C# Vec2.Set方法代码示例

		/// <summary>
		/// This constructor sets the body definition default values.
		/// </summary>
		public BodyDef()
		{
			MassData = new MassData();
			MassData.Center.SetZero();
			MassData.Mass = 0.0f;
			MassData.I = 0.0f;
			UserData = null;
			Position = new Vec2();
			Position.Set(0.0f, 0.0f);
			Angle = 0.0f;
			LinearDamping = 0.0f;
			AngularDamping = 0.0f;
			AllowSleep = true;
			IsSleeping = false;
			FixedRotation = false;
			IsBullet = false;
		}

        public static Vec2 ComputeCentroid(Vec2[] vs, int count)
        {
            Box2DXDebug.Assert(count >= 2);

            Vec2 c = new Vec2(); c.Set(0.0f, 0.0f);
            float area = 0.0f;

            // pRef is the reference point for forming triangles.
            // It's location doesn't change the result (except for rounding error).
            Vec2 pRef = new Vec2(0.0f, 0.0f);
            #if O
            // This code would put the reference point inside the polygon.
            for (int i = 0; i < count; ++i)
            {
                pRef += vs[i];
            }
            pRef *= 1.0f / count;
            #endif

            const float inv3 = 1.0f / 3.0f;

            for (int i = 0; i < count; ++i)
            {
                // Triangle vertices.
                Vec2 p1 = pRef;
                Vec2 p2 = vs[i];
                Vec2 p3 = i + 1 < count ? vs[i + 1] : vs[0];

                Vec2 e1 = p2 - p1;
                Vec2 e2 = p3 - p1;

                float D = Vec2.Cross(e1, e2);

                float triangleArea = 0.5f * D;
                area += triangleArea;

                // Area weighted centroid
                c += triangleArea * inv3 * (p1 + p2 + p3);
            }

            // Centroid
            Box2DXDebug.Assert(area > Settings.FLT_EPSILON);
            c *= 1.0f / area;
            return c;
        }

		public static Vec2 operator -(Vec2 v1, Vec2 v2)
		{
			Vec2 v = new Vec2();
			v.Set(v1.X - v2.X, v1.Y - v2.Y);
			return v;
		}

		public override void ComputeMass(out MassData massData)
		{
			// Polygon mass, centroid, and inertia.
			// Let rho be the polygon density in mass per unit area.
			// Then:
			// mass = rho * int(dA)
			// centroid.x = (1/mass) * rho * int(x * dA)
			// centroid.y = (1/mass) * rho * int(y * dA)
			// I = rho * int((x*x + y*y) * dA)
			//
			// We can compute these integrals by summing all the integrals
			// for each triangle of the polygon. To evaluate the integral
			// for a single triangle, we make a change of variables to
			// the (u,v) coordinates of the triangle:
			// x = x0 + e1x * u + e2x * v
			// y = y0 + e1y * u + e2y * v
			// where 0 <= u && 0 <= v && u + v <= 1.
			//
			// We integrate u from [0,1-v] and then v from [0,1].
			// We also need to use the Jacobian of the transformation:
			// D = cross(e1, e2)
			//
			// Simplification: triangle centroid = (1/3) * (p1 + p2 + p3)
			//
			// The rest of the derivation is handled by computer algebra.

			Box2DXDebug.Assert(_vertexCount >= 3);

			Vec2 center = new Vec2();
			center.Set(0.0f, 0.0f);
			float area = 0.0f;
			float I = 0.0f;

			// pRef is the reference point for forming triangles.
			// It's location doesn't change the result (except for rounding error).
			Vec2 pRef = new Vec2(0.0f, 0.0f);

#if O
			// This code would put the reference point inside the polygon.
			for (int i = 0; i < _vertexCount; ++i)
			{
				pRef += _vertices[i];
			}
			pRef *= 1.0f / count;
#endif

			float k_inv3 = 1.0f / 3.0f;

			for (int i = 0; i < _vertexCount; ++i)
			{
				// Triangle vertices.
				Vec2 p1 = pRef;
				Vec2 p2 = _vertices[i];
				Vec2 p3 = i + 1 < _vertexCount ? _vertices[i + 1] : _vertices[0];

