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  • Blind down animation on CALayer using a mask

    - by dgjones346
    Hi there, I want to create a "blind down" effect on an image so the image "blinds down" and appears. Sort of like this JavaScript transition: http://wiki.github.com/madrobby/scriptaculous/effect-blinddown The mask is setup correctly because if I manually change it's position it hides and reveals the image behind it, but it doesn't animate! It just ends up in the animates final position and you never see it actual blind. Please help! Maybe this isn't the best way to achieve a blind down effect? // create a new layer CALayer *numberLayer = [[CALayer alloc] init]; // render the number "7" on the layer UIImage *image = [UIImage imageNamed:@"number-7.png"]; numberLayer.contents = (id) [image CGImage]; numberLayer.bounds = CGRectMake(0, 0, image.size.width, image.size.height); // width and height are 50 numberLayer.position = position; // create a new mask that is 50x50 the size of the image CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init]; CGMutablePathRef path = CGPathCreateMutable(); CGPathAddRect(path, nil, CGRectMake(0, 0, 50, 50)); [maskLayer setPath:path]; [maskLayer setFillColor:[[UIColor whiteColor] CGColor]]; [theLayer setMask:maskLayer]; [maskLayer setPosition:CGPointMake(0, 0)]; // place the mask over the image [UIView beginAnimations:nil context:nil]; [UIView setAnimationDuration:3.0]; [maskLayer setPosition:CGPointMake(0, 50)]; // slide mask off the image // this should shift the blind away in an animation // but it doesn't animate [UIView commitAnimations]; [maskLayer release]; [boardLayer addSublayer:numberLayer]; [numberLayer release];

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  • CGContextDrawPDFPage taking up large amounts of memory

    - by Ed Marty
    I have a PDF file that I want to draw in outline form. I want to draw the first several pages on the document each in their own UIImage to use on a button so that when clicked, the main display will navigate to the clicked page. However, CGContextDrawPDFPage seems to be using copious amounts of memory when attempting to draw the page. Even though the image is only supposed to be around 100px tall, the application crashes while drawing one page in particular, which according to Instruments, allocates about 13 MB of memory just for the one page. Here's the code for drawing: //Note: This is always called in a background thread, but the autorelease pool is setup elsewhere + (void) drawPage:(CGPDFPageRef)m_page inRect:(CGRect)rect inContext:(CGContextRef) g { CGPDFBox box = kCGPDFMediaBox; CGAffineTransform t = CGPDFPageGetDrawingTransform(m_page, box, rect, 0,YES); CGRect pageRect = CGPDFPageGetBoxRect(m_page, box); //Start the drawing CGContextSaveGState(g); //Clip to our bounding box CGContextClipToRect(g, pageRect); //Now we have to flip the origin to top-left instead of bottom left //First: flip y-axix CGContextScaleCTM(g, 1, -1); //Second: move origin CGContextTranslateCTM(g, 0, -rect.size.height); //Now apply the transform to draw the page within the rect CGContextConcatCTM(g, t); //Finally, draw the page //The important bit. Commenting out the following line "fixes" the crashing issue. CGContextDrawPDFPage(g, m_page); CGContextRestoreGState(g); } Is there a better way to draw this image that doesn't take up huge amounts of memory?

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  • Android drawCircle's are not always 360 degrees

    - by user329999
    When I call drawCircle (ex. canvas.drawCircle(x, y, r, mPaint);) and I use Paint Style STROKE to initialize param #4 mPaint, the result doesn't quite make a full 360 degree (2*PI radian) circle in all cases. Sometimes you get a full circle (as I would expect) and sometimes only an arc. Does someone have an idea what would cause this to happen? I don't know what cases work and which don't (yet). I've noticed the ones that don't work seem to be the larger circles I'm drawing (100.0 radius). Could be size related. I am using floating point for x, y and r. I could try rounding to the nearest int when in the drawing code.

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  • Arc text in iphone application

    - by Amit Battan
    Hi all I want to bend the text that of UILabel from corner. It just like appear as arc or as following link. http://picasaweb.google.com/lh/photo/kfBzK4R4IlvyHfVywUNd1A?feat=directlink please suggest me, from where i start. any documentation,link, sample code. thanks amit battan

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  • Why the CLLocationManager delegate is not getting called in iPhone SDK 4.0 ???

