Fix depth clamp enable bit, unit scale for polygon offset. (#1178)

Verified with deko3d and opengl driver code.

Ryujinx.Graphics.GAL/IPipeline.cs

@@ -27,7 +27,7 @@ namespace Ryujinx.Graphics.GAL
         void SetBlendState(int index, BlendDescriptor blend);
 
         void SetDepthBias(PolygonModeMask enables, float factor, float units, float clamp);
-        void SetDepthClamp(bool clampNear, bool clampFar);
+        void SetDepthClamp(bool clamp);
         void SetDepthMode(DepthMode mode);
         void SetDepthTest(DepthTestDescriptor depthTest);
 

Ryujinx.Graphics.Gpu/Engine/Methods.cs

@@ -394,8 +394,7 @@ namespace Ryujinx.Graphics.Gpu.Engine
         private void UpdateDepthClampState(GpuState state)
         {
             ViewVolumeClipControl clip = state.Get<ViewVolumeClipControl>(MethodOffset.ViewVolumeClipControl);
-            _context.Renderer.Pipeline.SetDepthClamp((clip & ViewVolumeClipControl.DepthClampNear) != 0,
-                                                     (clip & ViewVolumeClipControl.DepthClampFar) != 0);
+            _context.Renderer.Pipeline.SetDepthClamp((clip & ViewVolumeClipControl.DepthClampDisabled) == 0);
         }
 
         /// <summary>

Ryujinx.Graphics.Gpu/State/ViewVolumeClipControl.cs

@@ -6,7 +6,6 @@ namespace Ryujinx.Graphics.Gpu.State
     enum ViewVolumeClipControl
     {
         ForceDepthRangeZeroToOne = 1 << 0,
-        DepthClampNear           = 1 << 3,
-        DepthClampFar            = 1 << 4,
+        DepthClampDisabled       = 1 << 11,
     }
 }

Ryujinx.Graphics.OpenGL/Pipeline.cs

@@ -549,17 +549,13 @@ namespace Ryujinx.Graphics.OpenGL
                 return;
             }
 
-            GL.PolygonOffset(factor, units);
+            GL.PolygonOffset(factor, units / 2f);
             // TODO: Enable when GL_EXT_polygon_offset_clamp is supported.
             // GL.PolygonOffsetClamp(factor, units, clamp);
         }
 
-        public void SetDepthClamp(bool clampNear, bool clampFar)
+        public void SetDepthClamp(bool clamp)
         {
-            // TODO: Use GL_AMD_depth_clamp_separate or similar if available?
-            // Currently enables clamping if either is set.
-            bool clamp = clampNear || clampFar;
-
             if (!clamp)
             {
                 GL.Disable(EnableCap.DepthClamp);