十字路口 (Intersections)

To find the intersection of nodes with bounds of the specified volume, you should use functions that have a bounding volume and a vector of nodes in arguments:为了找到节点与指定体积的边界的交集，你应该使用具有边界体积和节点向量的函数参数:

• int getIntersection(const Math::WorldBoundBox & bb, Vector< Ptr<Node> > & nodes)
• int getIntersection(const Math::WorldBoundSphere & bs, Vector< Ptr<Node> > & nodes)
• int getIntersection(const Math::WorldBoundBox & bb, int type, Vector< Ptr<Node> > & nodes)
• int getIntersection(const Math::WorldBoundSphere & bs, int type, Vector< Ptr<Node> > & nodes)
• int getIntersection(const Math::WorldBoundFrustum & bf, int type, Vector< Ptr<Node> > & nodes)

Schematic visual representation of intersection with nodes in bounding volume与包围体中的节点相交的示意图视觉表示

These functions return the value indicating the result of the intersection search: 1 if the intersection was found; otherwise, 0. Intersected nodes can be found in the vector that passed as an argument to the function.这些函数返回值指示交叉搜索的结果:1 如果十字路口被发现;否则, 0 。交叉节点可以在向量作为参数传递给函数。

To clarify the nodes search, specify the type of node to search.要明确节点搜索，请指定要搜索的节点类型。

The following functions can be used to perform the intersection search with objects:可以使用以下函数对对象进行交集搜索:

• int getIntersection(const Math::Vec3 & p0, const Math::Vec3 & p1, Vector< Ptr<Object> > & objects, bool check_surface_flags)
• int getIntersection(const Math::WorldBoundBox & bb, Vector< Ptr<Object> > & objects)
• int getIntersection(const Math::WorldBoundSphere & bs, Vector< Ptr<Object> > & objects)
• int getIntersection(const Math::WorldBoundFrustum & bf, Vector< Ptr<Object> > & objects)
• bool getVisibleIntersection(const Math::Vec3& camera, const Math::WorldBoundFrustum& bf, Vector< Ptr<Object> > & objects, float max_distance)
• bool getVisibleIntersection(const Math::Vec3& camera, const Math::WorldBoundFrustum& bf, Node::TYPE type, Vector< Ptr<Node> > & nodes, float max_distance)

Schematic visual representation of intersection with objects in bounding volume原理图可视化表示边界交点与对象的体积

These functions return the value indicating the result of the intersection search: 1 if the intersection was found; otherwise, 0. You can pass the start (vec3 p0) and the end (vec3 p1) point of the intersecting line or pass the (BoundBox, BoundFrustum, BoundSphere) to get the intersection of objects with a line or with a bounding volume, respectively. Intersected nodes can be found in the vector that passed as an argument to the function.这些函数返回指示交集搜索结果的值:如果找到交集，则返回1;否则,0。您可以通过相交线的起始点(vec3 p0)和结束点(vec3 p1)或通过(BoundBox, BoundFrustum, BoundSphere)分别获得对象与直线或边界体的交点。交叉节点可以在作为参数传递给函数的向量中找到。

For WorldBoundFrustum, there are two modes of getting intersections:对于WorldBoundFrustum，有两种获取交叉口的模式:

• Intersections with the objects that are visible inside the frustum — getVisibleIntersection()十字路口的对象 可见平截头体- getVisibleIntersection()内部
• Intersections with all objects inside the frustum, both visible and invisible — getIntersection()与截锥内的所有对象相交，可见和不可见 - getIntersection()

The following functions are used to find the nearest intersected object with the traced line. You should specify the start point and the end point of the line, and the function detects if there are any object on the way of this line.以下功能是用来找到最近的追踪线分割的对象。你应该指定起点和终点的线,和功能检测是否有对象在这条线的方法。

• Ptr<Object> getIntersection(const Math::Vec3 & p0, const Math::Vec3 & p1, int mask, Math::Vec3 * ret_point, Math::vec3 * ret_normal, Math::vec4 * ret_texcoord, int * ret_index, int * ret_surface)
• Ptr<Object> getIntersection(const Math::Vec3 & p0, const Math::Vec3 & p1, int mask, const Vector< Ptr<Node> > & exclude, Math::Vec3 * ret_point, Math::vec3 * ret_normal, Math::vec4 * ret_texcoord, int * ret_index, int * ret_surface)
• Ptr<Object> getIntersection(const Math::Vec3 & p0, const Math::Vec3 & p1, int mask, const Ptr<WorldIntersection> & v)
• Ptr<Object> getIntersection(const Math::Vec3 & p0, const Math::Vec3 & p1, int mask, const Ptr<WorldIntersectionNormal> & v)
• Ptr<Object> getIntersection(const Math::Vec3 & p0, const Math::Vec3 & p1, int mask, const Ptr<WorldIntersectionTexCoord> & v)
• Ptr<Object> getIntersection(const Math::Vec3 & p0, const Math::Vec3 & p1, int mask, const Vector< Ptr<Node> > & exclude, const Ptr<WorldIntersection> & v)
• Ptr<Object> getIntersection(const Math::Vec3 & p0, const Math::Vec3 & p1, int mask, const Vector< Ptr<Node> > & exclude, const Ptr<WorldIntersectionNormal> & v)
• Ptr<Object> getIntersection(const Math::Vec3 & p0, const Math::Vec3 & p1, int mask, const Vector< Ptr<Node> > & exclude, const Ptr<WorldIntersectionTexCoord> & v)

