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:

• bool GetIntersection(WorldBoundBox bb, ICollection<Node> nodes)
• bool GetIntersection(WorldBoundSphere bs, ICollection<Node> nodes)
• bool GetIntersection(WorldBoundBox bb, int type, ICollection<Node> nodes)
• bool GetIntersection(WorldBoundSphere bs, int type, ICollection<Node> nodes)
• bool GetIntersection(WorldBoundFrustum bf, int type, ICollection<Node> nodes)

Schematic visual representation of intersection with nodes in bounding volume原理图可视化表示的十字路口节点边界体积

These functions return the value indicating the result of the intersection search: true if the intersection was found; otherwise, false. Intersected nodes can be found in the collection that passed as an argument to the function.这些函数返回指示交集搜索结果的值: true如果找到交集;否则,假。交叉的节点可以在作为参数传递给函数的集合中找到。

To clarify the nodes search, specify the type of node to search.澄清节点搜索,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:

• bool GetIntersection(Vec3 p0, Vec3 p1, ICollection<Object> objects, bool check_surface_flags)
• bool GetIntersection(WorldBoundBox bb, ICollection<Object> objects)
• bool GetIntersection(WorldBoundSphere bs, ICollection<Object> objects)
• bool GetIntersection(WorldBoundFrustum bf, ICollection<Object> objects)
• bool GetVisibleIntersection (vec3 camera, WorldBoundFrustum bf, Object[] objects, float max_distance)
• int GetVisibleIntersection( vec3 camera, WorldBoundFrustum bf, Node.TYPE type, 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: true if the intersection was found; otherwise, false. 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 collection 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true;否则,false。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。交叉的节点可以在作为参数传递给函数的集合中找到。

For WorldBoundFrustum, there are two modes of getting intersections:For WorldBoundFrustum, there are two modes of getting intersections:

• Intersections with the objects that are visible inside the frustum — GetVisibleIntersection()与截锥内 visible的对象相交- GetVisibleIntersection()
• Intersections with all objects inside the frustum, both visible and invisible — GetIntersection()路口截锥体内的所有对象,有形 和无形的 - 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.下面的函数用于找到与跟踪线最近的相交对象。您应该指定行的起始点和结束点，该函数会检测这条线的路径上是否有任何对象。

• Object GetIntersection(Vec3 p0, Vec3 p1, int mask, Vec3[] ret_point, vec3[] ret_normal, vec4[] ret_texcoord, int[] ret_index, int[] ret_surface)
• Object GetIntersection(Vec3 p0, Vec3 p1, int mask, Node[] exclude, Vec3[] ret_point, vec3[] ret_normal, vec4[] ret_texcoord, int[] ret_index, int[] ret_surface)
• Object GetIntersection(Vec3 p0, Vec3 p1, int mask, WorldIntersection v)
• Object GetIntersection(Vec3 p0, Vec3 p1, int mask, WorldIntersectionNormal v)
• Object GetIntersection(Vec3 p0, Vec3 p1, int mask, WorldIntersectionTexCoord v)
• Object GetIntersection(Vec3 p0, Vec3 p1, int mask, Node[] exclude, WorldIntersection v)
• Object GetIntersection(Vec3 p0, Vec3 p1, int mask, Node[] exclude, WorldIntersectionNormal v)
• Object GetIntersection(Vec3 p0, Vec3 p1, int mask, Node[] exclude, 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，你只能得到交点的法线。
• 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。通过使用这个类可以得到唯一的交点的纹理坐标。

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.表面是启用的。
2. The surface has a material assigned.该表面已指定了一种材质。

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.使用一个Intersection面具。一个十字路口被发现只有一个对象匹配Intersection面具。
• Specify the list of objects (nodes) to exclude and pass to the function as an argument.指定要排除的对象(节点)列表，并将其作为参数传递给函数。

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:下面的示例展示了如何通过使用PhysicsIntersection类获取交集信息。在这个例子中，我们指定了一条从相机(vec3 p0)点到鼠标指针(vec3 p1)点的直线。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 Shape, Point properties.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Shape, Point属性。

using System;
using System.Collections;
using System.Collections.Generic;
using Unigine;

#if UNIGINE_DOUBLE
    using Vec3 = Unigine.dvec3;
    using Vec4 = Unigine.dvec4;
    using Mat4 = Unigine.dmat4;
#else
    using Vec3 = Unigine.vec3;
    using Vec4 = Unigine.vec4;
    using Mat4 = Unigine.mat4;
#endif

[Component(PropertyGuid = "AUTOGENERATED_GUID")] // <-- this line is generated automatically for a new component
public class PhysicsIntersectionClass : Component
{
	private void Init()
	{
		// create a mesh instance with a box surface
		Mesh mesh = new Mesh();
		mesh.AddBoxSurface("box", new vec3(2.2f));
		
		// create a new dynamic mesh from the Mesh instance
		ObjectMeshDynamic dynamic_mesh = new ObjectMeshDynamic(mesh);

		dynamic_mesh.WorldTransform = MathLib.Translate(new Vec3(0.0f, 0.0f, 2.0f));

