This is my cocos2d screen. And i wanna add eraser.(not clean just erase the lines like an eraser).The background is image. So it shouldn't be erased.How can i do that?
Edit: i used this code. https://github.com/krzysztofzablocki/smooth-drawing
Yatanadam, I think your original question is quite broad and to be able to solve all your problem it would require someone to understand all the code of the sample you want to use. You would find an answer faster if you asked for specific pieces of the code or provided more information about the sample.
I did a quick check and in the class LineDrawer.m there is a method called draw, that first calculates the points needed for the curves you want and then calls drawLines to do the actual job of drawing. You could try to calculate which points need to be eliminated and then delete them from the array points. Every time the user touches the screen to erase you would need to delete points from the array to make it work.
Still, what you are asking requires a deeper understanding of the sample
Related
I want to try to have a sprite kit node move through this image and when it contacts one of the blocks it executes a function and is blocked from moving forward, but it can pass through the gaps. The way my code is set up now however, the entire image is recognized as one node so nothing can pass through even the gaps. I was wondering if anyone had some suggestions on how to work around this without having to add each individual block as its own node. Thanks.
Sorry to disappoint you but what you want to do is not possible. I know of 2 ways to detect collisions.
1) through physics like you are already doing
2) through use of intersects(_:)
Both of them require you to have separate objects. Else how is the system supposed to know the difference between the space in-between the objects and the objects them selves. Your saying you want one massive object. Maybe you could write some great script that detects intersection of different colours, but that would be a really strange solution to a simple problem
Like Steve asked. Why do you not want to add them individually? It's really easy to do. Just create an instance of the object then add it multiple times with different positions. If you are not sure how to do this then, this is the question you need to be asking.
Ok, I've done some reading around the subject, have an idea of how I'd tackle my problem, but want to find out of this is the most efficient way, or if I'm missing something simple.
I have a line diagram of a section of railway that I'd like to plot the users location onto (the user being someone on a train moving up/down the railway).
Now, I initially went down the route of geo-referencing, but quickly realised this probably wasn't the way to go, as my image is not a real reflection of the area + I want the line diagram to be what the user sees.
OK, my though process of how I will tackle it:
I know the physical area so I could extract the coordinates along the railway, every x meters (my line diagram has a resolution of around 5m). Stick this into an array. Can anyone suggest a tool to do this?!
Allocate my line diagram a start and end, then match the image coordinates with the physical coordinates for the entire line.
Read in the users position and update where to draw the position based on the closest match in the array?
Does this sound doable, and would it give me decent results?
If you have more sophisticated answers, please do share.
It sounds reasonable in general. As the user is supposed to be on a train a simpler option may work where you just keep track of the physical distance moved and use that as a percentage distance along the line. This is a lot simpler to manage and could be backed up with some coordinate checkpoints to ensure you don't have a drifting error. I'd aim for a simpler implementation if you can.
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.
What I basically need to achieve is a Fruit Ninja - style "slash" effect, where the "slash" trails the user's touch and follows the shape of the user's gesture, and is thinner the longer the distance the user has swiped.
The simplest way to achieve this seemed to be to collect all the points the user passes through in a UIBezierPath, and "stretch" an image through the length of the BezierPath. This would achieve the kind of "trailing" effect I was looking for and also ensure that the line is thinner if the distance travelled is longer.
However I can't seem to find a way to actually implement this. Is this even possible?
Alternatives? Thanks.
P.S: This is for a low-medium priority section of a regular app and not a game, so I would like to avoid having go down to OpenGL and spend a lot of time to achieve this (with completely custom drawing, etc). Something at the SDK level would be preferred, and if that's not possible at all, we'll just figure out a different UI.
Thanks!
For pretty easy-to-use stretching teqhniques of images/views you could look into
https://github.com/hfossli/AGGeometryKit/
I recommend trying to draw using CoreGraphics. See this link
http://www.effectiveui.com/blog/2011/12/02/how-to-build-a-simple-painting-app-for-ios/
Okay. Maybe you can use this.
https://github.com/hfossli/AGDraw
Just something I wrote a while ago. Hit clear and try to draw something (clear will toggle between two types of strokes). You'll see the width of the penstroke will increase with the velocity you use.. I guess that fits your need. If you fix some bugs, please make a pull request. You are free to use the code, but I will add a MIT license later.
