I've been looking for awhile now for someone who had created a good example of making good physics in JavaFX, or even just a 'basic jumping mechanic' as the title says. I can't really find any information on it and I'm not really sure how to implement the idea.
All I want is a basic example, or just an explanation, or even just a point in the direction of what element of JFX I'm going to use.
Any help is appreciated.
Thanks
I'm assuming you already have some sort of game loop that ticks 60 times a second such as the AnimationTimer. If you want the jump height to be something like 200 pixels, you need to set and objects y-velocity (velocity is added to the objects location every tick) to a large negative number (as the object is moving upwards) and add a smaller amount every tick to this velocity until it hits zero, (this will be the top of the jump) and then keep adding this value to the y-velocity until it reaches the ground or collides with something. (This value will be your gravity constant)
In essence, you need to set the y-velocity to a high value then take away small increments every tick to slow the jump until the y-velocity hits 0, then begin adding the gravity constant again until the object hits the ground, hope this helps :)
Related
I have a sphere with bounciness set to 1
The ball has no drag and uses gravity
It hits a platform, which has bounciness set to 1 and no friction
Yet, the ball bounces higher on every bounce, going to infinity. How is such a thing possible, when I have not given it any extra momentum?
The issue comes from the fact that physics in games happens in discrete frames, and that a moving object will be "inside" another at the frame where there is a collision. The physics engine then has to separate the objects before the next frame, and figure out how much energy to "bounce" with.
One of the steps to do this involves figuring out how much the objects overlap, and that's where this phantom extra energy is comin from. Less error in the overlap equals less error in the energy.
Don't fiddle with the bounciness; those are naive solutions, not to mention they sidestep the issue rather than solving it.
What you should do is to fix what's wrong with your collisions. That can be done a number of ways, the most appropriate/performant of which depends on each specific game:
Increase your physics frame rate (decrease fixed delta time). This reduces overlaps and makes physics frames "smoother". It doesn't really solve phantom energy though; only makes it's causes and effects smaller (maybe so small they become unnoticeable, which is all you need).
Set your sphere's collision detection method to Continuous Dynamic,
and set your ground to static. If you need the sphere to collide with
other stuff, those other stuff present similar issues, and those need
to be non-static, set their rigidbodies' collision detection method
to Continuous. (This is the method I most often find to be the best, but I've had projects where others were better for various reasons)
Increase your Default Solver Velocity Iterations
Change your solver type to Temporal Gauss Seidel
I have had a similar issue with javascript/html/css canvas animations. I have no explanation for this. Use a number like 0.99999 or 0.969399 and that should do the trick. I do get what you mean though it's weird. Just get close to 1. That's all I can say. I hope this helps anyway.
I don't know if this is the correct therm, but I want to get rid of any kind of forces that could modify the speed of my object. Let me explain : the game is 2D top-down view and the character fires a bullet that bounces x amount of time, WITH CONSTANT SPEED. Everything works fine, but when the bullet bounces fast and many times, its speed increases.
Also, second problem: I have a rotating object and when the bullet hits it, its speed increases (which makes sense, but I would like to know if there is a way to delete this effect) .
I would like to know if there is a way to solve my issues.
You need to check the material of the object for your first question (https://docs.unity3d.com/Manual/class-PhysicMaterial.html) you need to set Bounciness to 1 so it will maintain dame speed. If you set it to 0 there will be no bounce and probably you have a value bigger than 1 and so it's increasing.
In the second case it's all about the forces involving. The object bouncing on the rotating one is adding a force to that one. If you want to keep the second one with same rotation you could rotate it with a transform.Rotate and remove a Rigidbody or set it to static
I have been using Unity for a while and still Im not sure about some things, I know there are like 5 different ways to move our character (not using prefabs like for 1st or 3rd person controller I mean just code from scratch) so far for moving a character on a terrain I think setting the speed of the rigidbody works overal for me, just setting the x and leaving the y component as what it was before assigning that, so that gravity effect is kept, overal it works, I manage to collide with wall and other objects, manage to go on terrain and could add jump later in same fashion, but the trouble I find is that my character flies when it steps over any small object like a stone on ground, if he goes over it he starts flying, not a big distance but definetly looks like walking on the moon maybe, also I see that if I have a bridge that is lower in the middle part of it (like U shape) well the character goes like flying from the begining almost until the middle or so, as said works like being on the moon, however gravity seems ok on other objects, I know I can change the gravity value to be higher but Im affraid I could be breaking all that so my question is, is there a better way to move a character on ground that will work better without changing the gravity value? I guess that it can work right without affecting this value, I used other method to change velocity and adding a certain value to the y component but again I see it not right as an apparent correct value for small stones and small objects makes it hard to go over slopes too, any help is greatly welcome =).
I got a field in unity3d that has some depressions in it (like small holes). The field's slope always leads towards the nearest depression.
A sphere is dropped at random somewhere in the field, rolls around a bit until it stops in one of the depressions.
The problem is, this is taking too long. It could roll around for 5-10 seconds until it stops. I'd like to stop faster.
Any ideas how I can achieve this?
Edit: The main issue is when the ball is next to the depression, but it has speed that is 90 degrees from the hole, then it starts going in circles and takes a while to stop.
Ok, after getting some advice in the comments, and experimenting, this is the way I solved it:
Apply a small measure of strength towards the depression
If the current velocity is more than 30 degrees away from the center of the depression, slow the ball (apply strength in the opposite direction of the velocity)
IF the ball gets very near the center of the depression, stop it and place it in the center
Thanks for all the tips. If anyone comes up with a better way, I'm still open to suggestions.
I'm using the first person controller for my characters movement. On a left arrow keypress, I'd like the character to instantly rotate 90 degrees and keep moving forward. Currently, when I hit the arrow key, the character makes the sharp 90 degree turn, but the forward momentum the character previously had takes a second to wear off so the character ends up sliding in the direction he was previously moving a short bit.
The closest example I can think of to visually explain what I'm trying to do is how the character turns sharp in Temple Run. How my game is currently working, if I had the character on a ledge make a sharp left turn, he'd likely keep the original momentum and slide off the edge right after he turns.
Since my character is running on the x/z axis, I'm wondering if there would just be some way to maybe swap the directional velocity/momentum? The speed the character had on the x axis would instantly be switched to the z when it turns and the other would be set to zero. I'm obviously open to any solution that accomplishes what I'm looking for.
I dug into the CharacterMotor class in the first person controller, but have yet to find what part I can tweak to accomplish this.
I'd greatly appreciate any help.
Thank you.
You can try to stop the velocity of the Rigidbody before turning.
this.rigidbody.velocity = Vector3.zero;
this.rigidbody.angularVelocity = Vector3.zero;
If you want the object to continue like it did, you can try playing around with it by saving the current velocity in a variable, setting it to 0, rotate it and then putting back the old velocity (still forward).
If it works with global vectors (so from the point of view of the world, not the object), then you can try negativing the velocity, actually causing it to go 'backwards'. I can't test it for now but either way I think you need to set the velocity to zero first before turning the character.