I have just started learning basics about Graphics2D class, So far I am able to draw different objects and implements ActionListener to actually move them on screen by onKeyPress. So far so good, While I thought of doing something more complicated. I want to give a path to my object and animate it on that particular path only.
Something like, I will draw a line on sky and a plane should stick with that drawn line and keep it self to fly on that particular line. Now is it possible?
I don't need any sort of code, But few different method or ideas will let me get started working on this. A visualise elaboration of my idea is as below.
Start Point :
End Point :
Now as shown above, my yellow box(in future plane) should stick with given path while animating(path grey line)
My research so far,
I have searched my buzz words such as path in java, and found Path2D and GeneralPath classes, Does anyone know if I can use that to solve this.
Thanks
Great !
It reminds me of my first steps in IT. How much I enjoyed all this simple math stuff but that make things move on screen. :)
What you need is actually a linear interpolation . There are other sorts of interpolation and some api offer a nice encapsulation for the concept but here is the main idea, and you will quite often need this stuff :
you must rewrite your path
y = f (x )
as a function of time :
at time 0 the item will be on start position, at time 1 it will reach the end. And then you increment time (t) as you wish (0.001 every ms for instance).
So here is the formula for a simple linear path :
x = xstart + (xend-xstart) * t
y = ystart + (yend-ystart) * t
when t varies, you object will just move linearly along the path, linearly has speed will be constant on all the path. You could imagine some kind of gravtity attraction at end for instance, this would be modeled by a quadratic acceleration (t^2 instead of t) ...
Regards,
Stephane
First, make the ability to move from point a to point b. This is done with simple algebra.
Second, make the ability to take a path and translate it into points. Then when you're going to do curves, you're really just moving from point to point to point along that curve.
This is the most elementary way to do it and works for most instances.
What your talking about is simple 2D graphics and sprites. If that is all you need then for Java take a look at Java 2D Sprites If your leaning more towards or will eventually go with camera perspectives and wanting to view the animation from diferent angles the go with Java 3D from the OpenSource Java 3D.org. Either way what you want is a simple translating of the object along a line, pretty simple in either 2D or 3D.
You can try going trough the code of my open source college project - LANSim. It's code is available in Code menu. It does similar to what you are trying to do.
Related
I'm working on a visualization project. From the data I have calculated the X, Y, and Z coordinates for a large set of points. Using Processing it was very simple to draw this out with lines and dots.
From the top it looks like this:
And from a side angle you can see how it occupies 3D space
The part I'm struggling with is turning this into polygons. I need the end result to be something I can export as a .obj file, and then later open in Blender or similar 3D modelling programs.
The two main issues are that these points are not on a grid, but are instead organized in a circle based on radian angles, and that the triangle structure isn't all that simple.
I tried drawing out my own polygons (it's kinda sorta working), but I'm getting to the point where the maths are getting a bit too complex to handle and my code is bloated with arrays, if statements, and for loops...
Surely there must be a better way? Are there any plugins maybe that would help me with this task? Or some techniques I should take a look at?
Processing has screenX() and screenY() functions that take a 3D point and return a 2D point. That sounds like pretty much exactly what you're looking for. Please see the reference for more info.
I started programming a game in java. I have Enemys and a Player, a basic 2D game, thats to get experience for the first time.
Now i wanted the Enemys to follow a path, which i can draw in to a "level editor".
I have a JPanel, a mouseMoveListener, and on click the Path2D starts saving the mouseMove Points to a Path2D.Double Object.
After that, i implemented the following method to make the enemys following this path:
public void forward(){
if(!pathIterator.isDone()){
pathIterator.currentSegment(current);
x = current[0];
y = current[1];
pathIterator.next();
}
else {
dead = true;
}
}
I think its clear what happens now: The Enemy is following, but the speed is that i moved the mouse with. So if i move to Mouse to fast, the enemy just.. "jumps" from one point to an other. To slow, its "sneaking" over that points. (And because im not an Robot, i cannot move the Mouse with the same speed ^^)
Talking of Robot: Yes, i could let a awt.Robot move my Mouse. But this isnt really possible too, because i have to draw complicated paths, which dont have any visible mathematics behind.
So, i want let this Enemys to move on this path with the same speed. My Problem: I don't know where to implement a "fix". I have 2 Ideas:
Maybe i could work on the Path creation: Instead of just adding the Points to the Path2D, maybe i could calculate points between the points where i moved to fast, or deleting points which are to near by each other. But: First, I don't know how to calculate this, (Is there any maths logic to achieve this?) And Second, when i do this i probably would'nt be able to change the speed of the enemys ingame, and that would be bad
The second idea i have, is to calculate the points between (oder the points to jump over), this should happen every frame, relative to the actual speed. But here im not experienced enough in maths to.
So, are that ways possible, and if yes, has someone an idea how to calculate this?
And, if not, what other possibilitys i have to achieve this?
Thank you, and sorry for the bad english!
All you need to do is define the speed of movement of the enemy inside the enemy class.
When it works out the next point to move to then create a direction vector by subtracting the current position from the new position.
Normalize the direction vector (so it is length 1) then multiply it by the speed and the tpf (time per frame).
Move by that amount instead of jumping to the next point.
(Note if the points are very close together or the framerate is low this can cause it to overshoot a bit, it should be fine though).
I'm working on a Java project witch is really killing me. After several days of researching on different forums, looking for what I really need, I come to ask your help.
My data :
A .ply file (containing a 3D shape made of a lot of triangles)
A point (3D coordinates)
I would like to know if this point is contained inside the complex 3D shape.
