I would like to draw a slash animation between 2 points that I have already randomly generated.
The animation can be as simple as the line extending to the other point over a set amount of time. I would like the animation to be a "pretty" line so I was using a bunch of images and iterating over them and not just canvas.drawLine(x, y, u, v, paint).
The main issue I am running into is the points are not always the same distance apart or same direction. Im not sure if having a set number of animation sequences would work because of those differences. What is the best way to do this?
Not sure if this has been answered, but you'll have to say how complicated your imagery is. If it's a simple slash line, then drawLine would work. You'll also have to say how you are animating the line, like Android XML or if you are using some sort of timer.
There's so many ways to do this. If it's a simple line, you can use math to increment some coordinates. Watch out for using frame counting, where you say "increment the animation for the frame". It's a quick-and-dirty way to animate, and sometimes will get the job done.
A lot of video games use time-based drawing. "If this amount of time has elapsed since the last draw, draw this much". The result looks much more natural and the same between devices with different amount of horsepower.
There's also what you are drawing on. Are you using a View or a SurfaceView? The list goes on.
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im new to this android things. And i have to develop an application that can help an autism to learn numbers. I have a few ideas and I've been trying to learn and implement the code. But it's failed. The question is how can i apply the motion code or sprite to draw a numbers or letter? For example like this, i wanna make the penguin move through the line and draw a number nine.
There is example from mybringback.com which is the image move to draw a rectangle. How can i implement it to draw a number? Im sorry if i asking too much, i just trying to get some ideas.
I think that you should first build an utility program, in order to create the "path vector".
What I mean by path vector is simply a vector of Points (where a point has x value, and y value). And your utility should let you draw whatever you want, with a simple pen. You should draw on surface and store points when mouse is down, and ignore points when mouse is up.
Then, in the main program, you will just have to read at the path of your number/letter.
I've tried to implement something like this for the Sugar OLPC platform, without serializing path into files : I was able to draw, and to view the animation. And I used the process I've just described you.
Hope it can help you.
P.S : I used the word mouse, but you guessed that I talk about finger ...
There are various ways to achieve animation effects. One approach that is quite versatile involves creating a custom View or SurfaceView in which you Override the onDraw method. Various tutorials can be found on this; the official Android discussion of it is here:
http://developer.android.com/guide/topics/graphics/2d-graphics.html#on-view
Your implementation will look something like this:
// Find elapsed time since previous draw
// Compute new position of drawable/bitmap along figure
// Draw bitmap in appropriate location
// Add line to buffer containing segments of curve drawn so far
// Render all segments in curve buffer
// Take some action to call for the rendering of the next frame (this may be done in another thread)
Obviously a simplification. For a very simplistic tutorial, see here:
http://www.techrepublic.com/blog/software-engineer/bouncing-a-ball-on-androids-canvas/1733/
Note that different implementations of this technique will require different levels of involvement by you; for example, if you use a SurfaceView, you are in charge of calling the onDraw method, whereas subclassing the normal View lets you leave Android in charge of redrawing (at the expense of limiting your ability to draw on a different thread). In this respect, Google remains your friend =]
So in my game my View gets drawn an inconsistent rates. Which in turn makes it glitchy. Ive been running into alot of problems with the invalidate(); meathod. Any simple ideas- Everywhere i look I get thrown up on by tons of intense code.
You haven't provided us with much information, specifically code.
A few things you could do are:
Set the initial frame rate to the lowest value you observe your application runs at, i.e., if currently set to 1/60, but the frame rate continuously dips to 1/30, set to 1/30 etc.
Rework your drawing calls to be more efficient.
Try to combine multiple transformations into a single transformation by multiplying matrices, i.e. if you need to scale, translate, and rotate, multiply those three matrices together and apply that single transformation to the vertices instead of applying three separate transformations.
Try not to iterate through entire lists/arrays if unnecessary.
