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  • Implementing a wrapping wire (like the Worms Ninja Rope) in a 2D physics engine

    - by Andrew Russell
    I've been trying out some rope-physics recently, and I've found that the "standard" solution - making a rope from a series of objects strung together with springs or joints - is unsatisfying. Especially when rope swinging is relevant to gameplay. I don't really care about a rope's ability to wrap up or sag (this can be faked for visuals anyway). For gameplay, what is important is the ability for the rope to wrap around the environment and then subsequently unwrap. It doesn't even have to behave like rope - a "wire" made up of straight line segments would do. Here's an illustration: This is very similar to the "Ninja Rope" from the game Worms. Because I'm using a 2D physics engine - my environment is made up of 2D convex polygons. (Specifically I am using SAT in Farseer.) So my question is this: How would you implement the "wrapping" effect? It seems pretty obvious that the wire will be made up of a series of line segments that "split" and "join". And the final (active) segment of that line, where the moving object attaches, will be a fixed-length joint. But what is the maths / algorithm involved for determining when and where the active line segment needs to be split? And when it needs to be joined with the previous segment? (Previously this question also asked about doing this for a dynamic environment - I've decided to split that off into other questions.)

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  • Converting 2D Physics to 3D.

    - by static void main
    I'm new to game physics and I am trying to adapt a simple 2D ball simulation for a 3D simulation with the Java3D library. I have this problem: Two things: 1) I noted down the values generated by the engine: X/Y are too high and minX/minY/maxY/maxX values are causing trouble. Sometimes the balls are drawing but not moving Sometimes they are going out of the panel Sometimes they're moving on little area Sometimes they just stick at one place... 2) I'm unable to select/define/set the default correct/suitable values considering the 3D graphics scaling/resolution while they are set with respect to 2D screen coordinates, that is my only problem. Please help. This is the code: public class Ball extends GameObject { private float x, y; // Ball's center (x, y) private float speedX, speedY; // Ball's speed per step in x and y private float radius; // Ball's radius // Collision detected by collision detection and response algorithm? boolean collisionDetected = false; // If collision detected, the next state of the ball. // Otherwise, meaningless. private float nextX, nextY; private float nextSpeedX, nextSpeedY; private static final float BOX_WIDTH = 640; private static final float BOX_HEIGHT = 480; /** * Constructor The velocity is specified in polar coordinates of speed and * moveAngle (for user friendliness), in Graphics coordinates with an * inverted y-axis. */ public Ball(String name1,float x, float y, float radius, float speed, float angleInDegree, Color color) { this.x = x; this.y = y; // Convert velocity from polar to rectangular x and y. this.speedX = speed * (float) Math.cos(Math.toRadians(angleInDegree)); this.speedY = speed * (float) Math.sin(Math.toRadians(angleInDegree)); this.radius = radius; } public void move() { if (collisionDetected) { // Collision detected, use the values computed. x = nextX; y = nextY; speedX = nextSpeedX; speedY = nextSpeedY; } else { // No collision, move one step and no change in speed. x += speedX; y += speedY; } collisionDetected = false; // Clear the flag for the next step } public void collideWith() { // Get the ball's bounds, offset by the radius of the ball float minX = 0.0f + radius; float minY = 0.0f + radius; float maxX = 0.0f + BOX_WIDTH - 1.0f - radius; float maxY = 0.0f + BOX_HEIGHT - 1.0f - radius; double gravAmount = 0.9811111f; double gravDir = (90 / 57.2960285258); // Try moving one full step nextX = x + speedX; nextY = y + speedY; System.out.println("In serializedBall in collision."); // If collision detected. Reflect on the x or/and y axis // and place the ball at the point of impact. if (speedX != 0) { if (nextX > maxX) { // Check maximum-X bound collisionDetected = true; nextSpeedX = -speedX; // Reflect nextSpeedY = speedY; // Same nextX = maxX; nextY = (maxX - x) * speedY / speedX + y; // speedX non-zero } else if (nextX < minX) { // Check minimum-X bound collisionDetected = true; nextSpeedX = -speedX; // Reflect nextSpeedY = speedY; // Same nextX = minX; nextY = (minX - x) * speedY / speedX + y; // speedX non-zero } } // In case the ball runs over both the borders. if (speedY != 0) { if (nextY > maxY) { // Check maximum-Y bound collisionDetected = true; nextSpeedX = speedX; // Same nextSpeedY = -speedY; // Reflect nextY = maxY; nextX = (maxY - y) * speedX / speedY + x; // speedY non-zero } else if (nextY < minY) { // Check minimum-Y bound collisionDetected = true; nextSpeedX = speedX; // Same nextSpeedY = -speedY; // Reflect nextY = minY; nextX = (minY - y) * speedX / speedY + x; // speedY non-zero } } speedX += Math.cos(gravDir) * gravAmount; speedY += Math.sin(gravDir) * gravAmount; } public float getSpeed() { return (float) Math.sqrt(speedX * speedX + speedY * speedY); } public float getMoveAngle() { return (float) Math.toDegrees(Math.atan2(speedY, speedX)); } public float getRadius() { return radius; } public float getX() { return x; } public float getY() { return y; } public void setX(float f) { x = f; } public void setY(float f) { y = f; } } Here's how I'm drawing the balls: public class 3DMovingBodies extends Applet implements Runnable { private static final int BOX_WIDTH = 800; private static final int BOX_HEIGHT = 600; private int currentNumBalls = 1; // number currently active private volatile boolean playing; private long mFrameDelay; private JFrame frame; private int currentFrameRate; private Ball[] ball = new Ball[currentNumBalls]; private Random rand; private Sphere[] sphere = new Sphere[currentNumBalls]; private Transform3D[] trans = new Transform3D[currentNumBalls]; private TransformGroup[] objTrans = new TransformGroup[currentNumBalls]; public 3DMovingBodies() { rand = new Random(); float angleInDegree = rand.nextInt(360); setLayout(new BorderLayout()); GraphicsConfiguration config = SimpleUniverse .getPreferredConfiguration(); Canvas3D c = new Canvas3D(config); add("Center", c); ball[0] = new Ball(0.5f, 0.0f, 0.5f, 0.4f, angleInDegree, Color.yellow); // ball[1] = new Ball(1.0f, 0.0f, 0.25f, 0.8f, angleInDegree, // Color.yellow); // ball[2] = new Ball(0.0f, 1.0f, 0.15f, 0.11f, angleInDegree, // Color.yellow); trans[0] = new Transform3D(); // trans[1] = new Transform3D(); // trans[2] = new Transform3D(); sphere[0] = new Sphere(0.5f); // sphere[1] = new Sphere(0.25f); // sphere[2] = new Sphere(0.15f); // Create a simple scene and attach it to the virtual universe BranchGroup scene = createSceneGraph(); SimpleUniverse u = new SimpleUniverse(c); u.getViewingPlatform().setNominalViewingTransform(); u.addBranchGraph(scene); startSimulation(); } public BranchGroup createSceneGraph() { // Create the root of the branch graph BranchGroup objRoot = new BranchGroup(); for (int i = 0; i < currentNumBalls; i++) { // Create a simple shape leaf node, add it to the scene graph. objTrans[i] = new TransformGroup(); objTrans[i].setCapability(TransformGroup.ALLOW_TRANSFORM_WRITE); Transform3D pos1 = new Transform3D(); pos1.setTranslation(randomPos()); objTrans[i].setTransform(pos1); objTrans[i].addChild(sphere[i]); objRoot.addChild(objTrans[i]); } BoundingSphere bounds = new BoundingSphere(new Point3d(0.0, 0.0, 0.0), 100.0); Color3f light1Color = new Color3f(1.0f, 0.0f, 0.2f); Vector3f light1Direction = new Vector3f(4.0f, -7.0f, -12.0f); DirectionalLight light1 = new DirectionalLight(light1Color, light1Direction); light1.setInfluencingBounds(bounds); objRoot.addChild(light1); // Set up the ambient light Color3f ambientColor = new Color3f(1.0f, 1.0f, 1.0f); AmbientLight ambientLightNode = new AmbientLight(ambientColor); ambientLightNode.setInfluencingBounds(bounds); objRoot.addChild(ambientLightNode); return objRoot; } public void startSimulation() { playing = true; Thread t = new Thread(this); t.start(); } public void stop() { playing = false; } public void run() { long previousTime = System.currentTimeMillis(); long currentTime = previousTime; long elapsedTime; long totalElapsedTime = 0; int frameCount = 0; while (true) { currentTime = System.currentTimeMillis(); elapsedTime = (currentTime - previousTime); // elapsed time in // seconds totalElapsedTime += elapsedTime; if (totalElapsedTime > 1000) { currentFrameRate = frameCount; frameCount = 0; totalElapsedTime = 0; } for (int i = 0; i < currentNumBalls; i++) { ball[i].move(); ball[i].collideWith(); drawworld(); } try { Thread.sleep(88); } catch (Exception e) { e.printStackTrace(); } previousTime = currentTime; frameCount++; } } public void drawworld() { for (int i = 0; i < currentNumBalls; i++) { printTG(objTrans[i], "SteerTG"); trans[i].setTranslation(new Vector3f(ball[i].getX(), ball[i].getY(), 0.0f)); objTrans[i].setTransform(trans[i]); } } private Vector3f randomPos() /* * Return a random position vector. The numbers are hardwired to be within * the confines of the box. */ { Vector3f pos = new Vector3f(); pos.x = rand.nextFloat() * 5.0f - 2.5f; // -2.5 to 2.5 pos.y = rand.nextFloat() * 2.0f + 0.5f; // 0.5 to 2.5 pos.z = rand.nextFloat() * 5.0f - 2.5f; // -2.5 to 2.5 return pos; } // end of randomPos() public static void main(String[] args) { System.out.println("Program Started"); 3DMovingBodiesbb = new 3DMovingBodies(); bb.addKeyListener(bb); MainFrame mf = new MainFrame(bb, 600, 400); } }