				Vec2 e1 = p2 - p1;
				Vec2 e2 = p3 - p1;

				float D = Vec2.Cross(e1, e2);

				float triangleArea = 0.5f * D;
				area += triangleArea;

				// Area weighted centroid
				center += triangleArea * k_inv3 * (p1 + p2 + p3);

				float px = p1.X, py = p1.Y;
				float ex1 = e1.X, ey1 = e1.Y;
				float ex2 = e2.X, ey2 = e2.Y;

				float intx2 = k_inv3 * (0.25f * (ex1 * ex1 + ex2 * ex1 + ex2 * ex2) + (px * ex1 + px * ex2)) + 0.5f * px * px;
				float inty2 = k_inv3 * (0.25f * (ey1 * ey1 + ey2 * ey1 + ey2 * ey2) + (py * ey1 + py * ey2)) + 0.5f * py * py;

				I += D * (intx2 + inty2);
			}

			// Total mass
			massData.Mass = _density * area;

			// Center of mass
			Box2DXDebug.Assert(area > Common.Settings.FLT_EPSILON);
			center *= 1.0f / area;
			massData.Center = center;

			// Inertia tensor relative to the local origin.
			massData.I = _density * I;
		}

 /// <summary>
 /// This constructor sets the body definition default values.
 /// </summary>
 public BodyDef()
 {
     UserData = null;
     Position = new Vec2();
     Position.Set(0.0f, 0.0f);
     Angle = 0.0f;
     LinearVelocity = new Vec2(0f, 0f);
     AngularVelocity = 0.0f;
     LinearDamping = 0.0f;
     AngularDamping = 0.0f;
     AllowSleep = true;
     IsSleeping = false;
     FixedRotation = false;
     IsBullet = false;
 }

		private void MoveAABB(ref AABB aabb)
		{
			Vec2 d = new Vec2();
			d.X = Box2DXMath.Random(-0.5f, 0.5f);
			d.Y = Box2DXMath.Random(-0.5f, 0.5f);
			//d.x = 2.0f;
			//d.y = 0.0f;
			aabb.LowerBound += d;
			aabb.UpperBound += d;

			Vec2 c0 = 0.5f * (aabb.LowerBound + aabb.UpperBound);
			Vec2 min = new Vec2(); min.Set(-k_extent, 0.0f);
			Vec2 max = new Vec2(); max.Set(k_extent, 2.0f * k_extent);
			Vec2 c = Box2DXMath.Clamp(c0, min, max);

			aabb.LowerBound += c - c0;
			aabb.UpperBound += c - c0;
		}

		private void GetRandomAABB(ref AABB aabb)
		{
			Vec2 w = new Vec2(); w.Set(k_width, k_width);
			aabb.LowerBound.X = Box2DXMath.Random(-k_extent, k_extent);
			aabb.LowerBound.Y = Box2DXMath.Random(0.0f, 2.0f * k_extent);
			aabb.UpperBound = aabb.LowerBound + w;
		}

        public Test()
        {
            Vec2 gravity = new Vec2();
            gravity.Set(0.0f, -10.0f);
            bool doSleep = true;
            _world = new World(gravity, doSleep);
            _bomb = null;
            _textLine = 30;
            _mouseJoint = null;
            _pointCount = 0;

            _destructionListener.test = this;
            _world.SetDestructionListener(_destructionListener);
            _world.SetContactListener(this);
            _world.SetDebugDraw(_debugDraw);

            _bombSpawning = false;

            _stepCount = 0;

            BodyDef bodyDef = new BodyDef();
            _groundBody = _world.CreateBody(bodyDef);
        }

