test: add tests for camera view-frustum culling planes

tests/testFrustum.cpp

@@ -0,0 +1,47 @@
+#include "testHarness.h"
+#include "vf/Frustum.h"
+
+using namespace vf;
+
+namespace {
+
+Frustum makeFrustum() {
+    Mat4 proj = perspective(1.0472f, 1.3333f, 0.1f, 100.0f);   // 60 degrees
+    Mat4 view = lookAt({0, 0, 5}, {0, 0, 0}, {0, 1, 0});       // camera looks toward -z
+    return Frustum::fromMatrix(proj * view);
+}
+
+} // namespace
+
+VF_TEST(frustumPointInFrontIsVisible) {
+    Frustum f = makeFrustum();
+    CHECK(f.containsPoint({0, 0, 0}));
+    CHECK(f.containsPoint({0, 0, -10}));
+}
+
+VF_TEST(frustumPointBehindCameraIsCulled) {
+    Frustum f = makeFrustum();
+    CHECK(!f.containsPoint({0, 0, 10}));
+}
+
+VF_TEST(frustumPointBeyondFarIsCulled) {
+    Frustum f = makeFrustum();
+    CHECK(!f.containsPoint({0, 0, -200}));
+}
+
+VF_TEST(frustumWideOffAxisPointIsCulled) {
+    Frustum f = makeFrustum();
+    CHECK(!f.containsPoint({100, 0, -1}));
+}
+
+VF_TEST(frustumAabbInViewIntersects) {
+    Frustum f = makeFrustum();
+    Aabb box{{-1, -1, -2}, {1, 1, 0}};
+    CHECK(f.intersectsAabb(box));
+}
+
+VF_TEST(frustumAabbBehindCameraCulled) {
+    Frustum f = makeFrustum();
+    Aabb box{{-1, -1, 20}, {1, 1, 22}};
+    CHECK(!f.intersectsAabb(box));
+}