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  • Dynamic character animation - Using the physics engine or not

    - by Lex Webb
    I'm planning on building a dynamic reactant animation engine for the characters in my 2D Game. I have already built templates for a skeleton based animation system using key frames and interpolation to specify a limbs position at any given moment in time. I am using Farseer physics (an extension of Box2D) in Monogame/XNA in C# My real question lies in how i go about tying this character animation into the physics engine. I have two options: Moving limbs using physics engine - applying a interpolated force to each limb (dynamic body) in order to attempt to get it to its position as donated by the skeleton animation. Moving limbs by simply changing the position of a fixed body - Updating the new position of each limb manually, attempting to take into account physics collisions. Then stepping the physics after the animation to allow for environment interaction. Each of these methods have their distinct advantages and disadvantages. Physics based movement Advantages: Possibly more natural/realistic movement Better interaction with game objects as force applying to objects colliding with characters would be calculated for me. No need to convert to dynamic bodies when reacting to projectiles/death/fighting. Disadvantages: Possible difficulty in calculating correct amount of force to move a limb a certain distance at a constant rate. Underlying character balance system would need to be created that would need to be robust enough to prevent characters falling over at the touch of a feather. Added code complexity and processing time for the above. Static Object movement Advantages: Easy to interpolate movement of limbs between game steps Moving limbs is as simple as applying a rotation to the skeleton bone. Greater control over limbs, wont need to worry about characters falling over as all animation would be pre-defined. Disadvantages: Possible unnatural movement (Depends entirely on my animation skills!) Bad physics collision reactions with physics engine (Dynamic bodies simply slide out of the way of static objects) Need to calculate collisions with physics objects and my limbs myself and apply directional forces to them. Hard to account for slopes/stairs/non standard planes when animating walking/running animations. Need to convert objects to dynamic when reacting to projectile/fighting/death physics objects. The Question! As you can see, i have thought about this extensively, i have also had Google into physics based animation and have found mostly dissertation papers! Which is filling me with sense that it may a lot more advanced than my mathematics skills. My question is mostly subjective based on my findings above/any experience you may have: Which of the above methods should i use when creating my game? I am willing to spend the time to get a physics solution working if you think it would be possible. In the end i want to provide the most satisfying experience for the gamer, as well as a robust and dynamic system i can use to animate pretty much anything i need.

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  • 2D Physics Engine to Handle Shapes Composed of Multiple Densities XNA

    - by Stupac
    The game I'm working on involves shapes that might be composed of multiple materials in a variety of ways. Let's just take for example a wooden rod with and sizable tip of iron or say a block composed of a couple triangles of stone and aluminum and small nugget of gold. The shapes and compositions will change from time to time, so I was wondering what engine I should use and how I might implement this feature? I've looked at Farseer 3, but I'm still trying to decipher the library by reading the source and the samples and wasn't sure if I was barking up the wrong tree. Thanks!

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  • Sharing data between graphics and physics engine in the game?

