Add basic unit tests for collisionMoveSimple

src/collision.cpp

@@ -21,6 +21,8 @@
 #warning "-ffast-math is known to cause bugs in collision code, do not use!"
 #endif
 
+bool g_collision_problems_encountered = false;
+
 namespace {
 
 struct NearbyCollisionInfo {
@@ -342,6 +344,7 @@ collisionMoveResult collisionMoveSimple(Environment *env, IGameDef *gamedef,
 			warningstream << "collisionMoveSimple: maximum step interval exceeded,"
 					" lost movement details!"<<std::endl;
 		}
+		g_collision_problems_encountered = true;
 		dtime = DTIME_LIMIT;
 	} else {
 		time_notification_done = false;
@@ -415,7 +418,8 @@ collisionMoveResult collisionMoveSimple(Environment *env, IGameDef *gamedef,
 		// Avoid infinite loop
 		loopcount++;
 		if (loopcount >= 100) {
-			warningstream << "collisionMoveSimple: Loop count exceeded, aborting to avoid infiniite loop" << std::endl;
+			warningstream << "collisionMoveSimple: Loop count exceeded, aborting to avoid infinite loop" << std::endl;
+			g_collision_problems_encountered = true;
 			break;
 		}
 

src/collision.h

@@ -37,6 +37,8 @@ struct CollisionInfo
 	v3f new_pos;
 	v3f old_speed;
 	v3f new_speed;
+
+	// FIXME: this is equivalent to `axis`, why does it exist?
 	int plane = -1;
 };
 
@@ -44,12 +46,16 @@ struct collisionMoveResult
 {
 	collisionMoveResult() = default;
 
-	bool touching_ground = false;
 	bool collides = false;
+	bool touching_ground = false;
 	bool standing_on_object = false;
 	std::vector<CollisionInfo> collisions;
 };
 
+/// Status if any problems were ever encountered during collision detection.
+/// @warning For unit test use only.
+extern bool g_collision_problems_encountered;
+
 /// @brief Moves using a single iteration; speed should not exceed pos_max_d/dtime
 /// @param self (optional) ActiveObject to ignore in the collision detection.
 collisionMoveResult collisionMoveSimple(Environment *env,IGameDef *gamedef,

src/dummymap.h

@@ -24,5 +24,19 @@ public:
 
 	~DummyMap() = default;
 
+	void fill(v3s16 bpmin, v3s16 bpmax, MapNode n)
+	{
+		for (s16 z = bpmin.Z; z <= bpmax.Z; z++)
+		for (s16 y = bpmin.Y; y <= bpmax.Y; y++)
+		for (s16 x = bpmin.X; x <= bpmax.X; x++) {
+			MapBlock *block = getBlockNoCreateNoEx({x, y, z});
+			if (block) {
+				for (size_t i = 0; i < MapBlock::nodecount; i++)
+					block->getData()[i] = n;
+				block->expireIsAirCache();
+			}
+		}
+	}
+
 	bool maySaveBlocks() override { return false; }
 };

src/unittest/test_collision.cpp

@@ -3,6 +3,9 @@
 // Copyright (C) 2013 celeron55, Perttu Ahola <celeron55@gmail.com>
 
 #include "test.h"
+#include "dummymap.h"
+#include "environment.h"
+#include "irrlicht_changes/printing.h"
 
 #include "collision.h"
 
@@ -14,6 +17,7 @@ public:
 	void runTests(IGameDef *gamedef);
 
 	void testAxisAlignedCollision();
+	void testCollisionMoveSimple(IGameDef *gamedef);
 };
 
 static TestCollision g_test_instance;
@@ -21,8 +25,42 @@ static TestCollision g_test_instance;
 void TestCollision::runTests(IGameDef *gamedef)
 {
 	TEST(testAxisAlignedCollision);
+	TEST(testCollisionMoveSimple, gamedef);
 }
 