Attempt to use the lowest level / most primitive structure possible for anything you have to process in the loop to avoid the overhead of unboxing.
[edit on 2012-08-27]
helpful link for fixing you timestep: http://gafferongames.com/game-physics/fix-your-timestep/
It sounds like your game loop doesn't take into account the actual time that has passed between iterations.
The problem is the assumption that there is a fixed amount of time between loop iterations. But this time can be variable depending on the number of objects in the scene, other processes on the computer, or even the computer itself.
This is a common, somewhat subtle, mistake in game programming, but it can easily be remedied. The trick is to store the time at the end of each draw loop and then take the difference of the last update with the current time at the start. Then you should scale all animations and game changes based on the actual elapsed time.
I've wrote more about this on my blog a while back here: http://laststop.spaceislimited.org/2008/05/17/programming-a-pong-clone-in-c-and-opengl-part-i/
Part II specifically covers this issue:
http://laststop.spaceislimited.org/2008/06/02/programming-pong-in-c-and-opengl-part-ii/
I have a Line class composed of two Points of two ints each that I draw with a wrapper over Canvas.drawLine().
Easy so far.
I want to have that Line drawn slowly from one Point to the other. My best guess is to make a function that will dice up my Line into an list of Lines, starting from the first Point with each subsequent Line getting longer and longer till it reaches from one Point to the other. Then, I will have a Canvas.drawLine wrapper that will take that array of Lines, and iterate over them, drawing each one with a pause of some sort in between them, giving the appearance of the line "growing".
Is there something in the android libraries that already does this and/or would this be better solved some other way?
Edit: This is android 2.1
Android has libraries for creating animations. Look into tweened animations and the AnimationDrawable class.
Or maybe you can have one line with a fixed starting point and on each draw the end point increments . I believe this approach has better performance .
I need some help with this simple animation on my Android phone. I'm a newbie with animation and graphics.
I'm graphing accelerometer data as a sliding time series window. As new accelerometer data is read, its data is plotted on the right, pushing previous data to the left, as shown below:
My program is running pretty smoothly, but I would like some help optimizing the animation. Here are my main concerns:
My current implementation reads all the accelerometer data in one thread and keeps the data in a fixed-size FIFO queue to capture the width of the time series window. I then use Timer.scheduleAtFixedRate() to plot out the entire contents of the queue so that the whole graph is re-drawn every 50 milliseconds. Can I improve upon this? Do I really need to re-draw the graph so often like this? In another similar program I've seen, each pixel column is copied to one pixel to the left, rippling down the graph; the newest data's column is drawn on the far-right pixel column. Is this better?
I redraw the legend (in the upper left) in the drawing thread that runs the draw function every 50 milliseconds. Is there any way to "keep" that legend in place instead of having to constantly re-draw it?
Any other help would be appreciated. I have heard of optimizations like double-buffering but am clueless if that would help me.
If the legend and the cross hairs only need to be drawn once, then you should place it into a buffer bitmap. For your graph line maybe try using the Path object to plot the lines. When it gets time to draw the lines just drawLine to the appropriate point and then translate the canvas left appropriately.If
I want to draw something at about 30 frames per seconds on Android Canvas or other convenient object for this purpose. In my application different graphic objects are drawn and if any of the graphic object is touched, the graphic object changes its shape. I looked at the
onDraw(Canvas canvas) callback of View subclass but calling invalidate() does not help here: first I cannot control the frame rate and second if the objects are moving too fast, the motion appears jerky.
I personally dislike Android's built-in Animation classes, so I tend to do all animations with Canvas by hand. I have found the most luck with creating a list of the images you want to use in your animation and then an int variable to store the current "frame" you are on. To advance the frame, I create a thread that sleeps for, say, 30 ms and then update the frame variable accordingly. Then in whatever update handler you are using, you can just create a switch statement or something of the like, and draw the respective frame.
It may seem like a lot of work, but it really isn't. Shove it all into a class and you will love yourself for many animations to come.