    - by PolGraphic
    I'm writing the game engine that consists of few modules. Two of them are the graphics engine and the physics engine. I wonder if it's a good solution to share data between them? Two ways (sharing or not) looks like that: Without sharing data GraphicsModel{ //some common for graphics and physics data like position //some only graphic data //like textures and detailed model's verticles that physics doesn't need }; PhysicsModel{ //some common for graphics and physics data like position //some only physics data //usually my physics data contains A LOT more informations than graphics data } engine3D->createModel3D(...); physicsEngine->createModel3D(...); //connect graphics and physics data //e.g. update graphics model's position when physics model's position will change I see two main problems: A lot of redundant data (like two positions for both physics and graphics data) Problem with updating data (I have to manually update graphics data when physics data changes) With sharing data Model{ //some common for graphics and physics data like position }; GraphicModel : public Model{ //some only graphics data //like textures and detailed model's verticles that physics doesn't need }; PhysicsModel : public Model{ //some only physics data //usually my physics data contains A LOT more informations than graphics data } model = engine3D->createModel3D(...); physicsEngine->assingModel3D(&model); //will cast to //PhysicsModel for it's purposes?? //when physics changes anything (like position) in model //(which it treats like PhysicsModel), the position for graphics data //will change as well (because it's the same model) Problems here: physicsEngine cannot create new objects, just "assing" existing ones from engine3D (somehow it looks more anti-independent for me) Casting data in assingModel3D function physicsEngine and graphicsEngine must be careful - they cannot delete data when they don't need them (because second one may need it). But it's rare situation. Moreover, they can just delete the pointer, not the object. Or we can assume that graphicsEngine will delete objects, physicsEngine just pointers to them. Which way is better? Which will produce more problems in the future? I like the second solution more, but I wonder why most graphics and physics engines prefer the first one (maybe because they normally make only graphics or only physics engine and somebody else connect them in the game?). Have they any more hidden pros & contras?

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  • Physics engine that can handle multiple attractors?

    - by brice
    I'm putting together a game that will be played mostly with three dimensional gravity. By that I mean multiple planets/stars/moons behaving realistically, and path plotting and path prediction in the gravity field. I have looked at a variety of physics engines, such as Bullet, tokamak or Newton, but none of them seem to be suitable, as I'd essentially have to re-write the gravity engine in their framework. Do you know of a physics engine that is capable of dealing with multiple bodies all attracted to one another? I don't need scenegraph management, or rendering, just core physics. (collision detection would be a bonus, as would rigid body dynamics). My background is in physics, so I would be able to write an engine that uses Verlet integration or RK4 (or even Euler integration, if I had to) but I'd much rather adapt an off the shelf solution. [edit]: There are some great resources for physics simulation of n-body problems online, and on stackoverflow

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  • 2D soft-body physics engines?

    - by Griffin
    Hi so i've recently learned the SFML graphics library and would like to use or make a non-rigid body 2D physics system to use with it. I have three questions: The definition of rigid body in Box2d is A chunk of matter that is so strong that the distance between any two bits of matter on the chunk is completely constant. And this is exactly what i don't want as i would like to make elastic, deformable, breakable, and re-connection bodies. 1. Are there any simple 2D physics engines, but with these kinds of characteristics out there? preferably free or opensource? 2. If not could i use box2d and work off of it to create it even if it's based on rigid bodies? 3. Finally, if there is a simple physics engine like this, should i go through with the proccess of creating a new one anyway, simply for experience and to enhance physics math knowledge? I feel like it would help if i ever wanted to modify the code of an existing engine, or create a game with really unique physics. Thanks!

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  • Homemaking a 2d soft body physics engine

    - by Griffin
    hey so I've decided to Code my own 2D soft-body physics engine in C++ since apparently none exist and I'm starting only with a general idea/understanding on how physics work and could be simulated: by giving points and connections between points properties such as elasticity, density, mass, shape retention, friction, stickiness, etc. What I want is a starting point: resources and helpful examples/sites that could give me the specifics needed to actually make this such as equations and required physics knowledge. It would be great if anyone out there also would give me their attempts or ideas. finally I was wondering if it was possible to... use the source code of an existing 3D engine such as Bullet and transform it to be 2D based? use the source code of a 2D Rigid body physics engine such as box2d as a starting point?