		/// <summary>
		/// Perform the cross product on a scalar and a vector. 
		/// In 2D this produces a vector.
		/// </summary>
		public static Vec2 Cross(float s, Vec2 a)
		{
			Vec2 v = new Vec2();
			v.Set(-s * a.Y, s * a.X);
			return v;
		}

		public void MouseDown(Vec2 p)
		{
			if (_mouseJoint != null)
			{
				return;
			}

			// Make a small box.
			AABB aabb = new AABB();
			Vec2 d = new Vec2();
			d.Set(0.001f, 0.001f);
			aabb.LowerBound = p - d;
			aabb.UpperBound = p + d;

			// Query the world for overlapping shapes.
			int k_maxCount = 10;
			Fixture[] shapes = new Fixture[k_maxCount];
			int count = _world.Query(aabb, shapes, k_maxCount);
			Body body = null;
			for (int i = 0; i < count; ++i)
			{
				Body shapeBody = shapes[i].Body;
				if (shapeBody.IsStatic() == false && shapeBody.GetMass() > 0.0f)
				{
					bool inside = shapes[i].TestPoint(p);
					if (inside)
					{
						body = shapes[i].Body;
						break;
					}
				}
			}

			if (body != null)
			{
				MouseJointDef md = new MouseJointDef();
				md.Body1 = _world.GetGroundBody();
				md.Body2 = body;
				md.Target = p;
#if TARGET_FLOAT32_IS_FIXED
				md.MaxForce = (body.GetMass() < 16.0f)? 
					(1000.0f * body.GetMass()) : 16000.0f;
#else
				md.MaxForce = 1000.0f * body.GetMass();
#endif
				_mouseJoint = (MouseJoint)_world.CreateJoint(md);
				body.WakeUp();
			}
		}

		public Test()
		{
			_worldAABB = new AABB();
			_worldAABB.LowerBound.Set(-200.0f, -100.0f);
			_worldAABB.UpperBound.Set(200.0f, 200.0f);
			Vec2 gravity = new Vec2();
			gravity.Set(0.0f, -10.0f);
			bool doSleep = true;
			_world = new World(_worldAABB, gravity, doSleep);
			_bomb = null;
			_textLine = 30;
			_mouseJoint = null;
			_pointCount = 0;

			_destructionListener.test = this;
			_boundaryListener.test = this;
			//_contactListener.test = this;
			_world.SetDestructionListener(_destructionListener);
			_world.SetBoundaryListener(_boundaryListener);
			//_world.SetContactListener(_contactListener);
			_world.SetDebugDraw(_debugDraw);
		}

		private void DrawDebugData()
		{
			if (_debugDraw == null)
			{
				return;
			}

			DebugDraw.DrawFlags flags = _debugDraw.Flags;

			if ((flags & DebugDraw.DrawFlags.Shape) != 0)
			{
				bool core = (flags & DebugDraw.DrawFlags.CoreShape) == DebugDraw.DrawFlags.CoreShape;

				for (Body b = _bodyList; b != null; b = b.GetNext())
				{
					XForm xf = b.GetXForm();
					for (Shape s = b.GetShapeList(); s != null; s = s.GetNext())
					{
						if (b.IsStatic())
						{
							DrawShape(s, xf, new Color(0.5f, 0.9f, 0.5f), core);
						}
						else if (b.IsSleeping())
						{
							DrawShape(s, xf, new Color(0.5f, 0.5f, 0.9f), core);
						}
						else
						{
							DrawShape(s, xf, new Color(0.9f, 0.9f, 0.9f), core);
						}
					}
				}
			}

			if ((flags & DebugDraw.DrawFlags.Joint) != 0)
			{
				for (Joint j = _jointList; j != null; j = j.GetNext())
				{
					if (j.GetType() != JointType.MouseJoint)
					{
						DrawJoint(j);
					}
				}
			}

			if ((flags & DebugDraw.DrawFlags.Pair) != 0)
			{
				BroadPhase bp = _broadPhase;
				Vec2 invQ = new Vec2();
				invQ.Set(1.0f / bp._quantizationFactor.X, 1.0f / bp._quantizationFactor.Y);
				Color color = new Color(0.9f, 0.9f, 0.3f);

				for (int i = 0; i < PairManager.TableCapacity; ++i)
				{
					ushort index = bp._pairManager._hashTable[i];
					while (index != PairManager.NullPair)
					{
						Pair pair = bp._pairManager._pairs[index];
						Proxy p1 = bp._proxyPool[pair.ProxyId1];
						Proxy p2 = bp._proxyPool[pair.ProxyId2];

