I have been trying to use a MouseJoint to move a piece wherever the user touches. But the piece, being affected by the joint, behaves strangely, never reaching the point. This is the code (x and y are already converted to 'physical' units):
MouseJointDef mj_def;
MouseJoint mj = null;
Body mj_gbody;
public void move(float x, float y)
{
if(mj == null)
{
BodyDef mgbd = new BodyDef();
mj_gbody = wrld.createBody(mgbd);
//
mj_def = new MouseJointDef();
mj_def.bodyA = mj_gbody;
mj_def.bodyB = body;
mj_def.collideConnected = true;
mj_def.maxForce = 20.0f * body.getMass();
//mj_def.target.set(x,y);
mj = (MouseJoint)wrld.createJoint(mj_def);
body.setAwake(true);
}
mj.setTarget(new Vector2(x, y));
}
I was looking for some way to establish the anchor point in the BodyB, as the 'strange behaviour' that I mentioned seems to make the body gravitate around the established point (an orbit twice the width of the object), as if the anchor point was outside of the body (hexagon shaped, btw). But I don't see any way of doing so in libgdx.
Does anybody know what I am doing wrong? Thank you in advance!
Well, MouseJoint was working properly, I just misunderstood how MouseJoint works.
As it is clearly seen in the Box2d testbed, MouseJoint is used for dragging after selecting an object. Therefore, the anchor is assigned in the first target.set.
As I wanted to move the center of the object to the place where the mouse was (or the user touched), a mj_def.target.set(body.getPosition().x + 2.0f, body.getPosition().y + 1.0f); (the object is 4.0f by 2.0f) in the initialization solved the problem. Also, it may be not the best Joint for my intentions (to move an specific object to one place in the screen).
Related
There are few actors on stage, lines are drawn connecting centers of them, like a graph, Nodes and edges. Nodes are gradable. On Drag I am using the following code
public void touchDragged(InputEvent event, float eventOffsetX, float
eventOffsetY, int pointer)
{
float deltaX = eventOffsetX - self.grabOffsetX;
float deltaY = eventOffsetY - self.grabOffsetY;
self.moveBy(deltaX, deltaY);
moveCoordinatesBy((int)deltaX,(int)deltaY);
}
the Method moveCoordinatesBy is updating the coordinate of the center of the node. which is used to draw lines (Edges) connecting the. This is working Fine.
My problem is - When I am using moveTo action for Nodes, I need to update edges at the same time. For this I need to update coordinates of there center. To do this I am using the following code in the act method of the Node -
public void act(float dt)
{
super.act(dt);
Vector2 loc = new Vector2();
loc.x = self.getX()+ self.getWidth()/2;
loc.y = self.getY() + self.getHeight()/2;
Vector2 v = new Vector2();
v = self.localToStageCoordinates(loc);
setCoordinates((int)v.x, (int)v.y);
}
The coordinates I am getting are not center of the node, they are almost multiplied by 2. Am I doing something wrong?
And also getWidth() and self.getHeight() returning double the size. When actor (node) is scaled getWidth() and self.getHeight() are returning arbitery values depending on how for it is located on stage. Further from (0,0) larger the returned value.
v = self.localToStageCoordinates(loc);
above line of code not needed, beacuse all the actors were directly added to the stage. By removing localToStageCoordinates(loc) its working fine now.
I'm creating a Android game with Unity and I'm trying to make an object to follow my finger. This is the code I'm using.
for (int i = 0; i < Input.touchCount; i++)
{
RaycastHit2D hit = Physics2D.Raycast(Camera.main.ScreenToWorldPoint(Input.touches[i].position), Vector2.zero);
Vector3 touchPosition = Camera.main.ScreenToWorldPoint(Input.touches[i].position);
if (Input.GetTouch(i).phase == TouchPhase.Moved && hit.collider != null)
{
transform.position = new Vector2(touchPosition.x, touchPosition.y + sizeY);
}
}
I put the collider bellow the object and I added the size of the object to the Y, so it appears above my finger.
The problem is that if I move my finger slightly faster, I lose the object, that stays behind. Since the object lags behind, if I move my finger faster I end up out of the collider area and the object just stop moving.
