2 files changed, 19 insertions, 3 deletions

diff --git a/src/video_core/primitive_assembly.cpp b/src/video_core/primitive_assembly.cpp
index acd2ac5e2..9c3dd4cab 100644
--- a/src/video_core/primitive_assembly.cpp
+++ b/src/video_core/primitive_assembly.cpp
@@ -17,15 +17,18 @@ template <typename VertexType>
 void PrimitiveAssembler<VertexType>::SubmitVertex(const VertexType& vtx,
                                                   TriangleHandler triangle_handler) {
     switch (topology) {
-    // TODO: Figure out what's different with TriangleTopology::Shader.
     case PipelineRegs::TriangleTopology::List:
     case PipelineRegs::TriangleTopology::Shader:
         if (buffer_index < 2) {
             buffer[buffer_index++] = vtx;
         } else {
             buffer_index = 0;
-
-            triangle_handler(buffer[0], buffer[1], vtx);
+            if (topology == PipelineRegs::TriangleTopology::Shader && winding) {
+                triangle_handler(buffer[1], buffer[0], vtx);
+                winding = false;
+            } else {
+                triangle_handler(buffer[0], buffer[1], vtx);
+            }
         }
         break;
 
@@ -51,9 +54,15 @@ void PrimitiveAssembler<VertexType>::SubmitVertex(const VertexType& vtx,
 }
 
 template <typename VertexType>
+void PrimitiveAssembler<VertexType>::SetWinding() {
+    winding = true;
+}
+
+template <typename VertexType>
 void PrimitiveAssembler<VertexType>::Reset() {
     buffer_index = 0;
     strip_ready = false;
+    winding = false;
 }
 
 template <typename VertexType>
diff --git a/src/video_core/primitive_assembly.h b/src/video_core/primitive_assembly.h
index e8eccdf27..12de8e3b9 100644
--- a/src/video_core/primitive_assembly.h
+++ b/src/video_core/primitive_assembly.h
@@ -30,6 +30,12 @@ struct PrimitiveAssembler {
     void SubmitVertex(const VertexType& vtx, TriangleHandler triangle_handler);
 
     /**
+     * Invert the vertex order of the next triangle. Called by geometry shader emitter.
+     * This only takes effect for TriangleTopology::Shader.
+     */
+    void SetWinding();
+
+    /**
      * Resets the internal state of the PrimitiveAssembler.
      */
     void Reset();
@@ -45,6 +51,7 @@ private:
     int buffer_index;
     VertexType buffer[2];
     bool strip_ready = false;
+    bool winding = false;
 };
 
 } // namespace