I have split this problem in 2 smaller problems :
How can I represent the complex 3D shape in memory? (I found several libraries, but it seems really complex for the task I want to do : Java3D, JBullet, JME3...) I do not want my java application to show the object for now.
How can I know if this point is inside the 3D shape or not? (I thought to make a 3D vector starting from the point and to count the number of intersections with the shape, but I don't see how to do and witch library can I use?)
Maybe there are easier ways to do it, that's also why I come to you.
I am really stuck now and I would like if this is possible without writing customs libraries...
(Sorry for my writing, I'm not English ^^)
Thanks for helping me.
Here is one approach. Not the best or the fastest, but once you have something working, it will be easier to improve upon.
How can I represent the complex 3D shape in memory?
Implement a quick and dirty PLY file format parser. Here is the PLY format spec. Load the data up and store it internally: an array for each X, Y, and Z. This is all just plain Java.
How can I know if this point is inside the 3D shape or not?
Define a line based on your point and some other arbitrary point. For each polygon, determine where it intersects the plane (some help) and if the intersection point is inside or outside the polygon (some help). As you suggested, then count the number of intersections to determine if the point is inside or outside your 3d shape.
I am developing an AI simulation of predator and prey. I would like to simulate the AI hiding behind obstacles, if it is being chased. But I am still trying to figure out the best way to implement this.
I was thinking along the lines of checking on which side of the obstacle the predator is on and trying to go on the opposite side. Maybe using the A* path finding algorithm to ensure that it gets there using the shortest path.
Now the main reason I am writing is in case somebody is able to point me in the right direction of implementing this (maybe somebody has done this before) or have any other good ideas how to implement it. I have never done anything like this before in terms of programming AI or making any game.
All the obstacles are either horizontal or vertical squares/rectangles.
Please note that the circle in red is the predator while the circle in green is the prey being chased.
I can't give any code off the top of my head, but I can tell you a few things:
First, you need to define the goal of this program. For this case, it is to get the AI to hide behind an obstacle, keeping the user and the AI on opposite sides whenever possible.
Next, you need to decide what needs to be done inside the code (without writing any real code) to accomplish this goal. For instance:
We need to determine what "zone" of the scene is considered "behind the obstacle"
Next, we need to determine a path for the AI to get to that zone without going through the obstacle.
Lastly, we need to add some sort of delay to this so the AI doesn't constantly change its mind for every pixel the user moves across the screen
This isn't per se an easy problem, but it is certainly achievable without breaking too much of a sweat. I'd recommend you find a way, even if it is slow and requires a ton of code, then write the code for it, and lastly refine. If you worry about refinement, then you never get any of the problem solved.
HINT: Determine a vector that points from the player to the middle of the obstacle. Then, multiply the vector by 2 and add it to the position of the player and that gives you a point on the other side of the obstacle (assuming it is a rectangle). Apply a Math.min() or Math.max() restrictor to the x and y values you get to keep the AI as close or far from the obstacle as you wish. That should be a decent start! :)
Update -- I decided to add some code!
// This assumes a few variables:
int obstacleCenterX, obstacleCenterY;
int aiX, aiY, aiWalkSpeed;
int predatorX, predatorY;
private void updateAIMovement() {
int slope_x = obstacleCenterX - predatorX;
int slope_y = obstacleCenterY - predatorY;
int destination_x = predatorX + (slope_x * 2);
int destination_y = predatorY + (slope_y * 2);
if(aiX != destination_x){
aiX += (slope_x / Math.abs(slope_x)) * aiWalkSpeed;
}
if(aiY != destination_y){
aiY += (slope_y / Math.abs(slope_y)) * aiWalkSpeed;
}
}
I have not tested anything at all, but I think this might be somewhat of a right path to take. I could have done A LOT to improve just that little code snippet, but I didn't (such as some trig to make sure the player moves at a true speed when going diagonally, etc...)
Hopefully this helps a little!
I would check if there is something crossing the direct line between x and each observer. If it is, x is hidden.
I'm currently working on my 2D game project (Java), but so far any kind of game logic or AI has been crudely implemented. For instance, say I need to randomly position a bunch of sprites a long the top of the screen, I'd be using the Random class to do this. I'd simply use Random.nextInt( size of x axis on which to spawn ); Although this does work I'd be interested to hear how I should really be going about this kind of thing.
As a second scenario (this is why I put AI in the title, although it's not really AI), say I want to have my characters randomly blink in a life-like fashion. What I'd do here is use the Random class to calculate a % (say 20% chance) of blinking and call it every second.
Any suggestions on how I should really be going about this would be greatly appreciated.
Google for a paper titled "Steering Behaviors" by Craig Reynolds. It address just this and you'll find great ideas to start with specifically some nice ideas for giving groups of sprites the appearance of 'intelligent' movement. The key for him in his different behaviors, i.e. flocking, etc. is making properties of any given sprite dependent on those of some other sprite. You could even go so far as to say, like -- any given sprite will blink only if it's two neighbors just have blinked. Something or other along those lines.
Hope this helps!
Are you using an OOP (Object-Oriented approach)? If not, you should definitely look into it. It's really simple with java and can speed up your development time and neaten your code.
I would make a sprite class, and give them a function, say actionSpawn, or actionMove (I like to start my "action" functions with the word action so they are easily identifiable). In this function you would encapsulate the Random.nextInt function, to set the sprite's x and/or y position.
You could use the same approach to make them blink.