At first I think my question should have been asked before, but I didn't find what I want.
One element of this iOS app I'm developing is break a 8x8 grid into Tetris pieces (every piece is made of 4 blocks). Two particular question I have are:
what is the best way to represent a Tetris piece in objective-C?
what algorithm to present the grid into random Tetris pieces (and later on how to check if two pieces fits together).
Edition on 01/28
#livingtech, I think I implemented pretty much what you say, except the point of "having a hole". My code works with no hole at simple stage when Tetris block is two blocks only (yes, two squares, connected either horizontally or vertically), but at 3-square Tetris block, I would get holes. I just tested and out of 1000 running, I would get one without a hole. So definitely I need some mechanism to check if next square will be a singleton.
I been trying to do the same thing for my game. Though I am a total beginner, and I'm using XNA and C#.
But the way I'm trying to go about it is: 4x6 grid array
--y123456
X1-000000
X2-000000
X3-000000
X4-000000
Here,
0 signifies no block
1 defines a block
Algorithm
Start by taking the very first 0 in the array ( top left corner )
and randomly pick a 0 or a 1.
Randomly choose the coordinates based on x1/x2-y1/y2, decide 1 or 0.
If it is 1, then decide coordinated based on where that 1 was put.
If it was 1 on x2 y1, then decide if a 1 should go on next touching
coordinate.
If you just have to code in what coordinates touch and which don't,
and the logic will roll through.
I have mine set up bit different. But this is the basic foundation of my random Tetris engine.
I also found that making it like that really helps to have a whiteboard and make a drawing of the grid and label with your coordinates.
since ur board is 8*8, i think u can use a int64 to represent the board. each bit of the int64 represents whether the specific grid is filled or not.
Implementing Tetris is a hobby of mine. First implemented it in Windows/C. Then in Perl/Tk! Last implementation I did in Obj-C/Cocoa (Mac). In all cases, the game logic is the same. Only the UI stuff changes. I treat every little box separately and have a two-dimensional array which contains the presence (and color) of every "set" box on the board. Standard board size I use is 10 boxes wide by 20 boxes high.
Separately I keep track of the "dropping" piece: it's location and what kind of piece it is. Based on a timer, try to make the piece drop. If any of the boxes where the "dropping" piece would drop is already set, then stop dropping the piece and add the piece boxes to the "set" part of the board. Create a new piece, and start over.
It may not be the best way to implement it, but it makes sense in my head. From a pure OO perspective, each shape of a dropping piece could be a subclass of a generic shape class. Override functions that check whether the shape can drop, the offsets of the individual boxes in the shape, etc.
I don't think anybody has taken a stab at your question #2 yet here, so I'm going to outline what I would do.
Setup:
You'll need to represent your grid as an array of some kind. At the very least, you'll want some kind of boolean values, to denote whether each coordinate in the grid is "occupied".
You'll need to keep track of the pieces on your grid. This could be another array, this time holding references to the four coordinates for each piece.
You'll need a variable or variables to keep track of a coordinate in your grid where you'll start filling in pieces, (I would probably populate these with a corner to start).
Set up a "pool" of all possible Tetris pieces and rotations. (You'll want to keep track of which ones you've already checked on every iteration outlined below.)
Iterate:
Get a random piece from your pool that will fit into your starting coordinate. (If you want to get fancy, you could be smart about which ones you choose, or you could just go totally random. As pieces don't fit, mark them checked, so you don't keep checking randomly forever. If you get to a point where you've checked all the pieces, you have a solution that doesn't work, either back up an iteration, or start over.)
Make sure the Tetris piece you selected didn't leave a "hole", or empty space with less than 4 squares. (I don't know your requirements for solving this problem, so I can't say whether you should focus on speed or ease of coding, but you may be able to skip this step if you want, and "brute force" the solution.)
"Place" the piece, by writing it to your piece array and marking the coordinates filled.
Check for "finished" condition, in which all your spaces are filled.
Pick a new coordinate in your grid and repeat #1. (I would pick an empty one next to the previous coordinate.)
If this actual yet, I wrote test tetris app on Objective-C few months ago https://github.com/SonnyBlack/Test-Demo-Tetris . I think my algorithm not very well, but it working. =)