I'm trying to figure out the best way to procedurally animate the growing of a 2D plant in iOS.
I want the plant to animate to give an encroaching feeling to the user.
Basically, to animate the growing of a branch, with little buds that will eventually animate into full grown leaves.
To breathe a little life into it, I'd also like the plant to sway a bit as it grows, rather than feeling hand painted on the screen.
One way I've thought of is to use CGPaths and Bezier curves to create the shape of the stalk and the leaves, but I'm not entirely sure how to animate the drawing of the paths. Once I get the "drawing" of the stalk, i'd like to "plant" little buds at certain points on the stalk, as the line is growing/animating and these buds will also start to grow outwards from the plant.
Any suggestions on what route to take to accomplish this task? I'd prefer to procedurally animate as opposed to hand drawing each frame and animating that way. My reasoning is that I imagine procedurally animating will be less time consuming, give me more control over different aspects of the animation, and be reusable in other projects (not to mention, it will be fun to program!)
I've come across this blog posting for the drawing of animated lines:
http://oleb.net/blog/2010/12/animating-drawing-of-cgpath-with-cashapelayer/
Perhaps this would be a starting approach for achieving the results I want, I need to sit down and go through the code he posted.
Also, maybe this is something that would be easier to do using cocos2d or something similar? Or perhaps quartzcore and core animation will work fine.
Thanks for any suggestions you might have, any information is helpful at this point.
(Great question! Posting this as a "community wiki" since it is not an answer but just some references and I didn't want the links to get screwed up in comments. Perhaps people want to add to this?)
I did a simple search on "procedural tree branching code" and there were lots of interesting hits - really rich area.
A post on gameDev.stackExhange pointed to this great resource: Algorithmic Botany
Also Snappy Tree is pretty amazing and the source code is available.
These two also sound interesting:
TReal is a program capable of generating realistic 3D tree models.
Arbaro is an implementation of the tree generating algorithm described in Jason Weber & Joseph Penn: "Creation and Rendering of Realistic Trees" written in Java.
Perhaps more accessible to the OP and with a less complex result are these actionScript tutorials on fractal trees. ActionScript drawing code is pretty easily translated to Core Graphics.
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I want to make a 2D model in iOS programatically. Like this:
This is taken from the app Gomoji.
I googled it but not get the proper solution.
This character is also moving so it can move hands and the legs meanwhile I want to change the colour of the hands etc.
Could it be possible with SpriteKit, SceneKit, gif, SVG or anything else?
This is an incredible amount of work in code, with SpriteKit and actions.
You might be better off using the puppet features of After Effects to creation motion frame sequences, and then bring them into SpriteKit and string them together and jump between the sequences as necessary.
Start here, to understand the puppetry tools in AE:
https://helpx.adobe.com/after-effects/using/animating-puppet-tools.html
Once you've learnt the lingo, head on over to youtube to pick up tips on how to do 2D arms, head wobbles, etc.
There's also a face animator in the latest versions of After Effects, that might be helpful, too.
Generally speaking, this is still a lot of work. And a lot of fiddling to get it to look "just so". But doing this visually, with manual mouse controls and instant playback before exporting image sequences from AE will be lightyears faster than attempting to do this with joints and code in SpriteKit or any other game engine.
New user to the site, but I have used it in the past so I felt it best to ask my question here, for the best chance of getting a response.
What I'm dealing with is one object, this being the sprite for my latest app, which I need to check for when it comes in to contact with another object, in this case, a tunnel which will curve.
Now, I'm aware of CGRectIntersectsRect, however I can't see that being helpful, as if I've got 2 UIImages, that being the top and bottom of a "mountain", and said pieces curving, there's no doubt that the sprite would touch the "rectangle".
What I need is something to trigger when the sprite hits the actual wall, however my limited knowledge of Objective-C isn't helping my case.
I imagine someone out there will know what I can do to resolve this, as for all I know it could be a simple solution.
Thank you in advance everyone!
First, I'd probably not build these basic pieces yourself. For iOS 7, you can use SpriteKit, which is built-in. If you want to support older versions of iOS, look at cocos2d (it's good for iOS 7, too).
But to the question, one approach for detecting arbitrary overlaps is to draw both objects into a buffer and check if there are any overlapping pixels (for instance, by drawing one in in pure red, and another in pure green, and then looking for pixels that have both). For a discussion of how to do this kind of thing in Core Graphics, see Clipping a CGRect to a CGPath, which provides sample code for the simplest version (checking for the intersection of a rectangle and curve), but the same approach can be used more generally. Note that this drawing can get expensive if you're doing it constantly, so usually you first check whether the bounding rectangles overlap. That tells you whether it's even worth the trouble to look closer.
But first I'd look at SpriteKit.
let's say I want to display a customizable (2D, cartoon-like) character, where some properties e.g. eye color, hair style, clothing etc can be chosen from a predefined set of options. Now I want to animate the character. What's the best way to deal with the customization?
1) For example, I could make a sprite sheet for each combination of properties. That's not very memory efficient and not very flexible, but probably gives the best performance.
2) I could compose the character from various layers, where each property only affects one layer. Thus, I could make a sprite-sheet for the body, a collection of sprite-sheets for the eyes (one for each eye color) etc.
2a) In that case, I could merge the selected sprite-sheets in order to generate a single sprite-sheet containing the animation of the customized character.