The only way I found that works is to get rid of the Raycast thing and make the object follow the touch anywhere in the screen (I don't like that).
I just want to know if this is the best I can get from Unity and Android or if there a is way to make an object follow the finger in a one-by-one movement, with precision, without lag.
I'm testing on a Samsung Galaxy S8 just with the object and nothing else.
You are not alone with this issue. Unity's Input API is frame-rate based and may not keep with the speed of the touch movement on the screen. If you're working on something that requires fast response based on the touch on the screen, use the new Unity's InputSystem. This API is still in experimental mode.
Its Touchscreen class can be used to access the touch on the screen. Your current code should translate into something like below:
public int touchIndex = 0;
void Update()
{
Touchscreen touchscreen = UnityEngine.Experimental.Input.Touchscreen.current;
if (touchscreen.allTouchControls[touchIndex].ReadValue().phase != PointerPhase.None &&
touchscreen.allTouchControls[touchIndex].ReadValue().phase == PointerPhase.Moved)
{
Vector2 touchLocation = touchscreen.allTouchControls[touchIndex].ReadValue().position;
RaycastHit2D hit = Physics2D.Raycast(Camera.main.ScreenToWorldPoint(touchLocation), Vector2.zero);
Vector3 touchPosition = Camera.main.ScreenToWorldPoint(touchLocation);
transform.position = new Vector2(touchPosition.x, touchPosition.y + sizeY);
}
}
I'm making a simple jumping game for android using libgdx and box2d and I cannot figure out how to make sprites move really smooth. I have checked several articles regarding timestep fixing and synchronizing renderer and physics emulation, but none of the suggested ways really helped (http://gafferongames.com/game-physics/fix-your-timestep/).
Finally I decided to run the most simple test setting box2d world step equal to the framerate (which in case of stable fps should provide the best performance), but still movement is not totally smooth. I have tested on PC and on Android device, with stable 60-61 FPS. Here is pseudocode:
In render:
world.step(Gdx.graphics.getDeltaTime(), 6, 2);
stage.act();
stage.draw();
Stage basically has just one actor with act and draw overriden:
#Override
public void draw(Batch batch, float arg1) {
float x = this.getX() - width/2;
float y = this.getY() - height/2;
batch.draw(sprite, x, y, width, height);
}
#Override
public void act (float delta) {
...
//get body position
position = body.getPosition();
this.setPosition(position.x, position.y);
}
Actor has box2d body attached to it, there is no gravity and body's velocity is set constant:
BodyDef bodyDef = new BodyDef();
bodyDef.type = BodyType.DynamicBody;
bodyDef.position.set(world_position);
bodyDef.linearDamping = 0f;
bodyDef.angularDamping = 0f;
bodyDef.fixedRotation = true;
bodyDef.gravityScale = 0f;
...fixure added to the body
body.setLinearVelocity(0, -2f);
Camera is not moving, the case seems to be dead simple and yet sprite does not move exactly perfect. (Though it still looks smoother then when using time accumulator and interpolation)
Is it possible to achive absolutely smooth movement at all? Is there some mistake in my approach?
I have checked some similar games on the same android device - it seems that objects are moving absolutely smooth, but maybe it just seems so, because too many things happen on the screen and I don't have time to notice.
Any advice would be appreciated.
After further testing and researched I have figured out the problem - it was related not to FPS, but to pixel rounding. Box2d bodies have float coordinates - after converting them to round pixel values animation bemace much smoother.
