b2Body* foundation =[self createStaticBodyAtLocation:CGPointMake(15, 15) withSize:CGSizeMake(35, 35)];
b2Body* beam=[self createDynamicBodyAtLocation:CGPointMake(105, 35) withSize:CGSizeMake(150, 10)];
b2RevoluteJointDef revoluteJointDef;
revoluteJointDef.Initialize(foundation, beam, b2Vec2(30.0/PTM_RATIO,30.0/PTM_RATIO));
_world->CreateJoint(&revoluteJointDef);
The above code creates a static and a dynamic body and then joins them with a revolutejoint. Here's what I get:
Then I add the following lines to add another body, which is a static circle and then join the circle and the previously added bar on the other end of the bar.
b2Body *jointBall=[self createCircleAtLocation:CGPointMake(160, 135)];
revoluteJointDef.Initialize(jointBall, beam, b2Vec2(100.0/PTM_RATIO,10.0/PTM_RATIO));
_world->CreateJoint(&revoluteJointDef);
But here's what I get:
After adding the circle, I can't move the bar. It's fixed. But I'd expect it to join to the circle. I've tried to change the anchor point to different positions but it doesn't help. What am I missing? Maybe it is not possible to join a dynamic body to more than one static bodies.
From the box2d manual:
All joints are connected between two different bodies. One body may be static.
You may manually move static bodies, but you should be careful so that you don't squash dynamic bodies between two or more static bodies
What you've effectively done here is squash the bar body between two static bodies with revolute joints. Static bodies cannot move at all, so the output you're seeing actually makes sense. The first revolute joint (connecting box and bar) allows the far end of the bar to move (rotationally). However, when this far end is connected to another static body by another joint that restricts all motion but rotation, it cannot move anymore. Thus, it makes sense that the rotation of your bar body will become fixed after joining it with two different static bodies.
I searched through the box2d code and didn't find anything that directly sets the rotation of a body connected via a joint.
What are you trying to do? It seems like you might be trying to have the ball move along with the end of the bar, in which case I would recommend making the ball a dynamic body (so it can move). Also, depending on what you're doing, a weld joint might be more appropriate.
Related
I am trying to create multiple SKSpriteNodes that each have their own independent variables that I can change/modify. I would like to be able to run a function when the app starts, for example "createSprites(5)" which would create 5 sprites with the image/texture "shape.png" at random x and y coordinates and add all 5 Sprites to an array that I can access and edit different Sprite's positioning based on the index value. I would then like to be able to have another function "addSprite()" which, each time it is called, create a new Sprite with the same "shape.png" texture, place it at another random X and Y coordinate and also add it to the array of all Sprites to, again, be able to access later and change coordinates etc.
I have been looking through so many other Stack Overflow pages and can not seem to find a solution. My ideal solution would simply be the two functions I stated earlier. One to create an "n" number of Sprites and another function to create and add one more sprite to the array each time it is called.
Hope that makes sense, I'm fairly new to Swift and all this Sprite stuff, so simple informative answers would be very much appreciated.
You're not going to find an ideal solution from the past because nobody has likely had exactly the same desire with both Swift and SpriteKit. Having said that, there's likely partial answers you can blend together, and get the result you want or, at least, an understanding of how to do it.
Sprite Positioning in SK is probably the first thing to read up on:
https://developer.apple.com/library/content/documentation/GraphicsAnimation/Conceptual/SpriteKit_PG/Sprites/Sprites.html
having gotten that figured out, you can move to random positions.
Random positioning of Sprites:
Duplicate Sprite in Random Positions with SpriteKit
Sprite Kit random positions
Both use earlier versions of randomisation that aren't as powerful as what's available now, in GameplayKit. So... Generating random numbers in Swift with GameplayKit:
https://www.hackingwithswift.com/read/35/overview
It's hard to overstate the importance of understanding the various possibilities of game design implications of varying types of randomisation, so probably wise to read this, from Apple:
https://developer.apple.com/library/content/documentation/General/Conceptual/GameplayKit_Guide/RandomSources.html
After that, it's a case of needing to determine what constitutes a time or event at which to create more sprites at more random positions, and how fussy you want to be about proximity to other sprites, and overlaps.
