I am trying to achieve a simple throw effect in as3:
I put my finger on the screen and then swipe it as if I throw an object.
The goal is to simulate a ball movement according to the swipe (direction, speed)
What gesture should I use?
I tried TransformGestureEvent.GESTURE_SWIPE
But this just give me the direction (left right, top, bottom) and no velocity or force or speed.
regards
There are many libraries and frameworks that handles touch input and can process complex gestures, you can google for them and find many easily.
You can also write your own, simple input processor that will give you the desired info.
On touch begin set values to 3 variables:
start x
start y
timestamp
Get the starting position be either the screen global position (you can access it from the TouchEvent object on your handler) or on the InteractiveObject (e.g. Sprite) mouseX and mouseY - that will give you relative position.
Timestamp can be easily taken with getTimer(), also the fastest way to get timestamp in Flash.
On touch end get other 3 variables
end x
end y
end timestamp
Knowing the difference of x and y positions and the time spent to make a gesture you'll be able to find the desired data - angle (using trigonometry or Math.atan2()), velocity, speed, force (by distance between x,y or time delta or both)
Hope that answers your question!
Related
I would like to get the touch screen drawing position (x and y) and direction (moving up or down or left or ....), then I will compare it with some stored positions and directions for characters (as we are trying to teach character writing). Isn't there any known library or helping things for this?
Thanks in advance
Every DisplayObject has the properties mouseX and mouseY, that indicate the mouse position with respect to its origin.
To get the direction, save the values of both properties and compare them to the next ones. Say for example within the handler of a MouseEvent.MOUSE_MOVE Event.
I have a main object that moves around wherever the mouse is.
How would I make an animation that shoots out other objects from the main object toward receivers that don't move?
Is there an easier way than finding the angle between the main object and the receivers and then sending the animation out that way?
So the shooting animation should rotate depending on where the main object is so that the shooting animations will always reach the target.
You can use TweenLite and just specify the x, y location :
TweenLite.to(bullet, duration, {x:targetX, y:targetY});
You can download it here :
http://www.greensock.com/v12/
You'll probably want to calculate the duration of the tween based on the distance between the objects and how fast you'd like it to move in pixels per second. For example :
var duration:Number = distance / pixelsPerSecond;
That would give you the correct amount of time for the tween.
I've tried unsuccessfully (because of my poor 3D geometry understanding and unfortunate lack of time to dig in) to build a GoogleEarth-like controls for three.js. Maybe someone can help me, or might already have it. Anyways, i think it would be an excellent addition to three.js library.
Here's the specific functionality I am trying to build:
Zoom in with mouse wheel TO MOUSE CURSOR
Rotate around the scene by holding down Shift
Pan by pressing left mouse button.
As a bonus: show a little target icon during 1 and 2 operations above.
I have most trouble with 1, and haven't attempted 2. Panning is easy (there are lots of examples).
Right now I am unable to zoom into the scene so that it stays fixed under the cursor (so I can point at the top right corner of the screen, zoom-in and still see what I had under the cursor).
My thanks in advance,
Alex
I've implemented something similar in a past life. I assume here that you are interacting with a flat plane; conversion of these techniques to a plane tangent to a sphere is left as an exercise for the reader. ;)
Zoom in with mouse wheel TO MOUSE CURSOR
To do this, you'll want to cast a ray into the scene, and note where it hits. You'll then want to translate the eye point of the camera towards that intersection. To feel "correct", you'll want some kind of proportional zoom in instead of fixed steps--for example, each zoom step reduces the distance from the current eye point to the target by 20%, instead of just moving 20 units. This will automatically slow down the camera as it approaches.
Rotate around the scene by holding down Shift
One you hold shift, you'll want left and right mouse movements to orbit about your view point. To do this, you'll need to yaw about an axis perpendicular to your point of intersection. You'll cast a ray into the scene (once shift is held down), note the intersection point, and then rotate your camera's eye point about that axis. Note that you'll need also to reorient the camera to continually point towards that intersection as you rotate, or perhaps to have the eye direction rotate to keep a constant angle with the vector from the eye point to the intersection axis.
Pan by pressing left mouse button.
You simply need to get the eye right vector and eye up vector, and move in the appropriate direction (multiply the mouse dx/dy with the normalized eye right/eye up, and multiply by the timestep for framerate independent movement).
As a bonus: show a little target icon during 1 and 2 operations above.
At the intersection in the scene, add a little object. Once you exit a mode, remove the object.
for your first question you can use this program under mouse wheel
mousewheel = function (event) {
event.preventDefault();
var factor = 15;
var mX = (event.clientX / jQuery(THREE_STUFF.container).width()) * 2 - 1;
var mY = -(event.clientY / jQuery(THREE_STUFF.container).height()) * 2 + 1;
var vector = new THREE.Vector3(mX, mY, 0.1);
vector.unproject(camera);
vector.sub(camera.position);
if (event.deltaY < 0) {
camera.position.addVectors(camera.position, vector.setLength(factor)); trackBallControls.target.addVectors(trackBallControls.target, vector.setLength(factor));
} else {
camera.position.subVectors(camera.position, vector.setLength(factor)); trackBallControls.target.subVectors(trackBallControls.target, vector.setLength(factor));
}
}
I hope this will help you sure.
I have created a collision class to detect collisions using pixels. In my class I've also developed some functions for determining the collsion angle. Based on this I created some examples:
http://megaswf.com/serve/25437/
http://megaswf.com/serve/25436/
(Space to change gravity, right/left to give some speed to the ball.)
As you will probably notice, there are strange things that happen:
When the ball speed is very low
When the direction of the ball is
almost tangent to the obstacle.
collision http://img514.imageshack.us/img514/4059/colisao.png
The above image shows how I calculate the collision angle.