						AABB b1 = new AABB(), b2 = new AABB();
						b1.LowerBound.X = bp._worldAABB.LowerBound.X + invQ.X * bp._bounds[0][p1.LowerBounds[0]].Value;
						b1.LowerBound.Y = bp._worldAABB.LowerBound.Y + invQ.Y * bp._bounds[1][p1.LowerBounds[1]].Value;
						b1.UpperBound.X = bp._worldAABB.LowerBound.X + invQ.X * bp._bounds[0][p1.UpperBounds[0]].Value;
						b1.UpperBound.Y = bp._worldAABB.LowerBound.Y + invQ.Y * bp._bounds[1][p1.UpperBounds[1]].Value;
						b2.LowerBound.X = bp._worldAABB.LowerBound.X + invQ.X * bp._bounds[0][p2.LowerBounds[0]].Value;
						b2.LowerBound.Y = bp._worldAABB.LowerBound.Y + invQ.Y * bp._bounds[1][p2.LowerBounds[1]].Value;
						b2.UpperBound.X = bp._worldAABB.LowerBound.X + invQ.X * bp._bounds[0][p2.UpperBounds[0]].Value;
						b2.UpperBound.Y = bp._worldAABB.LowerBound.Y + invQ.Y * bp._bounds[1][p2.UpperBounds[1]].Value;

						Vec2 x1 = 0.5f * (b1.LowerBound + b1.UpperBound);
						Vec2 x2 = 0.5f * (b2.LowerBound + b2.UpperBound);

						_debugDraw.DrawSegment(x1, x2, color);

						index = pair.Next;
					}
				}
			}

			if ((flags & DebugDraw.DrawFlags.Aabb) != 0)
			{
				BroadPhase bp = _broadPhase;
				Vec2 worldLower = bp._worldAABB.LowerBound;
				Vec2 worldUpper = bp._worldAABB.UpperBound;

				Vec2 invQ = new Vec2();
				invQ.Set(1.0f / bp._quantizationFactor.X, 1.0f / bp._quantizationFactor.Y);
				Color color = new Color(0.9f, 0.3f, 0.9f);
				for (int i = 0; i < Settings.MaxProxies; ++i)
				{
					Proxy p = bp._proxyPool[i];
					if (p.IsValid == false)
					{
						continue;
					}

					AABB b = new AABB();
					b.LowerBound.X = worldLower.X + invQ.X * bp._bounds[0][p.LowerBounds[0]].Value;
//.........这里部分代码省略.........

        public Dominos()
        {
            Body b1;
            {
                PolygonShape shape = new PolygonShape();
                shape.SetAsEdge(new Vec2(-40.0f, 0.0f), new Vec2(40.0f, 0.0f));

                BodyDef bd = new BodyDef();
                b1 = _world.CreateBody(bd);
                b1.CreateFixture(shape,0);
            }

            {
                PolygonShape shape = new PolygonShape();
                shape.SetAsBox(6.0f, 0.25f);

                BodyDef bd = new BodyDef();
                bd.Position.Set(-1.5f, 10.0f);
                Body ground = _world.CreateBody(bd);
                ground.CreateFixture(shape,0);
            }

            {
                PolygonShape shape = new PolygonShape();
                shape.SetAsBox(0.1f, 1.0f);