I am working on an animation in AS2 which requires that all text MovieClips (instance names starting with "txt_") will be manually placed initially on stage and I need to store their own initial placed positions (x,y) so they will be retrievable later when I want to animate them to these same final coordinates regardless of where they move around in the meantime.
So the following steps needed:
All these text movieclips are placed on stage manually from library (not dynamically) matching their expected target keyframe end position (x,y) to get desired final screen layout.
Then a frame script loops through all these MovieClip instances on stage before rendering them on stage and stores their initial (also future target) (mc.targetPosX or mc.targetPosY) positions.
Then frame script also moves all of these MovieClip instances before rendering them on stage and moves/offsets them elsewhere on stage (eg. mc._x +=25px;) and hides them (eg. mc._alpha =0;)
Finally by using a tween like Greensock I want to use their stored target end position to animate each of them to their stored final target position.
(eg. TweenLite.to(mc, 1,{_alpha:100, _x:mc.targetPosX, ease:Quad.easeOut});)
I was able to create a loop to get "txt_" movieclips but then I don't know how to save their target positions with their instance and use them outside the loop afterwards.
Thank you in advance,
Attila
I don't know what problems do you have trying store some variables inside instances, but here my suggestions about proccess you described.
First of all we have loop which do all thing you described at question.
To do so we must have some list of you mc's or pattern to make this list dynamically. From you question i suppose that you use this kind of loop.
for(var i=0, txtCount=10; i<txtCount; i++){
textMc = this['txt_'+i];
//do stuff
...
}
From here on your points.
You already did it.
Use loop described above to store current object properties inside his instance
textMc.storedX=textMc._x;
textMc.storedY=textMc._y;
Here is same loop place object wherever you like
textMc._x+=25;
textMc._alpha=0;
Finally right after that in the same loop use greensock.
TweenLite.to(textMc, 1,{_alpha:100, _x:mc.storedX, ease:Quad.easeOut});
That's it.
I'm using PostGIS on ruby/rails, and have created a simple box-like polygon under which I wish to search for land parcels in a county. The st_overlaps tool has worked for this before and it has worked this time, sort of.
So I created the polygon to search for parcels (multi-polygons, as it turns out) underneath it
factory = RGeo::Cartesian.factory
coords = [[1554780, 1101102], [1561921, 1062647], [1634713, 1097531], [1630867, 1140657]]
points = coords.map { |pair| RGeo::WKRep::WKTParser.new.parse("POINT (#{pair.first} #{pair.last})") }
ring = factory.linear_ring(points)
polygon = factory.polygon(ring)
After running the active record call:
Parcel.where{st_overlaps(:parcel_multipolygon, polygon)}
I get 157 results. Far less than expected. I exported them a kml file using a custom script of mine. I will upload it soon for viewing.
What you'll see in that kml once loaded in Google Earth, is a parallelogram of pins marking parcels whose areas (polygons) are clearly saddling the outer ring of the parameter-polygon I created to search under. There are so many parcels along these invisible lines in such a clear, distinct shape, the fact that there are no pins in the middle of the shape clearly indicate that the search results were only at the overlappings of parcel multipolygons with the exterior edges (LinearRing) of the search polygon.
Based on my re-reading of the documentation for st_overlaps, I'm left puzzled as to what seems to be the problem here.
Here's a link to view the kmz export. (coordinates converted to geographic before export). You can view it in your browser. The search-polygon itself is not included, but its easy to see where its exterior ring is
https://docs.google.com/file/d/0B5inC0VAuhH1TXdTbWQ2RngxZk0/edit?usp=sharing
I think it is behaving as expected. St_overlaps will give features that actually lie on top of each other. If you want all features inside the polygon try ST_Intersects.
I'm trying to combine several UIBezierPath drawings.
I have different types of drawings I can make (line, cubic bezier, quadratic beziers), and each of these can be filled or unfilled. I'm selecting the drawing type randomly, and my goal is to make 3 different drawings which are connected at a point.
So where the first, say, line drawing ends, the second path - maybe a cubic bezier — begins. Where that ends, a third, maybe a filled line drawing begins.