Schematic visual representation of intersection with objects and traced line与物体和跟踪线相交的示意图可视化表示

These functions return an intersection information and a pointer to the nearest object to the start point (p0). Information about the intersection can be presented in standard vectors or in the following format that you pass to functions as arguments:这些函数返回一个路口信息和最近的对象指针(p0)的起始点。十字路口的信息可以在以下格式,提出了标准向量或作为参数传递给函数:

• WorldIntersection intersection — the WorldIntersection class instance. By using this class you can get the intersection point (coordinates), the index of the intersected triangle of the object and the index of the intersected surface.WorldIntersection intersection—WorldIntersection类实例。通过使用这个类，您可以得到交点(坐标)、对象的相交三角形的索引和相交曲面的索引。
• WorldIntersectionNormal normal — the WorldIntersectionNormal class instance. By using this class you can get only the normal of the intersection point.WorldIntersectionNormal normal - WorldIntersectionNormal类实例。通过使用这个类可以得到只有正常的交点。
• WorldIntersectionTexCoord texcoord — the WorldIntersectionTexCoord class instance. By using this class you can get only the texture coordinates of the intersection point.WorldIntersectionTexCoord texcoord—WorldIntersectionTexCoord类实例。通过使用这个类，你只能得到交点的纹理坐标。

These functions detect intersection with surfaces (polygons) of meshes. But there are some conditions to detect the intersection with the surface:这些函数检测与网格表面(多边形)的交集。但检测与曲面的交集有以下几个条件:

1. The surface is enabled.表面已启用。
2. The surface has a material assigned.表面材质分配。

3. Per-surface Intersection flag is enabled.启用每个表面的Intersection标志。

   注意

   You can set this flag to the object's surface by using the Object.setIntersection() function.你可以设置这个标志对象的表面使用Object.setIntersection()函数。

To clarify the object search, perform the following:要澄清对象搜索，请执行以下操作:

• Use an Intersection mask. An intersection is found only if an object is matching the Intersection mask.使用Intersection掩码。只有当对象匹配Intersection掩码时才会找到交集。
• Specify the list of objects (nodes) to exclude and pass to the function as an argument.指定的对象列表(节点)排除并传递函数作为参数。

The following example shows how you can get the intersection information by using the PhysicsIntersection class. In this example we specify a line from the point of the camera (vec3 p0) to the point of the mouse pointer (vec3 p1). The executing sequence is the following:下面的例子显示了如何获得交叉的信息通过使用PhysicsIntersection类。在这个示例中,我们指定一个线从相机(vec3 p0)的鼠标指针(vec3 p1)。执行顺序如下:

1. Define and initialize two points (p0 and p1) by using the Player::getDirectionFromScreen() function.使用Player::getDirectionFromScreen()函数定义并初始化两个点(p0和p1)。
2. Create an instance of the PhysicsIntersection class to get the intersection information.创建一个PhysicsIntersection类的实例来获得交叉的信息。
3. Check if there is an intersection with an object with a shape or a collision object. The getIntersection() function returns an intersected object when the object intersects with the traced line.检查是否有一个相交的对象与形状或碰撞对象。当对象与跟踪的直线相交时，getIntersection()函数返回一个相交的对象。
4. When the object intersects with the traced line, all surfaces of the intersected object change their material parameters. If the object has a shape, its information will be shown in console. The PhysicsIntersection class instance gets the coordinates of the intersection point and the Shape class object. You can get all these fields by using getShape(), getPoint() functions.当追踪的对象相交线,所有的表面分割对象的改变他们的材质参数。如果对象有一个形状,其信息将显示在控制台。PhysicsIntersection类实例得到交点的坐标和Shape类对象。你可以得到所有这些字段使用getShape(), getPoint()功能。

#include "AppWorldLogic.h"
#include <UnigineObjects.h>
#include <UnigineEditor.h>
#include <UnigineGame.h>
#include <UniginePhysics.h>

using namespace Unigine;
using namespace Math;

int AppWorldLogic::init()
{
	// create a Mesh instance with a box surface
	MeshPtr mesh = Mesh::create();
	mesh->addBoxSurface("box", vec3(0.2f));

	// create a new dynamic mesh from the Mesh instance
	ObjectMeshDynamicPtr dynamic_mesh = ObjectMeshDynamic::create(mesh);

	dynamic_mesh->setWorldTransform(translate(Vec3(0.0f, 0.0f, 2.0f)));