                FixtureDef fd = new FixtureDef();
                fd.Shape = shape;
                fd.Density = 20.0f;
                fd.Friction = 0.1f;

                for (int i = 0; i < 10; ++i)
                {
                    BodyDef bd = new BodyDef();
                    bd.Position.Set(-6.0f + 1.0f * i, 11.25f);
                    Body body = _world.CreateBody(bd);
                    body.CreateFixture(fd);
                }
            }

            {
                PolygonShape shape = new PolygonShape();
                shape.SetAsBox(7.0f, 0.25f, Vec2.Zero, 0.3f);

                BodyDef bd = new BodyDef();
                bd.Position.Set(1.0f, 6.0f);
                Body ground = _world.CreateBody(bd);
                ground.CreateFixture(shape,0);
            }

            Body b2;
            {
                PolygonShape shape = new PolygonShape();
                shape.SetAsBox(0.25f, 1.5f);

                BodyDef bd = new BodyDef();
                bd.Position.Set(-7.0f, 4.0f);
                 b2 = _world.CreateBody(bd);
                b2.CreateFixture(shape,0);
            }

            Body b3;
            {
                PolygonShape shape = new PolygonShape();
                shape.SetAsBox(6.0f, 0.125f);

                BodyDef bd = new BodyDef();
                bd.Position.Set(-0.9f, 1.0f);
                bd.Angle = -0.15f;

                b3 = _world.CreateBody(bd);
                b3.CreateFixture(shape, 10.0f);
            }

            RevoluteJointDef jd = new RevoluteJointDef();
            Vec2 anchor = new Vec2();

            anchor.Set(-2.0f, 1.0f);
            jd.Initialize(b1, b3, anchor);
            jd.CollideConnected = true;
            _world.CreateJoint(jd);

            Body b4;
            {
                PolygonShape shape = new PolygonShape();
                shape.SetAsBox(0.25f, 0.25f);

                BodyDef bd  = new BodyDef();
                bd.Position.Set(-10.0f, 15.0f);
                b4 = _world.CreateBody(bd);
                b4.CreateFixture(shape, 10.0f);
            }

            anchor.Set(-7.0f, 15.0f);
            jd.Initialize(b2, b4, anchor);
            _world.CreateJoint(jd);

            Body b5;
            {
                BodyDef bd = new BodyDef();
//.........这里部分代码省略.........

        public void MouseDown(Vec2 p)
        {
            _mouseWorld = p;

            if (_mouseJoint != null)
            {
                return;
            }

            // Make a small box.
            AABB aabb = new AABB();
            Vec2 d = new Vec2();
            d.Set(0.001f, 0.001f);
            aabb.LowerBound = p - d;
            aabb.UpperBound = p + d;

            // Query the world for overlapping shapes.
            MyQueryCallback callback = new MyQueryCallback(p);
            _world.QueryAABB(callback, aabb);

            if (callback._fixture != null)
            {
                Body body = callback._fixture.GetBody();
                MouseJointDef md = new MouseJointDef();
                md.Body1 = _groundBody;
                md.Body2 = body;
                md.Target = p;
            #if TARGET_FLOAT32_IS_FIXED
                md.maxForce = (body->GetMass() < 16.0)? (1000.0f * body->GetMass()) : float32(16000.0);
            #else
                md.MaxForce = 1000.0f * body.GetMass();
            #endif
                _mouseJoint = (MouseJoint)_world.CreateJoint(md);
                body.WakeUp();
            }
        }

        /// <summary>
        /// Create an empty Box2D world.
        /// </summary>
        private World CreateBox2DWorld()
        {
			AABB worldAABB = new AABB();
			worldAABB.LowerBound.Set(_simParams._lowerBoundPhysics.X, _simParams._lowerBoundPhysics.Y);
			worldAABB.UpperBound.Set(_simParams._upperBoundPhysics.X, _simParams._upperBoundPhysics.Y);
			Vec2 gravity = new Vec2();
			gravity.Set(0.0f, _simParams._gravity);
			bool doSleep = false;
			World world = new World(worldAABB, gravity, doSleep);
            return world;
        }