Function GetNearestLedgeAngle

TombEngine/Game/collision/collide_room.cpp:752–1057

Determines vertical surfaces and gets nearest ledge angle. Allows to eventually use unconstrained vaults and shimmying.

// Determines vertical surfaces and gets nearest ledge angle.
// Allows to eventually use unconstrained vaults and shimmying.
short GetNearestLedgeAngle(ItemInfo* item, CollisionInfo* coll, float& distance)
{
	// Calculation ledge angle for non-Lara objects is unnecessary.
	if (!item->IsLara())
		return 0; 

	// Get item bounds and current rotation.
	auto bounds = GameBoundingBox(item);
	float cosForwardAngle = phd_cos(coll->Setup.ForwardAngle);
	float sinForwardAngle = phd_sin(coll->Setup.ForwardAngle);

	// Origin test position should be slightly in front of origin, because otherwise misfire may occur near block corners for split angles.
	auto frontalOffset = coll->Setup.Radius * 0.3f;
	auto x = item->Pose.Position.x + frontalOffset * sinForwardAngle;
	auto z = item->Pose.Position.z + frontalOffset * cosForwardAngle;

	// Determine two Y points to test (lower and higher).
	// 1/10 headroom crop is needed to avoid possible issues with tight diagonal headrooms.
	int headroom = bounds.GetHeight() / 20.0f;
	int yPoints[2] = { item->Pose.Position.y + bounds.Y1 + headroom,
					   item->Pose.Position.y + bounds.Y2 - headroom };

	// Prepare test data.
	float finalDistance[2] = { FLT_MAX, FLT_MAX };
	short finalResult[2] = { 0 };
	bool  hitBridge = false;

	// Do a two-pass surface test for all possible planes in a block.
	// Two-pass test is needed to resolve different scissor cases with diagonal geometry.
	for (int h = 0; h < 2; h++)
	{
		// Use either bottom or top Y point to test.
		auto y = yPoints[h];

		// Prepare test data.
		Ray   originRay;
		Plane closestPlane[3] = { };
		float closestDistance[3] = { FLT_MAX, FLT_MAX, FLT_MAX };
		short result[3] = { };

		// If bridge was hit on the first pass, stop checking.
		if (h == 1 && hitBridge)
			break;

		for (int p = 0; p < 3; p++)
		{
			// Prepare test data.
			float dist = 0.0f;

			// Determine horizontal probe coordinates.
			auto eX = x;
			auto eZ = z;

			// Determine if probe must be shifted (if left or right probe).
			if (p > 0)
			{
				auto s2 = phd_sin(coll->Setup.ForwardAngle + (p == 1 ? ANGLE(90.0f) : -ANGLE(90.0f)));
				auto c2 = phd_cos(coll->Setup.ForwardAngle + (p == 1 ? ANGLE(90.0f) : -ANGLE(90.0f)));