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  • Homemaking a 2d soft body physics engine

    - by Griffin
    hey so I've decided to Code my own 2D soft-body physics engine in C++ since apparently none exist and I'm starting only with a general idea/understanding on how physics work and could be simulated: by giving points and connections between points properties such as elasticity, density, mass, shape retention, friction, stickiness, etc. What I want is a starting point: resources and helpful examples/sites that could give me the specifics needed to actually make this such as equations and required physics knowledge. It would be great if anyone out there also would give me their attempts or ideas. finally I was wondering if it was possible to... use the source code of an existing 3D engine such as Bullet and transform it to be 2D based? use the source code of a 2D Rigid body physics engine such as box2d as a starting point?

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  • How do engines avoid "Phase Lock" (multiple objects in same location) in a Physics Engine?

    - by C0M37
    Let me explain Phase Lock first: When two objects of non zero mass occupy the same space but have zero energy (no velocity). Do they bump forever with zero velocity resolution vectors or do they just stay locked together until an outside force interacts? In my home brewed engine, I realized that if I loaded a character into a tree and moved them, they would signal a collision and hop back to their original spot. I suppose I could fix this by implementing impulses in the event of a collision instead of just jumping back to the last spot I was in (my implementation kind of sucks). But while I make my engine more robust, I'm just curious on how most other physics engines handle this case. Do objects that start in the same spot with no movement speed just shoot out from each other in a random direction? Or do they sit there until something happens? Which option is generally the best approach?

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  • Approximating walking physics via simpler sliding physics

    - by Dave
    I am modeling walking insects. I implement them as cuboids and use forces (including friction and drag), to control motion. However, the movement characteristics of this 'sliding box' physics don't match those due to a legged creature. For example, legged creatures near-instantly accelerate to their top speed; whereas applying a force to a box takes time to accelerate it. The applied force can be increased along with the counteracting drag, giving much quicker acceleration (via force) to a max speed (via drag). However, this also means the force that creatures can exert when pushing on other objects is increased. Does anyone know of any techniques using a physics engine to cheaply model walking creatures?

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  • How to implement friction in a physics engine based on "Advanced Character Physics"

    - by paldepind
    I have implemented a physics engine based on the concepts in the classic text Advanced Character Physics by Thomas Jakobsen. Friction is only discussed very briefly in the article and Jakobsen himself notes how "other and better friction models than this could and should be implemented." Generally how could one implement a believable friction model on top of the concepts from the mentioned article? And how could the found friction be translated into rotation on a circle? I do not want this question to be about my specific implementation but about how to combine Jakobsens ideas with a great friction system more generally. But here is a live demo showing the current state of my engine which does not handle friction in any way: http://jsfiddle.net/Z7ECB/embedded/result/ Below is a picture showing and example on how collision detection could work in an engine based in the paper. In the Verlet integration the current and previous position is always stored. Based on these a new position is calculated. In every frame I calculate the distance between the circles and the lines. If this distance is less than a circles radius a collision has occurred and the circle is projected perpendicular out of the offending line according to the size of the overlap (offset on the picture). Velocity is implicit due to Verlet integration so changing position also changes the velocity. What I need to do know is to somehow determine the amount of friction on the circle and move it backwards parallel to the line in order to reduce its speed.

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  • Good 2D Platformer Physics

    - by Joe Wreschnig
    I have a basic character controller set up for a 2D platformer with Box2D, and I'm starting to tweak it to try to make it feel good. Physics engines have a lot of knobs to tweak, and it's not clear to me, writing with a physics engine for the first time, which ones I should use. Should jumping apply a force for several ticks? An impulse? Directly set velocity? How do I stop the avatar from sticking to walls without taking away all its friction (or do I take away all the friction, but only in the air)? Should I model the character as a capsule? A box with rounded corners? A box with two wheels? Just one big wheel? I feel like someone must have done this before! There seem to be very few resources available on the web that are not "baby's first physics", which all cut off where I'm hoping someone has already solved the issues. Most examples of physics engines for platformers have floaty-feeling controls, or in-air jumps, or easily exploitable behavior when temporary penetration is too high, etc. Some examples of what I mean: A short tap of jump jumps a short distance; a long tap jumps higher. Short skidding when stopping or reversing directions at high velocity. Standing stably on inclines (but maybe sliding down them when ducking). Analog speed when using an analog controller. All the other things that separate good platformers from bad platformers. Dare I suggest, stable moving platforms? I'm not really looking for "hey, do this." Obviously, the right thing to do is dependent on what I want in the game. But I'm hoping someone somewhere has gone through the possibilities and said "well technique A does feature X well, technique B does Y well, but that doesn't work with C", or has some worked examples beyond "if (key == space) character.impulse(0, 1)"

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  • Small-Scale Physics Engine

    - by user1276078
    I'm entering Android game development, and I already have a computer version of a game I want to publish. The thing is, I want to make this as good as it can be. With that said, I need a physics engine, really to only do one thing. That one thing is to make a parabolic movement of my main character as he's jumping in the air. Currently, my computer version simply makes the guy move up at a 45 degree angle, and as soon as it hits the ceiling, down at a 45 degree angle. I need a physics engine/library that would accomplish that, it has to be in java since that's my best language, it has to be 2D, and it has to be able to work on Android. Which physics engine/library could accomplish all of that?

