fix inf_cone plane intersection tests

typed-geometry @ 8b84eb75

-Subproject commit e1b6ba80c076f446f7943b83ae3992ce7751fb24
+Subproject commit 8b84eb7530b201630c291c88f279ff9b3321d8d9

tests/feature/intersections/plane-intersect.cc

@@ -148,22 +148,53 @@ TG_FUZZ_TEST(Plane, Intersect)
         auto const center = uniform(rng, box);
         auto const d = tg::uniform<tg::dir3>(rng);
 
-        auto const c = tg::inf_cone<3, tg::f32>(center, d, tg::degree(uniform(rng, 1.0f, 80.0f)));
+        auto opening_angle = tg::degree(uniform(rng, 1.0f, 89.0f));
+        auto c = tg::inf_cone<3, tg::f32>(center, d, opening_angle);
 
+        // checking whether flipping the plane's normal makes a difference (should not)
+        {
             auto p = tg::plane3(d, center + d);
             CHECK(intersects(c, p));
+            auto c = tg::inf_cone<3, tg::f32>(center, -d, opening_angle);
+            CHECK(!intersects(c, p));
+        }
 
-        p = tg::plane3(d, center - d);
+        {
+            auto p = tg::plane3(-d, center + d);
+            CHECK(intersects(c, p));
+            auto c = tg::inf_cone<3, tg::f32>(center, -d, opening_angle);
             CHECK(!intersects(c, p));
+        }
+
+        {
+            auto p = tg::plane3(d, center - d);
+            CHECK(!intersects(c, p));
+            auto c = tg::inf_cone<3, tg::f32>(center, -d, opening_angle);
+            CHECK(intersects(c, p));
+        }
 
-        p.normal = any_normal(d);
+        {
+            auto p = tg::plane3(-d, center - d);
+            CHECK(!intersects(c, p));
+            auto c = tg::inf_cone<3, tg::f32>(center, -d, opening_angle);
+            CHECK(intersects(c, p));
+        }
 
-        auto rotation_mat = tg::rotation_around(any_normal(d), c.opening_angle);
-        auto new_normal = normalize(rotation_mat * d);
-        new_normal = any_normal(new_normal);
-        p = tg::plane3(new_normal, center + d * 100);
+        // rotate plane normal so that it intersects/does not intersect the cone
+        {
+            auto rotation_mat = tg::rotation_around(any_normal(d), tg::degree(89) - c.opening_angle);
+            auto new_normal = normalize(rotation_mat * (-d));
+            auto p = tg::plane3(new_normal, center - d);
 
-        // TODO should not intersect! is moved away from center and normal is oriented so that the plane runs parallel to the cone (?)
             CHECK(!intersects(c, p));
         }
+
+        {
+            auto rotation_mat = tg::rotation_around(any_normal(d), tg::degree(91) - c.opening_angle);
+            auto new_normal = normalize(rotation_mat * (-d));
+            auto p = tg::plane3(new_normal, center - d);
+
+            CHECK(intersects(c, p));
+        }
+    }
 }