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# ??????????????

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1. ## The problem with temporary variable

hi guys! http://www.gamedev.net/page/resources/_/technical/math-and-physics/a-verlet-based-approach-for-2d-game-physics-r2714 I read it and decided to finish a bit for themselves. In general, the essence of what I needed was a regular polygon? ????? ???? ? ???, ??? ????? ??? ?????????? ????????????? By the topography object is specified vertices and edges, respectively, as follows:For example vertex created so: Vertex* V1 = new Vertex( this, X , Y );   and the face, say between two vertices as follows: new Edge( this, V1, V2, true );   P.S fourth parameter is responsible for whether to participate in the face of conflict (ie, whether the outside of the face shape, or it will be framed) Suppose that's to create a simple rectangle:???????? ??? ????????? ???????? ???????? ????????????????:   void PhysicsBody::CreateBox( int X, int Y, int Width, int Height ) { Vertex* V1 = new Vertex( this, X , Y ); Vertex* V2 = new Vertex( this, X + Width, Y ); Vertex* V3 = new Vertex( this, X + Width, Y + Height ); Vertex* V4 = new Vertex( this, X , Y + Height ); new Edge( this, V1, V2, true ); new Edge( this, V2, V3, true ); new Edge( this, V3, V4, true ); new Edge( this, V4, V1, true ); new Edge( this, V1, V3, false ); new Edge( this, V2, V4, false ); }   Similarly, I added a method to create a regular polygon: void PhysicsBody::CreateCircle(int X, int Y, int r, int n) { Vertex * V = new Vertex[n]; float a=0.0; Vertex * V1 = new Vertex( this, X , Y ); for (int i=0; i<n; i++) { Vertex * V1 = new Vertex( this, X + r*std::cos(a*PI/180.0f), Y + r*std::sin(a*PI/180.0f)); V[i] = *V1; a+=360.0f/n; } new Edge( this, &V[n-1], &V[0], true ); for (int i=0; i<n-1; i++) new Edge( this, &V[i], &V[i+1], true ); for (int i=0; i<n; i++) new Edge( this, V1, &V[i], false ); //delete(V); }   And here's the problem, if the vertices of creating, describing each, then all would be OK, but here's a situation where I need to, say, 40-angle polygon, I will not each node individually prescribe ..It turns out that, for some reason, remembering addresses are not the top, when I click the mouse button, the polygon is created, but the top is not just tied to its faces and trite fall down attached was only one vertex, the central Vertex * V1 = new Vertex( this, X , Y ); All vertices and edges are stored in the respective arrays.description of the basic structures, ie, faces, vertices and body: #ifndef __PHYSICS_H__ #define __PHYSICS_H__ #ifdef _WIN32 #include <windows.h> #endif #include <GL/glut.h> #include <math.h> #include <iostream> #include "Vector.h" #define MAX_BODIES 2048 //Maximum body/vertex/edgecount the physics simulation can handle #define MAX_VERTICES 5096 #define MAX_EDGES 5096 #define MAX_BODY_VERTICES 64 //Maximum body/edge count a body can contain #define MAX_BODY_EDGES 64 #define PI 3.14159 struct PhysicsBody; //Prototypes struct Vertex { Vec2 Position; Vec2 OldPosition; Vec2 Acceleration; PhysicsBody* Parent; Vertex( PhysicsBody* Body, float PosX, float PosY ); Vertex(){}; }; struct Edge; class Physics { Vec2 Gravity; //Most of this should be clear after reading the article int BodyCount; int VertexCount; int EdgeCount; Vertex* Vertices[ MAX_VERTICES ]; Edge* Edges [ MAX_EDGES ]; PhysicsBody* Bodies [ MAX_BODIES ]; float Timestep; int Iterations; void UpdateForces(); void UpdateVerlet(); void UpdateEdges (); void IterateCollisions(); bool DetectCollision( PhysicsBody* B1, PhysicsBody* B2 ); void ProcessCollision(); float IntervalDistance( float MinA, float MaxA, float MinB, float MaxB ); bool BodiesOverlap( PhysicsBody* B1, PhysicsBody* B2 ); //Used for optimization to test if the bounding boxes of two bodies overlap struct { float Depth; Vec2 Normal; Edge* E; Vertex* V; } CollisionInfo; public: void Update(); void Render(); void AddBody ( PhysicsBody* Body ); void AddEdge ( Edge* E ); void AddVertex( Vertex* V ); Vertex* FindVertex( int X, int Y ); Physics( float GravitationX = 0.0f, float GravitationY = 0.0f, int pIterations = 1 ) : BodyCount( 0 ), VertexCount( 0 ), EdgeCount( 0 ), Gravity( Vec2( GravitationX, GravitationY ) ), Iterations( pIterations ), Timestep( 1.0f ) {} }; struct PhysicsBody { Vec2 Center; //Center of mass int MinX, MinY, MaxX, MaxY; //Min/max coordinates of the bounding box int VertexCount; int EdgeCount; Vertex* Vertices[ MAX_BODY_VERTICES ]; Edge* Edges [ MAX_BODY_EDGES ]; PhysicsBody(); void AddEdge ( Edge* E ); void AddVertex( Vertex* V ); void ProjectToAxis( Vec2& Axis, float& Min, float& Max ); void CalculateCenter(); //Calculates the venter of mass void CreateBox( int X, int Y, int Width, int Height ); void CreateCircle(int X, int Y, int r, int n); }; struct Edge { Vertex* V1; Vertex* V2; float Length; int Boundary; //Value used for optimization - see Physics::DetectCollision for more information PhysicsBody* Parent; Edge( PhysicsBody* Body, Vertex* pV1, Vertex* pV2, int pBoundary = true ); }; #endif   actually referred to add components just add them to the array   void Physics::AddBody( PhysicsBody* Body ) { Bodies[ BodyCount++ ] = Body; } void Physics::AddVertex( Vertex* V ) { Vertices[ VertexCount++ ] = V; } void Physics::AddEdge( Edge* E ) { Edges[ EdgeCount++ ] = E; } So appropriate constructors for the components: Edge::Edge( PhysicsBody* Body, Vertex* pV1, Vertex* pV2, int pBoundary ) { V1 = pV1; V2 = pV2; Length = ( pV2->Position - pV1->Position ).Length(); Boundary = pBoundary; Parent = Body; Body->AddEdge( this ); World.AddEdge( this ); } Vertex::Vertex( PhysicsBody* Body, float PosX, float PosY ) { Position = Vec2( PosX, PosY ); OldPosition = Vec2( PosX, PosY ); Parent = Body; Body->AddVertex( this ); World.AddVertex( this ); } PhysicsBody::PhysicsBody() { VertexCount = EdgeCount = 0; World.AddBody( this ); } How do I solve the problem with falling vertices? P.S demo: http://yadi.sk/d/Qg0_nZ7h1lOXC
2. ## ??????????????