How about to use CCPhysicsSprite instead of change position of sprite by time? You can use a batch, too. Just
sprite = [CCPhysicsSprite spriteWithTexture:batch.texture];
[batch addChild:sprite];
CCPhysicsSprite class
Example:
#import "CCPhysicsSprite.h"
CCPhysicsSprite *sprite = [CCPhysicsSprite spriteWithFile:#"sprite.png"];
[self addChild:sprite];
b2BodyDef bodyDef;
bodyDef.type = b2_dynamicBody;
bodyDef.position.Set(300/PTM_RATIO, 200/PTM_RATIO);
body = world->CreateBody(&bodyDef);
b2CircleShape circleShape;
circleShape.m_radius = 0.3;
b2FixtureDef fixtureDef;
fixtureDef.shape = &circleShape;
fixtureDef.density = 1;
fixtureDef.friction = 0.3f;
body->CreateFixture(&fixtureDef);
[sprite setPTMRatio:PTM_RATIO];
[sprite setB2Body:body];
[sprite setPosition: ccp(300, 200)];
I managed to load a tmx map now I would like to create the obstacle that the sprite can not move, I recovered the obstacle like this :
try {
final TMXLoader tmxLoader = new TMXLoader(this, this.mEngine.getTextureManager(), TextureOptions.BILINEAR_PREMULTIPLYALPHA, new ITMXTilePropertiesListener() {
#Override
public void onTMXTileWithPropertiesCreated(final TMXTiledMap pTMXTiledMap, final TMXLayer pTMXLayer, final TMXTile pTMXTile, final TMXProperties<TMXTileProperty> pTMXTileProperties) {
/* We are going to count the tiles that have the property "cactus=true" set. */
if(pTMXTileProperties.containsTMXProperty("obstacle", "true")) {
//TMXTiledMapExample.this.mCactusCount++;
//coffins[coffinPtr++] = pTMXTile.getTileRow() * 15 + pTMXTile.getTileColumn();
}
}
});
How do I handle collisions with obstacles so as to prevent the player from walking through the obstacle (i.e., like a wall)?
I believe what you're asking is how do you implement collision handling. To be clear: Collision detection is the step where you determine that something is colliding(overlapping) with something else. Collision handling is where you, say, move one of those things such that it is no longer overlapping. In this case, I'm assuming we're past the collision detection and on to collision handling because you're in a method called "onTMXTileWithPropertiesCreated," which I'm guessing means the player is on such a tile. So here's the idea, put very simply:
When, due to the movement of the player (or some other sprite) you detect that the sprite is colliding with a sprite that you would like to be impassable -- "real" in your terms, you're going to want to move the sprite back the distance that would prevent it from overlapping.
Doing this with rectangles is very simple. Doing it with other shapes gets a little more complicated. Because you're working with a TMX tile map, rectangles will probably work for now. Here's a basic example with rectangles.
public boolean adjustForObstacle(Rect obstacle) {
if (!obstacle.intersect(this.getCollisionRect())) return false;
// There's an intersection. We need to adjust now.
// Due to the way intersect() works, obstacle now represents the
// intersection rectangle.
if (obstacle.width() < obstacle.height()) {
// The intersection is smaller left/right so we'll push accordingly.
if (this.getCollisionRect().left < obstacle.left) {
// push left until clear.
this.setX(this.getX() - obstacle.width());
} else {
// push right until clear.
this.setX(this.getX() + obstacle.width());
}
} else {
if (this.getCollisionRect().top < obstacle.top) {
// push up until clear.
this.setY(this.getY() - obstacle.height());
} else {
// push down until clear.
this.setY(this.getY() + obstacle.height());
}
}
return true;
}
What this is doing is calculating the overlapping rectangle and moving the sprite along the smallest dimension of overlap by the amount that will make it no longer overlap. Since you're using AndEngine, you can make use of the collidesWith() method in IShape, which detects collisions more elegantly than the above approach.
since I use this
if(pTMXTileProperties.containsTMXProperty("obstacle", "true")) {
//TMXTiledMapExample.this.mCactusCount++;
//coffins[coffinPtr++] = pTMXTile.getTileRow() * 15 + pTMXTile.getTileColumn();
//initRacetrackBorders2();
// This is our "wall" layer. Create the boxes from it
final Rectangle rect = new Rectangle(pTMXTile.getTileX()+10, pTMXTile.getTileY(),14, 14);
final FixtureDef boxFixtureDef = PhysicsFactory.createFixtureDef(0, 0, 1f);
PhysicsFactory.createBoxBody(mPhysicsWorld, rect, BodyType.StaticBody, boxFixtureDef);
rect.setVisible(false);
mScene.attachChild(rect);
}
Have fun !