2b) Alternatively, I could keep the sprite-sheets separate and try to animate them simultaneously as layers. I fear, that this might become a problem performance-wise.
3) I could try to modify the layers programmatically, e.g. use a sprite-sheet for the eyes as a mask and map some texture on it before merging it down to a single sprite-sheet. I would think this is a very flexible approach when it comes to simple properties like eye colors, but might become difficult for things like hair-style. I am aware that this depends much on the character and probably a general answer is difficult.
I assume that my problem is not new, so there is probably a standard approach to it.
Concerning the platform, I'm particularly interested in iOS and try to avoid OpenGL (well, I'm open-minded). Maybe there is a nice framework that can help me here?
Thanks!
Depending on what your working on, you might want to animate part/all of the animations outside in another tool, such as flash. It is much easier to work with a visual environment.
Then there are tools that take swf files, and create sprite sheets that you would then animate in cocos2d.
That is a common game creation workflow.
You problably want to take a look on how to create sprites at cocos2d.
Cocos2d comes with a set of tools that help you to animate single parts and offers abstractions to compose parts (like CCBatchNode or CCNode). Also, it comes with tools that helps you to pack sprites into sprite sheets (e.g Texture Packer) and develop levels (e.g Level Helper).
Cocos2d is an open source framework and it is widely used. You also have cocos3d but I never used it :).
I've never done OpenGL, but I'm looking for some pointers on this particular question on an AR app I'm practicing with.
I'd like to make an app with a "flat rectangle" along with text written on the surface of the rectangle. Visually, I'm imagining something along the lines of a piece of paper with text written on it. Each time the app starts, the text would be something different (the text is pulled from a plist file).
The user would be able to view the paper from all sides, much as if there was a piece of paper hanging in front of him.
Is this trivial to do in OpenGL? How could I get started?
Sorry for the really open-ended question, but I wanted to get a feel for how this kind of thing is done.
Looking at the OpenGL template source code in the Xcode sample projects, I see that there is a big array of vertices. I presume that to create a "flat" rectangle, I'd essentally just have to remove or make the z-axis zero. And then the dynamic text that will attach to the surface of the flat rectangle...I dont have any idea how to do that......
This question is hard to answer unambiguously. In general, this is trivial, but then again it is not.
Drawing a "flat rectangle with something on it" is a couple of API calls, as simple as it can get. Drawing text in OpenGL in an efficient way, and high quality, and without big preprocessing is an entirely different story.
What I would do is render text using whatever the "normal system-supported" way is under iOS (just like you would draw in any window, I wouldn't know this specific detail), but draw into a bitmap rather than on the screen. This should be supported, pretty much every OS has supported this for at least 10-15 years. Then turn this bitmap into a texture, bind it, and draw your trivial flat quad with OpenGL (set up a vertex buffer with 4 vertices, each vertex a texture coordinate, and draw two triangles - as easy as it gets).
The huge advantage of that is that you get to use the installed system fonts (or any fonts available), you don't need to generate a bitmap font and don't need to think about really ugly things such as hinting and proper spacing, and it's much easier to mix different text styles, etc. OpenGL has built-in support for text too, of course, but it is not terribly efficient or nice either. If the text does not change every millisecond, it's really best to render it using the standard renderer that the operating system provides (yes, that probably won't be hardware accelerated, but so what... since the user must read the text, it likely won't change every millisecond).
Now it gets more complicated if your "piece of paper" should bend and twist too, or do a page peel effect rather than being just a flat rectangle. In that case you need to tesselate it, which can be harder than it sounds, too. Not all tesselations look optimal for all bends/twists, or they do but do not have the optimal (read as minimum) number of vertices.
There is an article on "page peel" and such tesselation in one of the GPU Gems or GPU Pro books, let me search...
There: Andreas Bizzotto: "A Shader-Based eBook Reader - Page peeling effect", GPU Pro2 pp. 278-299
Maybe you can get hold of a copy or are lucky enough to find it on Google Books or something.
I wanna achieve something that looks like the wizard's ability in the game Trine.
I want to create a game where the player uses the mouse to create certain objects, so i will need to compare the shape the player drew to a predefined shape of my own and check if its close.
I have no idea how to achieve this and where to look for, I assume it has something to do with shape recognition like in image processing and computer vision but it should be much simpler and work in real time.
does anyone have a clue how this can be done or where can i look for something like that?
Is this what you're going for? http://www.youtube.com/watch?v=7Zh79q_xvZw
I would start by researching gesture recognition. I think that's the phrase you need to get good info. http://en.wikipedia.org/wiki/Gesture_recognition
Also, sketch recognition: http://en.wikipedia.org/wiki/Sketch_recognition
Have a look at this question. What you are looking for in particular is on-line handwriting recognition, meaning that you follow every move of the user from beginning to end.
Now, you might want to simplify it a whole lot, so one way is defining 9 areas, like a 3x3 grid. Then convert the user's movement into a list of how the user moved through these grids (use thresholds to make sure it was in that area for a while). Now you will have an array like this: 1-1, 1-2, 2-2, 2-3 (meaning the user went from upper-left corner, the upper-middle, etc.)
This information is now fairly easy to match to a set of gestures. If it performs poorly, you can either make it more difficult and introduce a Hidden Markov Model, that will allow some mistakes in the gesture (but still matching the most likely one you have in your gesture set), or you could simply display the grid to the user, so that the user will learn the gestures like number codes.