I've got a square UIView that I'm trying to draw this in, and each path should have its own part of the UIView: the first 1/3rd, the second and the third.
Would I be able to create this with one UIBezierPath object, or do I need to create 3 different ones? How to make them end and start at the same point? Is there a way to do this with subpaths?
UIBezierPath has its instance methods like (DOC)
-addLineToPoint:
-addArcWithCenter:radius:startAngle:endAngle:clockwise:
-addCurveToPoint:controlPoint1:controlPoint2:
-addQuadCurveToPoint:controlPoint:
-appendPath:
You can combine paths one by one. When you've done, use -closePath to close the path.
Feel free to take a look at my open sourced lib which called UIBezierPath-Symbol. ;)
And if you want more customise path drawing, I recommend CGMutablePath. You can create each path as complex as you want (you can combine simple paths by CGPathAdd... methods). Finally, use CGPathAddPath() to combine them together.
void CGPathAddPath (
CGMutablePathRef path1, // The mutable path to change.
const CGAffineTransform *m, // A pointer to an affine transformation matrix, or NULL if no transformation is needed. If > specified, Quartz applies the transformation to path2 before it is added to path1.
CGPathRef path2 // The path to add.
);
You can combine paths like this:
UIBezierPath *endPath = [UIBezierPath bezierPath];
[endPath appendPath:leftLine];
[endPath appendPath:rightLine];
[endPath appendPath:midLine];
A UIBezierPath is just a wrapper for a CGPath, which itself is just a set of instructions for drawing (by stroke or fill, or both). That drawing can take place anywhere. In other words, a UIBezierPath is just a tool for drawing; the important thing is the drawing itself. Given a graphics context (which might be a UIView, a UIImage, a CALayer, whatever), you can do as much drawing as you like in succession - say, a line, then a cubic bezier, then a filled line drawing. But how you perform those drawing bits is totally up to you. You shouldn't really care whether you do it with three UIBezierPaths, one UIBezierPath, multiple paths, one path, subpaths, whatever (or even by copying other drawings into this one) - the final effect is all that matters, i.e. the accumulated drawing ultimately done in this graphics context.
Your question is like asking, "Should I draw this circle with my right hand or my left hand, and should I draw it counter-clockwise or clockwise?" It doesn't matter. Once it's done, what will have been drawn is a circle; that is what's important.
I have completed an image processing algorithm where I extract certain features from two similar images.
I'm using OpenCV2.1 and I wish to showcase a comparison between these two similar images. I wish to combine both the images into one, where the final image will have both the images next to one another. Like in the figure below.
Also, the black dots are the similarities my algorithm has found, now I want to mark them with digits. Where, point 1 on the right is the corresponding matching point on the left.**
What OpenCV functions are useful for this work?
If you really want them in the same window, and assuming they have same width and height (if they are similar they should have same width and height). You could try to create an image with a final width twice bigger than the width of your 2 similar images. And then use ROI to copy them.
You can write a new function to encapsulate these (usefull) functions in one function in order to have a nice code.
Mat img1,img2; //They are previously declared and of the same width & height
Mat imgResult(img1.rows,2*img1.cols,img1.type()); // Your final image
Mat roiImgResult_Left = imgResult(Rect(0,0,img1.cols,img1.rows)); //Img1 will be on the left part
Mat roiImgResult_Right = imgResult(Rect(img1.cols,0,img2.cols,img2.rows)); //Img2 will be on the right part, we shift the roi of img1.cols on the right
Mat roiImg1 = img1(Rect(0,0,img1.cols,img1.rows));
Mat roiImg2 = img2(Rect(0,0,img2.cols,img2.rows));
roiImg1.copyTo(roiImgResult_Left); //Img1 will be on the left of imgResult
roiImg2.copyTo(roiImgResult_Right); //Img2 will be on the right of imgResult
Julien,
The easiest way I can think right now would be to create two windows instead of one. You can do it using cvNamedWindow(), and then position them side by side with cvMoveWindow().
After that if you now the position of the similarities on the images, you can draw your text near them. Take a look at cvInitFont(), cvPutText().