+namespace {
+	class TestEnvironment : public Environment {
+		DummyMap map;
+	public:
+		TestEnvironment(IGameDef *gamedef)
+			: Environment(gamedef), map(gamedef, {-1, -1, -1}, {1, 1, 1})
+		{
+			map.fill({-1, -1, -1}, {1, 1, 1}, MapNode(CONTENT_AIR));
+		}
+
+		void step(f32 dtime) override {}
+
+		Map &getMap() override { return map; }
+
+		void getSelectedActiveObjects(const core::line3d<f32> &shootline_on_map,
+			std::vector<PointedThing> &objects,
+			const std::optional<Pointabilities> &pointabilities) override {}
+	};
+}
+
+#define UASSERTEQ_F(actual, expected) do { \
+		f32 a = (actual); \
+		f32 e = (expected); \
+		UTEST(fabsf(a - e) <= 0.0001f, "actual: %.f expected: %.f", a, e) \
+	} while (0)
+
+#define UASSERTEQ_V3F(actual, expected) do { \
+		v3f va = (actual); \
+		v3f ve = (expected); \
+		UASSERTEQ_F(va.X, ve.X); UASSERTEQ_F(va.Y, ve.Y); UASSERTEQ_F(va.Z, ve.Z); \
+	} while (0)
+
+
 ////////////////////////////////////////////////////////////////////////////////
 
 void TestCollision::testAxisAlignedCollision()
@@ -163,3 +201,78 @@ void TestCollision::testAxisAlignedCollision()
 		}
 	}
 }
+
+#define fpos(x,y,z) (BS * v3f(x, y, z))
+
+void TestCollision::testCollisionMoveSimple(IGameDef *gamedef)
+{
+	auto env = std::make_unique<TestEnvironment>(gamedef);
+	g_collision_problems_encountered = false;
+
+	for (s16 x = 0; x < MAP_BLOCKSIZE; x++)
+	for (s16 z = 0; z < MAP_BLOCKSIZE; z++)
+		env->getMap().setNode({x, 0, z}, MapNode(t_CONTENT_STONE));
+
+	const f32 pos_max_d = 0.25f * BS; // ?
+	v3f pos, speed, accel;
+	const aabb3f box(fpos(-0.1f, 0, -0.1f), fpos(0.1f, 1.4f, 0.1f));
+	collisionMoveResult res;
+
+	/* simple movement with accel */
+	pos   = fpos(4, 1, 4);
+	speed = fpos(0, 0, 0);
+	accel = fpos(0, 1, 0);
+	res = collisionMoveSimple(env.get(), gamedef, pos_max_d, box, 0.0f, 1.0f,
+		&pos, &speed, accel);
+
+	UASSERT(!res.touching_ground || !res.collides || !res.standing_on_object);
+	UASSERT(res.collisions.empty());
+	// FIXME: it's easy to tell that this should be y=1.5f, but our code does it wrong.
+	// It's unclear if/how this will be fixed.
+	UASSERTEQ_V3F(pos, fpos(4, 2, 4));
+	UASSERTEQ_V3F(speed, fpos(0, 1, 0));
+
+	/* standing on ground */
+	pos   = fpos(0, 0.5f, 0);
+	speed = fpos(0, 0, 0);
+	accel = fpos(0, -9.81f, 0);
+	res = collisionMoveSimple(env.get(), gamedef, pos_max_d, box, 0.0f, 0.04f,
+		&pos, &speed, accel);
+
+	UASSERT(res.collides);
+	UASSERT(res.touching_ground);
+	UASSERT(!res.standing_on_object);
+	UASSERTEQ_V3F(pos, fpos(0, 0.5f, 0));
+	UASSERTEQ_V3F(speed, fpos(0, 0, 0));
+	UASSERT(res.collisions.size() == 1);
+	{
+		auto &ci = res.collisions.front();
+		UASSERTEQ(int, ci.type, COLLISION_NODE);
+		UASSERTEQ(int, ci.axis, COLLISION_AXIS_Y);
+		UASSERTEQ(v3s16, ci.node_p, v3s16(0, 0, 0));
+	}
+
+	/* not moving never collides */
+	pos   = fpos(0, -100, 0);
+	speed = fpos(0, 0, 0);
+	accel = fpos(0, 0, 0);
+	res = collisionMoveSimple(env.get(), gamedef, pos_max_d, box, 0.0f, 1/60.0f,
+		&pos, &speed, accel);
+	UASSERT(!res.collides);
+
+	/* collision in ignore */
+	pos   = fpos(0, -100, 0);
+	speed = fpos(5, 0, 0);
+	accel = fpos(0, 0, 0);
+	res = collisionMoveSimple(env.get(), gamedef, pos_max_d, box, 0.0f, 1/60.0f,
+		&pos, &speed, accel);
+	UASSERTEQ_V3F(speed, fpos(0, 0, 0));
+	UASSERT(!res.collides); // FIXME this is actually inconsistent
+	UASSERT(res.collisions.empty());
+
+	// TODO things to test:
+	// standing_on_object, multiple collisions, bouncy, stepheight
+
+	// No warnings should have been raised during our test.
+	UASSERT(!g_collision_problems_encountered);
+}