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  • How should I invoke a physics engine?

    - by ymfoi
    I'm new to writing games. I'm planning to write a 2D battle game which may require an physics engine. Suppose I've written one, but how can I combine it with the main routine of my game? Should I attach it directly to the graphics render routine or put it in an individual thread? I've spent much time looking for some common approach, but found nothing. So can you reveal some basics idea for me, a newbie? Thanks! P.S. There're many other problems I have to deal with if I choose to start a separate thread for the physics engine, for example, the lock problem, while from my intuition, I guess I'd better separate the render and the physics engine.

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  • How does 2D Game Physics work? [closed]

    - by StefanE
    Possible Duplicate: How do I build a 2D physics engine? If we take the game Angry Birds that had big success lately I were thinking how do they implement the physics in a game like that? Your are shooting of your birds and they hit something that will fall off and in turn creating a chain reaction of things either falling or exploding.. Are all this happening with calculations with rules considering all collisions together with gravity etc.?

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  • How do I build a 2D physics engine?

    - by Vish
    The most advanced games I've made are a 8-ball pool game made with the physics engine Box2dFlashAS3 and a platform game with levels. When I did platform games, I've always wished to know how to make an engine, so that I could re-use it. When I see games that have slopes, curved slopes, perfect gravity and real-life physics, I've always wished I knew how to code the engine. Please suggest techniques and articles for whatever relevant knowledge-base is necessary.

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  • How to Make Objects Fall Faster in a Physics Simulation

    - by David Dimalanta
    I used the collision physics (i.e. Box2d, Physics Body Editor) and implemented onto the java code. I'm trying to make the fall speed higher according to the examples: It falls slower if light object (i.e. feather). It falls faster depending on the object (i.e. pebble, rock, car). I decided to double its falling speed for more excitement. I tried adding the mass but the speed of falling is constant instead of gaining more speed. check my code that something I put under input processor's touchUp() return method under same roof of the class that implements InputProcessor and Screen: @Override public boolean touchUp(int screenX, int screenY, int pointer, int button) { // TODO Touch Up Event if(is_Next_Fruit_Touched) { BodyEditorLoader Fruit_Loader = new BodyEditorLoader(Gdx.files.internal("Shape_Physics/Fruity Physics.json")); Fruit_BD.type = BodyType.DynamicBody; Fruit_BD.position.set(x, y); FixtureDef Fruit_FD = new FixtureDef(); // --> Allows you to make the object's physics. Fruit_FD.density = 1.0f; Fruit_FD.friction = 0.7f; Fruit_FD.restitution = 0.2f; MassData mass = new MassData(); mass.mass = 5f; Fruit_Body[n] = world.createBody(Fruit_BD); Fruit_Body[n].setActive(true); // --> Let your dragon fall. Fruit_Body[n].setMassData(mass); Fruit_Body[n].setGravityScale(1.0f); System.out.println("Eggs... " + n); Fruit_Loader.attachFixture(Fruit_Body[n], Body, Fruit_FD, Fruit_IMG.getWidth()); Fruit_Origin = Fruit_Loader.getOrigin(Body, Fruit_IMG.getWidth()).cpy(); is_Next_Fruit_Touched = false; up = y; Gdx.app.log("Initial Y-coordinate", "Y at " + up); //Once it's touched, the next fruit will set to drag. if(n < 50) { n++; }else{ System.exit(0); } } return true; } And take note, at show() method , the view size from the camera is at 720x1280: camera_1 = new OrthographicCamera(); camera_1.viewportHeight = 1280; camera_1.viewportWidth = 720; camera_1.position.set(camera_1.viewportWidth * 0.5f, camera_1.viewportHeight * 0.5f, 0f); camera_1.update(); I know it's a good idea to add weight to make the falling object falls faster once I released the finger from the touchUp() after I picked the object from the upper right of the screen but the speed remains either constant or slow. How can I solve this? Can you help?