C ????? ????? ??????! ? ????? ????? ??????! ? ?????? ????? ? ??????????!
3. ## Verlet physics

Thanks, but it's not work true
4. ## ??????????????

??????? ?????? ?????? ?? ??????? ????? ? ?????, ?? ???, ?? ??????? ??? ????? ????? ???????? ??? ? ??????? 50 ??? ? ?????, ?? ??????? ???????? ? ???????? ? ?????, ?? ??????? ????????". ?????????? ??? ? ??????? ?? ???????.
5. ## A Verlet based approach for 2D game physics

How to add friction to this?
6. ## Verlet physics

Hi guys! I was read this article on this site [url="http://www.gamedev.net/page/resources/_/technical/math-and-physics/a-verlet-based-approach-for-2d-game-physics-r2714"]http://www.gamedev.n...e-physics-r2714[/url] And I wondered, what if upgrade it for experiment? i downloaded it and decided to add friction. But I did not understand how to do it correctly. We can replace the speed of this[b] [color=#ff0000]-k*N+OldVelocity[/color][/b][color=#ff0000];[/color] [color=#000000]where N as I understood the normalized velocity (well, more multiplied by -1 is not?)[/color] Well, add a small fix that would not work, that the infinite is force the body begins to move in the opposite direction [b][color=#ff0000]VelNew = max(-k*N+OldVelocity, 0.0f)[/color][/b] how to modify this method (if not this one?) to get the friction? [source lang="cpp"]void Physics::UpdateVerlet() { //????????? ????????? ?????? for( int I = 0; I < VertexCount; I++ ) { Vertex& V = *Vertices[ I ]; Vec2 OldPosition = V.Position; V.Position += V.Position-V.OldPosition + V.Acceleration*Timestep*Timestep; V.OldPosition = OldPosition; } }[/source]
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