		// assign a body and a shape to the dynamic mesh
		BodyRigid body = new BodyRigid(dynamic_mesh);
		ShapeBox shape = new ShapeBox(body, new vec3(2.2f));
	}
	private void Update()
	{
		// initialize points of the mouse direction
		Vec3 p0, p1;

		// get the current player (camera)
		Player player = Game.Player;
			
		// get the size of the current application window
		EngineWindow main_window = WindowManager.MainWindow;
		if (!main_window)
		{
			Engine.Quit();
			return;
		}

		ivec2 main_size = main_window.Size;

		// get the current X and Y coordinates of the mouse pointer
		int mouse_x = Gui.GetCurrent().MouseX;
		int mouse_y = Gui.GetCurrent().MouseY;
		// get the mouse direction from the player's position (p0) to the mouse cursor pointer (p1)
		player.GetDirectionFromScreen(out p0, out p1, mouse_x, mouse_y, 0, 0, main_size.x, main_size.y);

		// create the instance of the PhysicsIntersection object to save the information about the intersection
		PhysicsIntersection intersection = new PhysicsIntersection();
		// get an intersection
		Unigine.Object obj = Physics.GetIntersection(p0, p1, 1, intersection);

		// if the intersection has occurred, change the parameter of the object's material    
		if (obj != null)
		{
			for (int i = 0; i < obj.NumSurfaces; i++)
			{
				obj.SetMaterialParameterFloat4("albedo_color", new vec4(1.0f, 1.0f, 0.0f, 1.0f), i);
			}

			// if the intersected object has a shape, show the information about the intersection   
			Shape shape = intersection.Shape;
			if (shape != null)
			{
				Log.Message("physics intersection info: point: ({0} {1} {2}) shape: {3}\n", intersection.Point.x, intersection.Point.y, intersection.Point.z, shape.TypeName);
			}
		}
		
	}
}

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:下面的例子显示了如何得到交点(vec3)汽缸两点之间的一个障碍。我们会做以下:

1. Create an instance of the ObstacleBox class on the application initialization.在应用程序初始化时创建ObstacleBox类的实例。
2. Define two points (p1 and p2) that specify the beginning and the end of the cylinder.定义两个点(p1和p2),指定开始和结束的缸。
3. Create an instance of the GameIntersection class to get the intersection point coordinates.创建GameIntersection类的实例以获得交点坐标。
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实例相交与一个障碍,你可以得到它的名字使用getName()函数或任何其他细节使用相应的功能。

using System;
using System.Collections;
using System.Collections.Generic;
using Unigine;

#region Math Variables
#if UNIGINE_DOUBLE
using Scalar = System.Double;
using Vec3 = Unigine.dvec3;
#else
using Scalar = System.Single;
using Vec3 = Unigine.vec3;
#endif
#endregion

[Component(PropertyGuid = "AUTOGENERATED_GUID")] // <-- this line is generated automatically for a new component
public class Intersections : Component
{

	// define an obstacle box and game intersection instance
	ObstacleBox obstacleBox;
	GameIntersection gi;

	// parameters of the virtual cylinder defining the volume
	// inside which to check for intersections
	float radius = 1.0f;		// radius of the cylinder
	vec3 p1 = new vec3(0, -3.0f, 3.0f);	// starting point of the ray
	vec3 p2 = new vec3(0, 3.0f, 3.0f);	// ending point of the ray

	private void Init()
	{

		// initialize the obstacle box and specify the name
		obstacleBox = new ObstacleBox(new vec3(1.0f));
		obstacleBox.Name = "main_obstacle";
		
		// initialize the game intersection object
		gi = new GameIntersection();

		// enable the visualizer
		Visualizer.Enabled = true;

	}

	private void Update()
	{

		// make the obstacle box move inside and outside the game intersection area
		Vec3 new_pos = new Vec3(0,0,2 + MathLib.Sin(Game.Time));
		obstacleBox.WorldPosition = new_pos;
		Visualizer.RenderPoint3D(new_pos, 0.15f, vec4.MAGENTA);

		// calculate the cylinder height (equals to the distance between the starting and ending points)
		Visualizer.RenderPoint3D(p1, 0.15f, vec4.BLUE);
		Visualizer.RenderPoint3D(p2, 0.15f, vec4.YELLOW);

		// create an instance of the GameIntersection class
		Obstacle obstacle = Game.GetIntersection(p1, p2, radius, 1, gi);

		//visualize the cylinder that represents the game intersection area
		Visualizer.RenderCylinder(radius, (p2-p1).Length, MathLib.SetTo(p1 + (p2 - p1) / 2, p2, vec3.UP, MathLib.AXIS.Z), vec4.WHITE);
		
		// check if the intersection of the cylinder with the obstacle has occurred
		if (obstacle != null)
		{
			obstacle.RenderVisualizer();
			Log.Message("The name of the obstacle is: {0} \n", obstacle.Name);
		}
	}

}