    - by Biranchi
    Hi, This is the code that I have in my AppDelegate Class - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { CLLocationManager *locationManager = [[CLLocationManager alloc] init]; locationManager.delegate = self; locationManager.distanceFilter = 1000; // 1 Km locationManager.desiredAccuracy = kCLLocationAccuracyKilometer; [locationManager startUpdatingLocation]; } And this is the delegate method i have in my AppDelegate Class //This is the delegate method for CoreLocation - (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation { //printf("AppDelegate latitude %+.6f, longitude %+.6f\n", newLocation.coordinate.latitude, newLocation.coordinate.longitude); } Its working in 3.0, 3.1, 3.1.3 , but its not working in 4.0 simulator and device both. What is the reason ?? I am getting frustrated ...... Thanks....

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  • iPhone SDK Zoom and refresh PDF with Quartz

    - by Ben
    Looking at the QuartzDemo sample application, I love the speed of the PDF rending using quartz alone (that is, without using uiwebview). However, when I'm zooming in the PDF it doesn't seem to become more clear like it does in PDF view. Is there something that I can change to have the same effect when zooming in and out using multitouch? like manipulate the PDF transformation matrix or something? Thanks a bunch. --Ben

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  • Load CoreData objects' string property into UIPickerView

    - by OscarTheGrouch
    Hello Currently I have an entity named "Events" in a CoreData app. "Events" has one string property named "eventName". In the -(void)viewDidLoad I am trying to Fetch all the "Events" objects and load their "eventName" by alphabetical order into a UIPickerView. The ultimate end goal is through the use of a textField, buttons and the pickerView being add new objects in and remove unwanted objects out. Basically turning the UIPickerView into a UITableView. Currently I am able to save objects to the CoreData store, but am not able to pull them/their properties out into the UIPickerView. I am willing and able to share the project source code to anyone who wants it, or is willing to look at it to help out. thanks Chris

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  • Reasons for NSManagedObjectMergeError error on [NSManagedObjectContext save:]

    - by ross-kimes
    I have a application that combines threading and CoreData. I and using one global NSPersistentStoreCoordinator and a main NSManagedObjectContextModel. I have a process where I have to download 9 files simultaneously, so I created an object to handle the download (each individual download has its own object) and save it to the persistentStoreCoordinator. In the [NSURLConnection connectionDidFinishLoading:] method, I created a new NSManagedObject and attempt to save the data (which will also merge it with the main managedObjectContext). I think that it is failing due to multiple process trying to save to the persistentStoreCoordinator at the same time as the downloads are finishing around the same time. What is the easiest way to eliminate this error and still download the files independently? Thank you!

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  • iPhone Mapkit Blue Dot / User Location Region Zoom Question

    - by user290031
    Hey All, Is is possible to set a region based on a current location in a mapview only one time. I want my iphone app to get the current location, zoom into that current location, and then allow the user to scroll around. However, because my setRegion code is in my didUpdateToLocation function, every time the current location is updated, so is the region, and I can't scroll around on the map. I tried putting this setRegion code in the viewDidLoad function, but the user's current location isn't initialized at this point, so it doesn't work right. Any ideas?

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  • UIView using Quartz rendering engine to display PDF has poor quality compared to original.

    - by Josh Kerr
    I'm using the quartz rendering engine to display a PDF file on the iphone using the 3.0 SDK. The result is a bit blurry compared to a PDF being shown in a UIWebView. How can I improve the quality in the UIView so that I don't need to rewrite my app to use the UIWebView. I'm using pretty much close to the example code that Apple provides. Here is some of my sample code: CGContextRef gc = UIGraphicsGetCurrentContext(); CGContextSaveGState(gc); CGContextTranslateCTM(gc, 0.0, rect.size.height); CGContextScaleCTM(gc, 1.0, -1.0); CGAffineTransform m = CGPDFPageGetDrawingTransform(page, kCGPDFCropBox, rect, 0, false); CGContextConcatCTM(gc, m); CGContextSetGrayFillColor(gc, 1.0, 1.0); CGContextFillRect(gc, rect); CGContextDrawPDFPage(gc, page); CGContextRestoreGState(gc); Apple's tutorial code actually results in a blurry PDF view as well. If you drop the same PDF into a UIWebView you'll see it is actually sharper. Anyone have any ideas? This one issue is holding a two year development project from launching. :(

