I'm trying to implement a feature that allows the user to draw Curved lines whilst doing a drag gesture in Corona and so far have only been able to draw straight lines.
Can the community assist me with any code or links to tutorials that can assist me in implementing this?
Well you could do a curved line as a series of short straight lines, using an enterFrame listener to get the touch point each frame.
More generally, make sure to look at the Martian Control example for how they draw lines:
http://blog.anscamobile.com/2010/12/martian-control-another-open-source-game-made-with-corona-sdk/
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Hi I'm making a baseball app and I want from users to input strike zone on a grid like this:
How can I build the visual part so that I won't have too much trouble with implementation of a tap gesture recogniser. It'll be great if I can make this resizable so it will look great on many different devices.
With the touch gesture I need to handle so kind of recognizing position in two ways.
In which section the touch was detected.
What are the approximate coordinates inside this section.
This data will be saved on a cloud and can be later used to show the dot on this grid on other devices.
Is there a way to detect touch in a non rectangular shapes? Maybe with Bezier Paths.
Do you have a suggestion how ti appear on screen without using whole grid as a image. I'd rather divide it in Outer grid and the Inner grid somehow and than create all the pieces in each of this grids. 8 pieces in outer and 9 in inner grid.
You can start with UIBezierPath and its method containsPoint:, although this method "does not take into account the line width used to stroke the path." (link), it is also true for UIBezierPath.
Refer further to this article.
If I have a sprite node, just a white circle somewhere on the screen, how am I able to make it so when I drag, let's say downwards and slightly to the left, the circle sprite would launch upwards and to the right and then gradually come down, like a golf shot.
Another way of explaining the mechanic is the Angry Birds game, where you launch the birds of the slingshot, the birds move in the opposite direction of your drag and gradually come down.
For another live example of the mechanics of the circle, look at the app, Desert Golfing.
Thanks, and if you don't know what I mean just comment and I'll try to explain it better.
OPTIONAL: If you do know how to do the slingshot type mechanic for the circle, do you also know how to add an arrow to the screen so users know which way the circle will launch?
Ill try to break your problem down into small steps that you could then solve yourself:
Detect the swipe:
use a UIPanGestureRecognizer. You will be able to implement a method that is called whenever a user drags their finger in a certain direction.
Here are some good references:
- Pan Gesture Official Documentation
- A very useful question that can serve you as a guide
Detect the magnitude of the swipe in order to impart an impulse
Check out the second link above. What you have to do is in the method for the gesture recognizer you will detect certain flags such as when the user starts the pan or ends the pan. Then, you can check for the location at those moments. With the Pythagorean theorem you should be able to get the distance and use that as the magnitude.
Apply impulse:
Create a physics body for your sprite and then make sure that you have gravity set inside your physics world. This allows the sprite to move in a parabolic motion. Then, use applyImpulse: on your physics body with your magnitude.
Regarding the arrow, you can easily do some delegation from within your pan gesture handler that gets the magnitude of the swipe and projects a reflection that your arrow will then show. Your question is pretty loaded so going into more detail is impossible, but best of luck. Hope this helps!
When I touch a UIView with the base of my finger tip, and get the touch point using touches anyObject, I get a single touch point, even though the base of my finger tip has an area that touches a lot many points. Is there a way to get all those points? If there is no such way, how are simple paint apps implemented in ios?
You are getting the only point / touch. Each touch is related to a single finger. This is controlled by iOS.
'Simple' drawing / painting apps use the path traced by the touch points together with the current line drawing width and texture to create lines or bezier paths.
If you're trying to create a drawing app with some form of pressure sensitivity then you'd need to integrate with a 3rd party stylus (like this one)
I'm trying to draw lines in Cocos2d using touches.
I had a system where it would just add a small sprite where you touched, but it's working terribly. So I've been trying to find a way to draw actual lines using a method like ccDrawLine, but every tutorial I find seems to leave out something, and I just can't figure it out.
I've found this tutorial, Drawing line on touches moved in COCOS2D but I don't understand a few things about that.
It seems to reference the same variable from two different files, so I don't understand how it's doing that. (The naughtyTouchArray variable)
I can't find a complete guide on drawing lines, so sorry for the codeless question, but I'm getting frustrated.
Thanks.
The answer you've linked in your question provides good solution to your problem. There is no "two different files". Just two different methods of one layer. One method (ccTouchesMoved:withEvent:) handles touches and fill the array of points to be connected to each other one-by-one with lines. From cocos2d documentation, all drawing must be placed in the draw method of the node. So, another (draw) method just draws lines according to the given array. Cocos2d is based on OpenGL and it fully redraws scene every tick, so you cannot just draw new line. You had to draw all of them.
Or any other node can draw your array in it's draw method, so you can simply pass stored array of points from the layer, that detects touches, to this node.
I would like to draw a free hand polygon with one finger on top of a Mkmapview. I know how to draw a free hand polygon on a UIView and I know how to bring up a mkmapview.
I don't know if I can use the overlay function because I need to draw the polygon when my finger moved. I assume that this involves multitouch event and drawRect but i can not make it work when I put them together.
Thanks in advance if someone can help.