[GPU] Fix quads>triangles cvar, primitive type test cases

src/xenia/gpu/primitive_processor.cc

@@ -331,7 +331,7 @@ bool PrimitiveProcessor::Process(ProcessingResult& result_out) {
         break;
       case xenos::PrimitiveType::kQuadList:
         if (convert_quad_lists_to_triangle_lists_) {
-          host_primitive_type = xenos::PrimitiveType::kQuadList;
+          host_primitive_type = xenos::PrimitiveType::kTriangleList;
         }
         break;
       default:

src/xenia/gpu/primitive_processor.h

@@ -509,6 +509,14 @@ class PrimitiveProcessor {
     }
   };
 
+  // Triangle fan test cases:
+  // - 4D5307E6 - main menu - game logo, developer logo, backgrounds of the menu
+  //   item list (the whole menu and individual items) - no index buffer.
+  // - 4E4D87E6 - terrain - with an index buffer and primitive reset (note that
+  //   there, vfetch indices are computed in the vertex shader, involving
+  //   floating-point reciprocal, so this case is very sensitive to rounding,
+  //   and incorrect geometry may occur not because of vertex grouping issues,
+  //   but also due to the behavior of the vertex shader).
   // Triangle fans as triangle lists.
   // Ordered as (v1, v2, v0), (v2, v3, v0) in Direct3D.
   // https://docs.microsoft.com/en-us/windows/desktop/direct3d9/triangle-fans
@@ -565,6 +573,8 @@ class PrimitiveProcessor {
                               uint32_t source_index_count,
                               const PassthroughIndexTransform& index_transform);
 
+  // Quad list test cases:
+  // - 4D5307E6 - main menu - flying dust on the road - no index buffer.
   static constexpr uint32_t GetQuadListTriangleListIndexCount(
       uint32_t quad_list_index_count) {
     return (quad_list_index_count / 4) * 6;