Function AlignEntityToSurface

TombEngine/Game/collision/collide_room.cpp:702–737

}

void AlignEntityToSurface(ItemInfo* item, const Vector2& ellipse, float alpha, short constraintAngle)
{
	// Reduce ellipse axis lengths for stability.
	auto reducedEllipse = ellipse * 0.75f;

	// Probe heights at points around entity.
	int frontHeight = GetPointCollision(*item, item->Pose.Orientation.y, reducedEllipse.y).GetFloorHeight();
	int backHeight	= GetPointCollision(*item, item->Pose.Orientation.y + ANGLE(180.0f), reducedEllipse.y).GetFloorHeight();
	int leftHeight	= GetPointCollision(*item, item->Pose.Orientation.y - ANGLE(90.0f), reducedEllipse.x).GetFloorHeight();
	int rightHeight = GetPointCollision(*item, item->Pose.Orientation.y + ANGLE(90.0f), reducedEllipse.x).GetFloorHeight();

	// Calculate height deltas.
	int forwardHeightDelta = backHeight - frontHeight;
	int lateralHeightDelta = rightHeight - leftHeight;

	// Calculate extra rotation required.
	auto extraRot = EulerAngles(
		FROM_RAD(atan2(forwardHeightDelta, ellipse.y * 2)),
		0,
		FROM_RAD(atan2(lateralHeightDelta, ellipse.x * 2))) -
		EulerAngles(item->Pose.Orientation.x, 0, item->Pose.Orientation.z);

	// Rotate X axis.
	if (abs(forwardHeightDelta) <= STEPUP_HEIGHT)
	{
		if (abs(extraRot.x) <= constraintAngle)
			item->Pose.Orientation.x += extraRot.x * alpha;
	}

	// Rotate Z axis.
	if (abs(lateralHeightDelta) <= STEPUP_HEIGHT)
	{
		if (abs(extraRot.z) <= constraintAngle)
			item->Pose.Orientation.z += extraRot.z * alpha;
	}
}

int GetQuadrant(short angle)
{