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  • CGBitmapContextCreate issue while trying to resize images

    - by Jeff
    Hello! I'm running into an issue when I try to create a CGContextRef while attempting to resize some images: There are the errors Sun May 16 20:07:18 new-host.home app [7406] <Error>: Unable to create bitmap delegate device Sun May 16 20:07:18 new-host.home app [7406] <Error>: createBitmapContext: failed to create delegate. My code looks like this - (UIImage*) resizeImage:(UIImage*)originalImage withSize:(CGSize)newSize { CGSize originalSize = originalImage.size; CGFloat originalAspectRatio = originalSize.width / originalSize.height; CGImageRef cgImage = nil; int bitmapWidth = newSize.width; int bitmapHeight = newSize.height; CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB(); CGContextRef context = CGBitmapContextCreate(nil, bitmapWidth, bitmapHeight, 8, bitmapWidth * 4, colorspace, kCGImageAlphaPremultipliedLast); if (context != nil) { // Flip the coordinate system //CGContextScaleCTM(context, 1.0, -1.0); //CGContextTranslateCTM(context, 0.0, -bitmapHeight); // Black background CGRect rect = CGRectMake(0, 0, bitmapWidth, bitmapHeight); CGContextSetRGBFillColor (context, 0, 0, 0, 1); CGContextFillRect (context, rect); // Resize box to maintain aspect ratio if (originalAspectRatio < 1.0) { rect.origin.y += (rect.size.height - rect.size.width / originalAspectRatio) * 0.5; rect.size.height = rect.size.width / originalAspectRatio; } else { rect.origin.x += (rect.size.width - rect.size.height * originalAspectRatio) * 0.5; rect.size.width = rect.size.height * originalAspectRatio; } CGContextSetInterpolationQuality(context, kCGInterpolationHigh); // Draw image CGContextDrawImage (context, rect, [originalImage CGImage]); // Get image cgImage = CGBitmapContextCreateImage (context); // Release context CGContextRelease(context); } CGColorSpaceRelease(colorspace); UIImage *result = [UIImage imageWithCGImage:cgImage]; CGImageRelease (cgImage); return result; }

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  • Simple iPhone drawing app with Quartz 2D

    - by Mr guy 4
    I am making a simple iPhone drawing program as a personal side-project. I capture touches event in a subclassed UIView and render the actual stuff to a seperate CGLayer. After each render, I call [self setNeedsLayout] and in the drawRect: method I draw the CGLayer to the screen context. This all works great and performs decently for drawing rectangles. However, I just want a simple "freehand" mode like a lot of other iPhone applications have. The way I thought to do this was to create a CGMutablePath, and simply: CGMutablePathRef path; -(void)touchBegan { path = CGMutablePathCreate(); } -(void)touchMoved { CGPathMoveToPoint(path,NULL,x,y); CGPathAddLineToPoint(path,NULL,x,y); } -(void)drawRect:(CGContextRef)context { CGContextBeginPath(context); CGContextAddPath(context,path); CGContextStrokePath(context); } However, after drawing for more than 1 second, performance degrades miserably. I would just draw each line into the off-screen CGLayer, if it were not for variable opacity! The less-than-100% opacity causes dots to be left on the screen connecting the lines. I have looked at CGContextSetBlendingMode() but alas I cannot find an answer. Can anyone point me in the right direction? Other iPhone apps are able to do this with very good efficiency.

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  • Expand and Shrink UIScrollView with animation