I am trying to pick objects in the bullet physics world but all I seem to be able to pick is the floor/ground plane!!! I am using the Vuforia SDK and have altered the ImageTargets demo code. I have used the following code to project my touched screen points to the 3d world:
void projectTouchPointsForBullet(QCAR::Vec2F point, QCAR::Vec3F &lineStart, QCAR::Vec3F &lineEnd, QCAR::Matrix44F &modelViewMatrix)
{
QCAR::Vec4F normalisedVector((2 * point.data[0] / screenWidth - 1),
(2 * (screenHeight-point.data[1]) / screenHeight - 1),
-1,
1);
QCAR::Matrix44F modelViewProjection;
SampleUtils::multiplyMatrix(&projectionMatrix.data[0], &modelViewMatrix.data[0] , &modelViewProjection.data[0]);
QCAR::Matrix44F inversedMatrix = SampleMath::Matrix44FInverse(modelViewProjection);
QCAR::Vec4F near_point = SampleMath::Vec4FTransform( normalisedVector,inversedMatrix);
near_point.data[3] = 1.0/near_point.data[3];
near_point = QCAR::Vec4F(near_point.data[0]*near_point.data[3], near_point.data[1]*near_point.data[3], near_point.data[2]*near_point.data[3], 1);
normalisedVector.data[2] = 1.0;//z coordinate now 1
QCAR::Vec4F far_point = SampleMath::Vec4FTransform( normalisedVector, inversedMatrix);
far_point.data[3] = 1.0/far_point.data[3];
far_point = QCAR::Vec4F(far_point.data[0]*far_point.data[3], far_point.data[1]*far_point.data[3], far_point.data[2]*far_point.data[3], 1);
lineStart = QCAR::Vec3F(near_point.data[0],near_point.data[1],near_point.data[2]);
lineEnd = QCAR::Vec3F(far_point.data[0],far_point.data[1],far_point.data[2]);
}
when I try a ray test in my physics world I only seem to be hitting the ground plane! Here is the code for the ray test call:
QCAR::Vec3F intersection, lineStart;
projectTouchPointsForBullet(QCAR::Vec2F(touch1.tapX, touch1.tapY), lineStart, lineEnd,inverseProjMatrix, modelViewMatrix);
btVector3 btRayFrom = btVector3(lineEnd.data[0], lineEnd.data[1], lineEnd.data[2]);
btVector3 btRayTo = btVector3(lineStart.data[0], lineStart.data[1], lineStart.data[2]);
btCollisionWorld::ClosestRayResultCallback rayCallback(btRayFrom,btRayTo);
dynamicsWorld->rayTest(btRayFrom, btRayTo, rayCallback);
if(rayCallback.hasHit())
{
char* pPhysicsData = reinterpret_cast<char*>(rayCallback.m_collisionObject->getUserPointer());//my bodies have char* messages attached to them to determine what has been touched
btRigidBody* pBody = btRigidBody::upcast(rayCallback.m_collisionObject);
if (pBody && pPhysicsData)
{
LOG("handleTouches:: notifyOnTouchEvent from physics world!!!");
notifyOnTouchEvent(env, obj,0,0, pPhysicsData);
}
}
I know I am predominantly looking top-down so I am bound to hit the ground plane, I at least know my touch is being correctly projected into the world, but I have objects lying on the ground plane and I can't seem to be able to touch them! Any pointers would be greatly appreciated :)
I found out why I wasn't able to touch the objects - I am scaling the objects up when they are drawn, so I had to scale the view matrix by the same value before I projected my touch point into the 3d world (EDIT I also had the btRayFrom and btRayTo input cooordinates reversed, it is now fixed):
//top of code
int kObjectScale = 100.0f
....
...
//inside touch handler method
SampleUtils::scalePoseMatrix(kObjectScale, kObjectScale, kObjectScale,&modelViewMatrix.data[0]);
projectTouchPointsForBullet(QCAR::Vec2F(touch1.tapX, touch1.tapY), lineStart, lineEnd,inverseProjMatrix, modelViewMatrix);
btVector3 btRayFrom = btVector3(lineStart.data[0], lineStart.data[1], lineStart.data[2]);
btVector3 btRayTo = btVector3(lineEnd.data[0], lineEnd.data[1], lineEnd.data[2]);
My touches are projected correctly now :)