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  • Which physics phenomenons can be simulated properly with Box2d or bullet physics? [on hold]

    - by user3585425
    Knowing that box2d or bullet physics can't simulate Newton's cradle (because of multiple bodies being in contact at the same time if I understand correctly), is there a sets of physics phenomenons that imply two or more objects that still can be simulated properly ? For example, I'm thinking about lightweight objects launched towards heavyweight objects. If the object is destroyed on contact, this would not make a difference if the energy is not transmitted correctly on impact.

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  • Game Physics With RK4 Implementation For A 2D Platformer

    - by oscar.rpr
    I been reading about RK4 for physics implementation in a game, so I read in some pages and all people recommend me this page: http://gafferongames.com/game-physics/fix-your-timestep/ This page shows clearly how this one works, but I can't figure out how to implement in my game, maybe I don't understand that good but I find some things that are not really clearly to me. In my game, the player decides when change direction in the X-Axis but I can't figure out how with this RK4 implementation change the direction of the object, in the example the point goes side to side but I don't understand how I can control when he goes right or left. So if anyone can give a little bit of clarity in this implementation and my problem which I do not understand I will be really grateful. Thanks beforehand

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  • gpgpu vs. physX for physics simulation

    - by notabene
    Hello First theoretical question. What is better (faster)? Develop your own gpgpu techniques for physics simulation (cloth, fluids, colisions...) or to use PhysX? (If i say develop i mean implement existing algorithms like navier-strokes...) I don't care about what will take more time to develop. What will be faster for end user? As i understand that physx are accelerated through PPU units in gpu, does it mean that physical simulation can run in paralel with rastarization? Are PPUs different units than unified shader units used as vertex/geometry/pixel/gpgpu shader units? And little non-theoretical question: Is physx able to do sofisticated simulation equal to lets say Autodesk's Maya fluid solver? Are there any c++ gpu accelerated physics frameworks to try? (I am interested in both physx and gpgpu, commercial engines are ok too).

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  • Physics System ignores collision in some rare cases

