rhi: Add support for polygon fill mode

Support for Polygon Mode (Triangle Fill Mode in Metal, Fill Mode in D3D)
in the RHI graphics pipeline.

Options are Fill and Line

Status:
    OpenGL - ok
    Vulkan - ok
    Metal - ok
    D3D11 - ok
    OpenGL ES - does not support glPolygonMode.

Change-Id: I20b7ef416624700c3dc8d1cbe6474f4ca3889db8
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/gui/rhi/qrhi_p.h b/src/gui/rhi/qrhi_p.h
index 8c38b6383d..b0cf9e3469 100644
--- a/src/gui/rhi/qrhi_p.h
+++ b/src/gui/rhi/qrhi_p.h
@@ -1223,6 +1223,11 @@ public:
         CompareOp compareOp = Always;
     };
 
+    enum PolygonMode {
+        Fill,
+        Line
+    };
+
     QRhiResource::Type resourceType() const override;
 
     Flags flags() const { return m_flags; }
@@ -1305,6 +1310,9 @@ public:
     int patchControlPointCount() const { return m_patchControlPointCount; }
     void setPatchControlPointCount(int count) { m_patchControlPointCount = count; }
 
+    PolygonMode polygonMode() const {return m_polygonMode; }
+    void setPolygonMode(PolygonMode mode) {m_polygonMode = mode; }
+
     virtual bool create() = 0;
 
 protected:
@@ -1327,6 +1335,7 @@ protected:
     int m_depthBias = 0;
     float m_slopeScaledDepthBias = 0.0f;
     int m_patchControlPointCount = 3;
+    PolygonMode m_polygonMode = Fill;
     QVarLengthArray<QRhiShaderStage, 4> m_shaderStages;
     QRhiVertexInputLayout m_vertexInputLayout;
     QRhiShaderResourceBindings *m_shaderResourceBindings = nullptr;