	// assign a body and a shape to the dynamic mesh
	BodyRigidPtr body = BodyRigid::create(dynamic_mesh);
	ShapeBoxPtr shape = ShapeBox::create(body, vec3(0.2f)); 

	return 1;
}

////////////////////////////////////////////////////////////////////////////////
// start of the main loop
////////////////////////////////////////////////////////////////////////////////

int AppWorldLogic::update()
{
	// initialize points of the mouse direction
	Vec3 p0, p1;

	// get the current player (camera)
	PlayerPtr player = Game::getPlayer();
	if (player.get() == NULL)
		return 0;
	// get width and height of the main application window
	Math::ivec2 winsize = WindowManager::getMainWindow()->getClientSize();
	int width = winsize.x;
	int height = winsize.y;
	// get the current X and Y coordinates of the mouse pointer
	int mouse_x = Gui::getCurrent()->getMouseX();
	int mouse_y = Gui::getCurrent()->getMouseY();
	// get the mouse direction from the player's position (p0) to the mouse cursor pointer (p1)
	player->getDirectionFromScreen(p0, p1, mouse_x, mouse_y, 0, 0, width, height);

	// create the instance of the PhysicsIntersection object to save the information about the intersection
	PhysicsIntersectionPtr intersection = PhysicsIntersection::create();
	// get an intersection
	ObjectPtr object = Physics::getIntersection(p0, p1, 1, intersection);

	// if the intersection has occurred, change the parameter of the object's material    
	if (object)
	{
		for (int i = 0; i < object->getNumSurfaces(); i++)
		{
			object->setMaterialParameterFloat4("albedo_color", vec4(1.0f, 1.0f, 0.0f, 1.0f), i);
		}

		// if the intersected object has a shape, show the information about the intersection   
		ShapePtr shape = intersection->getShape();
		if (shape)
		{
			Log::message("physics intersection info: point: (%f %f %f) shape: %s\n", intersection->getPoint().x, intersection->getPoint().y, intersection->getPoint().z, shape->getTypeName());
		}
	}

	return 1;
}

The following example shows how you can get the intersection point (vec3) of the cylinder between two points with an obstacle. We'll do the following:下面的例子展示了如何获得圆柱体与障碍物之间的交点(vec3)。我们将执行以下操作:

1. Create an instance of the ObstacleBox class on the application initialization.创建一个ObstacleBox类的实例应用程序初始化。
2. Define two points (p1 and p2) that specify the beginning and the end of the cylinder.Define两个点(p1和p2) ，指定柱面的开始和结束。
3. Create an instance of the GameIntersection class to get the intersection point coordinates.创建一个GameIntersection类的实例的交点坐标。
4. Check if there is an intersection with an obstacle. The Game::getIntersection() function returns an intersected obstacle when the obstacle appears in the area of the cylinder.检查交叉路口是否有障碍物。当障碍物出现在圆柱区域时，Game::getIntersection()函数返回一个相交的障碍物。
5. When the GameIntersection instance intersects with an obstacle, you can get its name using the getName() function or any other details using the corresponding functions.当GameIntersection实例与障碍物相交时，您可以使用getName()函数获得它的名称，或者使用相应的函数获得任何其他细节。

#include "AppWorldLogic.h"
#include <UnigineObjects.h>
#include <UnigineEditor.h>

#include <UniginePathFinding.h>
#include <UnigineGame.h>

using namespace Unigine;
using namespace Math;

int AppWorldLogic::init()
{
	Visualizer::setEnabled(true);

		// create an obstacle
	obstacle_box = ObstacleBox::create(vec3(1.0f));
	obstacle_box->setName("main_obstacle");
	
	return 1;
}

int AppWorldLogic::update()
{

	// make the obstacle box move inside and outside the game intersection area
	Vec3 new_pos = Vec3(0, 0, 2 + Math::sin(Game::getTime()));
	obstacle_box->setWorldPosition(new_pos);
	Visualizer::renderPoint3D(new_pos, 0.15f, vec4(1, 0, 1, 1));

	// calculate the cylinder height (equals to the distance between the start and end points)
	Visualizer::renderPoint3D(p1, 0.15f, vec4(0, 0, 1, 1));
	Visualizer::renderPoint3D(p2, 0.15f, vec4(0, 1, 1, 1));

	// create an instance of the GameIntersection class
	GameIntersectionPtr intersection = GameIntersection::create();
	ObstaclePtr obstacle = Game::getIntersection(p1, p2, radius, 1, intersection);

	//visualize the cylinder that represents the game intersection area
	Visualizer::renderCylinder(radius, (p2 - p1).length(), setTo(p1 + (p2 - p1) / 2, p2, vec3_up, AXIS_Z), vec4(1, 1, 1, 1));

	// check if the intersection of the cylinder with the obstacle has occurred
	if (obstacle)
	{
		obstacle->renderVisualizer();
		Log::message("The name of the obstacle is: (%s)\n", obstacle->getName());

	}
	return 1;

}