polylib: make winding printable for debugging/testing

include/common/polylib.hh

@@ -16,6 +16,8 @@
 #include <stdexcept>
 #include <optional>
 
+#include <fmt/ostream.h>
+
 #include <tbb/scalable_allocator.h>
 
 namespace polylib
@@ -1278,8 +1280,25 @@ public:
 
         return result;
     }
+
+    // gtest support
+    // also, makes printable via fmt since we include fmt/ostream.h
+    friend std::ostream& operator<<(std::ostream& os, const winding_base_t &winding) {
+        os << "{";
+        for (size_t i = 0; i < winding.size(); ++i) {
+            os << "(" << winding[i] << ")";
+            if ((i + 1) < winding.size())
+                os << ", ";
+        }
+        os << "}";
+        return os;
+    }
 };
 
+// fmt support
+template<class T>
+struct fmt::formatter<winding_base_t<T>> : fmt::ostream_formatter {};
+
 // the default amount of points to keep on stack
 constexpr size_t STACK_POINTS_ON_WINDING = MAX_POINTS_ON_WINDING / 4;
 

tests/test_light.cc

@@ -980,6 +980,16 @@ TEST(mathlib, clampTexcoord)
     EXPECT_EQ(127, clamp_texcoord(-129.0f, 128));
 }
 
+TEST(mathlib, windingFormat)
+{
+    const polylib::winding_t poly{{0, 0, 0}, {0, 64, 0}, {64, 64, 0}, {64, 0, 0}};
+
+    const char *exp = "{(0 0 0), (0 64 0), (64 64 0), (64 0 0)}";
+
+    EXPECT_EQ(exp, testing::PrintToString(poly));
+    EXPECT_EQ(exp, fmt::format("{}", poly));
+}
+
 TEST(Settings, delayDefault)
 {
     light_t light;