    - by Gajoo
    I've been developing a simple physics engine for my game. since the game physics is very simple I've decided to increase accuracy a little bit. Instead of formal integration methods like fourier or RK4, I'm directly computing the results after delta time "dt". based on the very first laws of physics : dx = 0.5 * a * dt^2 + v0 * dt dv = a * dt where a is acceleration and v0 is object's previous velocity. Also to handle collisions I've used a method which is somehow different from those I've seen so far. I'm detecting all the collision in the given time frame, stepping the world forward to the nearest collision, resolving it and again check for possible collisions. As I said the world consist of very simple objects, so I'm not loosing any performance due to multiple collision checking. First I'm checking if the ball collides with any walls around it (which is working perfectly) and then I'm checking if it collides with the edges of the walls (yellow points in the picture). the algorithm seems to work without any problem except some rare cases, in which the collision with points are ignored. I've tested everything and all the variables seem to be what they should but after leaving the system work for a minute or two the system the ball passes through one of those points. Here is collision portion of my code, hopefully one of you guys can give me a hint where to look for a potential bug! void PhysicalWorld::checkForPointCollision(Vec2 acceleration, PhysicsComponent& ball, Vec2& collisionNormal, float& collisionTime, Vec2 target) { // this function checks if there will be any collision between a circle and a point // ball contains informations about the circle (it's current velocity, position and radius) // collisionNormal is an output variable // collisionTime is also an output varialbe // target is the point I want to check for collisions Vec2 V = ball.mVelocity; Vec2 A = acceleration; Vec2 P = ball.mPosition - target; float wallWidth = mMap->getWallWidth() / (mMap->getWallWidth() + mMap->getHallWidth()) / 2; float r = ball.mRadius / (mMap->getWallWidth() + mMap->getHallWidth()); // r is ball radius scaled to match actual rendered object. if (A.any()) // todo : I need to first correctly solve the collisions in case there is no acceleration return; if (V.any()) // if object is not moving there will be no collisions! { float D = P.x * V.y - P.y * V.x; float Delta = r*r*V.length2() - D*D; if(Delta < eps) return; Delta = sqrt(Delta); float sgnvy = V.y > 0 ? 1: (V.y < 0?-1:0); Vec2 c1(( D*V.y+sgnvy*V.x*Delta) / V.length2(), (-D*V.x+fabs(V.y)*Delta) / V.length2()); Vec2 c2(( D*V.y-sgnvy*V.x*Delta) / V.length2(), (-D*V.x-fabs(V.y)*Delta) / V.length2()); float t1 = (c1.x - P.x) / V.x; float t2 = (c2.x - P.x) / V.x; if(t1 > eps && t1 <= collisionTime) { collisionTime = t1; collisionNormal = c1; } if(t2 > eps && t2 <= collisionTime) { collisionTime = t2; collisionNormal = c2; } } } // this function should step the world forward by dt. it doesn't check for collision of any two balls (components) // it just checks if there is a collision between the current component and 4 points forming a rectangle around it. void PhysicalWorld::step(float dt) { for (unsigned i=0;i<mObjects.size();i++) { PhysicsComponent &current = *mObjects[i]; Vec2 acceleration = current.mForces * current.mInvMass; float rt=dt; // stores how much more the world should advance while(rt > eps) { float collisionTime = rt; Vec2 collisionNormal = Vec2(0,0); float halfWallWidth = mMap->getWallWidth() / (mMap->getWallWidth() + mMap->getHallWidth()) / 2; // we check if there is any collision with any of those 4 points around the ball // if there is a collision both collisionNormal and collisionTime variables will change // after these functions collisionTime will be exactly the value of nearest collision (if any) // and if there was, collisionNormal will report in which direction the ball should return. checkForPointCollision(acceleration,current,collisionNormal,collisionTime,Vec2(floor(current.mPosition.x) + halfWallWidth,floor(current.mPosition.y) + halfWallWidth)); checkForPointCollision(acceleration,current,collisionNormal,collisionTime,Vec2(floor(current.mPosition.x) + halfWallWidth, ceil(current.mPosition.y) - halfWallWidth)); checkForPointCollision(acceleration,current,collisionNormal,collisionTime,Vec2( ceil(current.mPosition.x) - halfWallWidth,floor(current.mPosition.y) + halfWallWidth)); checkForPointCollision(acceleration,current,collisionNormal,collisionTime,Vec2( ceil(current.mPosition.x) - halfWallWidth, ceil(current.mPosition.y) - halfWallWidth)); // either if there is a collision or if there is not we step the forward since we are sure there will be no collision before collisionTime current.mPosition += collisionTime * (collisionTime * acceleration * 0.5 + current.mVelocity); current.mVelocity += collisionTime * acceleration; // if the ball collided with anything collisionNormal should be at least none zero in one of it's axis if (collisionNormal.any()) { collisionNormal *= Dot(collisionNormal, current.mVelocity) / collisionNormal.length2(); current.mVelocity -= 2 * collisionNormal; // simply reverse velocity along collision normal direction } rt -= collisionTime; } // reset all forces for current object so it'll be ready for later game event current.mForces.zero(); } }

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  • Game physics / 2D Collision detection AS3

    - by Jery
    I know there are some methods you can use like hittestPoint and so on, but I want to see where my movieclip colliedes with another another movieclip. Any other methods I can use? by any chance does somebody know some a good introduction to game physics? Im asking because I coded a small engine and pretty much the whole code is spagetti code thats why I would like to know how you can setup something like this properly

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  • Resolution independent physics

    - by user46877
    I'm making a game like Doodlejump but don't know how to make the physics scale on multiple resolutions. I also can't find anything related to this on Google. Right now I'm scaling the game using letterboxing and tested scaling the jump height with this code: gravity = graphics.getHeight() * 0.001f; jumpVel = graphics.getHeight() * -0.04f; ... velY += gravity; y += velY; But if I test this on my smartphone or emulator with different resolutions, I always get a slightly different jump height. I know that Farseer is resolution independent. How can I replicate this in my game? Thanks in advance.

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  • Game Physics: Implementing Normal Reaction from ground correctly

    - by viraj
    I am implementing a simple side scrolling platform game. I am using the following strategy while coding the physics: Gravity constantly acts on the character. When the character is touching the floor, a normal reaction is exerted by the floor. I face the following problem: If the character is initially at a height, he acquires velocity in the -Y direction. Thus, when he hits the floor, he falls through even though normal force is being exerted. I could fix this by setting the Y velocity to 0, and placing him above the floor if he has collided with it. But this often leads to the character getting stuck in the floor or bouncing around it. Is there a better approach ?

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