewport()
     y += height;
     height = -height;
   }
+
+  // If an inverted depth range is used, which D3D doesn't support,
+  // we need to calculate the depth range in the vertex shader.
   if (xfmem.viewport.zRange < 0.0f)
   {
-    min_depth = 1.0f - min_depth;
-    max_depth = 1.0f - max_depth;
+    min_depth = 0.0f;
+    max_depth = GX_MAX_DEPTH;
   }
 
   // In D3D, the viewport rectangle must fit within the render target.
@@ -490,11 +493,9 @@ void Renderer::SetViewport()
   width = (x + width <= GetTargetWidth()) ? width : (GetTargetWidth() - x);
   height = (y + height <= GetTargetHeight()) ? height : (GetTargetHeight() - y);
 
-  // We do depth clipping and depth range in the vertex shader instead of relying
-  // on the graphics API. However we still need to ensure depth values don't exceed
-  // the maximum value supported by the console GPU. We also need to account for the
-  // fact that the entire depth buffer is inverted on D3D, so we set GX_MAX_DEPTH as
-  // an inverted near value.
+  // We use an inverted depth range here to apply the Reverse Z trick.
+  // This trick makes sure we match the precision provided by the 1:0
+  // clipping depth range on the hardware.
   D3D12_VIEWPORT vp = {x, y, width, height, 1.0f - max_depth, 1.0f - min_depth};
   D3D::current_command_list->RSSetViewports(1, &vp);
 }