I call the red dots the keypoints. I search for a maximum number of keypoints (normally 4). If I find more then 2 keypoints, I choose the 2 farthest ones (as shown in one of the blue objects). Thats how I then find the normal angle to where in the surface the object collided. I don't know if this is an obsolete way of doing things.
based on that angle, I rotate the speed vector to do the bouncing.
The piece of code to do the maths is here:
static public function newSpeedVector(speedX: Number, speedY: Number, normalAngle: Number): Object{
var vector_angle: Number = Math.atan2(speedY, speedX) * (180/Math.PI);
var rotating_angle: Number = (2*(normalAngle - vector_angle) + 180) % 360;
var cos_ang: Number = Math.cos(rotating_angle/DEGREES_OF_1RAD);
var sin_ang: Number = Math.sin(rotating_angle/DEGREES_OF_1RAD);
var final_speedX: Number = speedX * cos_ang - speedY * sin_ang;
var final_speedY: Number = speedX * sin_ang + speedY * cos_ang;
return {x_speed: final_speedX, y_speed: final_speedY};
}
This is how the new speed vector is calculated...
My question is, has anyone faced this kind of problem or has some idea on how to avoid this from happening?
Without seeing your code, this is the best I can provide.
Collision physics should have some velocity threshold that is considered "stopped". That is, once the velocity gets small enough you should explicitly mark an object as stopped and exempt it from your collision code. This will help stabilize slow moving objects. Trial and error is required for a good threshold.
When a collision happens, it is important to at least attempt to correct any inter-penetration. This is most likely the reason why tangent collisions are behaving strangely. Attempt to move the colliding object away from what it hit in a reasonable manner.
Your method of determining the normal should work fine. Game physics is all about cheating (cheating in a way that still looks good). I take it rotation and friction isn't a part of what you're going for?
Try this. You have the contact normal. When you detect a collision, calculate the penetration depth and move your object along the normal so that is isn't penetrating anymore. You can use the two points you have already calculated to get one point of penetration, you'll need to calculate the other though. For circles it's easy (center point + radius in direction of normal). There are more complex ways of going about this but see if the simple method works well for you.
I have read and recommend this book: Game Physics Engine Development
I did something a little like that and got a similar problem.
What I did is that when the pixels from the bouncing object (a ball in your case) overlap with the pixels from the obstacle, you need to move the ball out of the obstacle so that they are not overlapping.
Say the ball is rolling on the obstacle, before your render the ball again you need to move it back by the amount of 'overlap'. If you know at what angle the ball hit the obstable just move it out along that angle.
You also need to add some damping otherwise the ball will never stop. Take a (very) small value, if the ball velocity is bellow that value, set the velocity to 0.
You can try one more thing, which I think is very effective.
You can make functions such as getNextX() and getNextY()(Which of course give their position coordinated after the next update) in your game objects and Check collision on objects based on their next position instead of their current position.
This way, the objects will never overlap, you'll know when they are about collide and apply your after collision physics gracefully!
To clarify things, what i am trying to do is to get the openGL coordinates and manipulate them in my mfc code. not to get an openGL object. i'm using the mfc to control the position of the objects in the openGL.
Hi, i'm trying to find the naswer on the web and can't find a full solution that i can use and that will work...
I'm developing a MFC project with static picture as the canvas for an openGL class that draw the grphics for my game.
On moush down, i need to retrive a shape coordinate from the openGL class.
I'm looking for a way to convert the openGL coordinates to MFC coordinates but no matter what i try i get junk after using the gluProject or gluUnProject (i've tried to do both ways but non is working)
GLdouble modelMatrix[16];
glGetDoublev(GL_MODELVIEW_MATRIX,modelMatrix);
GLdouble projMatrix[16];
glGetDoublev(GL_PROJECTION_MATRIX,projMatrix);
int viewport[4];
glGetIntegerv(GL_VIEWPORT,viewport);
POINT mouse; // Stores The X And Y Coords For The Current Mouse Position
GetCursorPos(&mouse); // Gets The Current Cursor Coordinates (Mouse Coordinates)
ScreenToClient(hWnd, &mouse);
GLdouble winX, winY, winZ; // Holds Our X, Y and Z Coordinates
winX; = (float)point.x; // Holds The Mouse X Coordinate
winY; = (float)point.y; // Holds The Mouse Y Coordinate
winY = (float)viewport[3] - winY;
glReadPixels(winX, winY, 1, 1, GL_DEPTH_COMPONENT, GL_FLOAT, &winZ);
GLdouble posX=s1->getPosX(), posY=s1->getPosY(), posZ=s1->getPosZ(); // Hold The Final Values
gluUnProject( winX, winY, winZ, modelMatrix, projMatrix, viewport, &posX, &posY, &posZ);
gluProject(posX, posY, posZ, modelMatrix, projMatrix, viewport, &winX, &winY, &winZ);
This is just part of the code i've tried. ofcourse not gluProject and gluUnProject together. just had them both here to show.....and i know there is lots of junk over there, its from some of my tries...
p.s. i've tried many many more combinations and examples from the web and nothing seem to work in my case....
Can any one show me what is the right way to do the transformation?
10x
It looks like you're trying to retrieve the object (or objects) that is/are at a particular point. If this is the case, gluProject and/or gluUnProject isn't really a very suitable tool for the task. OpenGL has a selection mode intended specifically for this kind of task.
In typical use, you specify a small square (e.g., 5x5 pixels) around the mouse click spot with gluPickMatrix, set selection mode with glRenderMode, set a buffer with glSwelectBuffer, and then draw your scene. The drawing doesn't go to the screen, but fills the buffer you specified wiyh records of what was drawn within the specified area.