    - by Dilip Rajkumar
    I am having a UITableView inside a scrollview. So I am trying to do a accordion like component using UITableView. So I need to expand the UITableView to add more cell. In that case I have to increase the height of UIScrollView with a animation so that it matches the table animation. - (NSIndexPath *)tableView:(UITableView *)tableView willSelectRowAtIndexPath:(NSIndexPath *)indexPath { NSInteger row = [indexPath row]; BOOL preventReopen = NO; if (row == expandedRowIndex + 1 && expandedRowIndex != -1) return nil; [tableView beginUpdates]; if (expandedRowIndex != -1) { familyTableView.frame = CGRectMake(familyTableView.frame.origin.x, familyTableView.frame.origin.y, familyTableView.frame.size.width, 3*50+22); toolsTableView.frame = CGRectMake(toolsTableView.frame.origin.x, familyTableView.frame.origin.y + familyTableView.frame.size.height + 20, toolsTableView.frame.size.width, 4*50+22); myAccountTableView.frame = CGRectMake(myAccountTableView.frame.origin.x, toolsTableView.frame.origin.y + toolsTableView.frame.size.height + 20, myAccountTableView.frame.size.width, 2*50+22); settingsScrollView.contentSize = CGSizeMake(320, familyTableView.frame.size.height + toolsTableView.frame.size.height+ myAccountTableView.frame.size.height + 380); settingsScrollView.contentInset = UIEdgeInsetsMake(0, 0, familyTableView.frame.size.height + toolsTableView.frame.size.height+ myAccountTableView.frame.size.height + 380, 0); NSInteger rowToRemove = expandedRowIndex + 1; preventReopen = row == expandedRowIndex; if (row > expandedRowIndex) row--; expandedRowIndex = -1; [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:[NSIndexPath indexPathForRow:rowToRemove inSection:0]] withRowAnimation:UITableViewRowAnimationTop]; }else { familyTableView.frame = CGRectMake(familyTableView.frame.origin.x, familyTableView.frame.origin.y, familyTableView.frame.size.width, (3*50+22) + 100); toolsTableView.frame = CGRectMake(toolsTableView.frame.origin.x, familyTableView.frame.origin.y + familyTableView.frame.size.height + 20, toolsTableView.frame.size.width, 4*50+22); myAccountTableView.frame = CGRectMake(myAccountTableView.frame.origin.x, toolsTableView.frame.origin.y + toolsTableView.frame.size.height + 20, myAccountTableView.frame.size.width, 2*50+22); settingsScrollView.contentSize = CGSizeMake(320, familyTableView.frame.size.height + toolsTableView.frame.size.height+ myAccountTableView.frame.size.height + 380); settingsScrollView.contentInset = UIEdgeInsetsMake(0, 0, familyTableView.frame.size.height + toolsTableView.frame.size.height+ myAccountTableView.frame.size.height + 380, 0); } NSInteger rowToAdd = -1; if (!preventReopen) { rowToAdd = row + 1; expandedRowIndex = row; [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:[NSIndexPath indexPathForRow:rowToAdd inSection:0]] withRowAnimation:UITableViewRowAnimationTop]; } [tableView endUpdates]; return nil; } I am not good at animation. Any help is greatly appreciated. What I need is when we do [tableView beginUpdates] we have to start animating the resize effect to UIScrollView and it should end when [tableView endUpdates] executes. So the Accordion executes flawlessly. Thanks in advance for any help..

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  • CSG operations on implicit surfaces with marching cubes [SOLVED]

    - by Mads Elvheim
    I render isosurfaces with marching cubes, (or perhaps marching squares as this is 2D) and I want to do set operations like set difference, intersection and union. I thought this was easy to implement, by simply choosing between two vertex scalars from two different implicit surfaces, but it is not. For my initial testing, I tried with two spheres circles, and the set operation difference. i.e A - B. One circle is moving and the other one is stationary. Here's the approach I tried when picking vertex scalars and when classifying corner vertices as inside or outside. The code is written in C++. OpenGL is used for rendering, but that's not important. Normal rendering without any CSG operations does give the expected result. void march(const vec2& cmin, //min x and y for the grid cell const vec2& cmax, //max x and y for the grid cell std::vector<vec2>& tri, float iso, float (*cmp1)(const vec2&), //distance from stationary circle float (*cmp2)(const vec2&) //distance from moving circle ) { unsigned int squareindex = 0; float scalar[4]; vec2 verts[8]; /* initial setup of the grid cell */ verts[0] = vec2(cmax.x, cmax.y); verts[2] = vec2(cmin.x, cmax.y); verts[4] = vec2(cmin.x, cmin.y); verts[6] = vec2(cmax.x, cmin.y); float s1,s2; /********************************** ********For-loop of interest****** *******Set difference between **** *******two implicit surfaces****** **********************************/ for(int i=0,j=0; i<4; ++i, j+=2){ s1 = cmp1(verts[j]); s2 = cmp2(verts[j]); if((s1 < iso)){ //if inside circle1 if((s2 < iso)){ //if inside circle2 scalar[i] = s2; //then set the scalar to the moving circle } else { scalar[i] = s1; //only inside circle1 squareindex |= (1<<i); //mark as inside } } else { scalar[i] = s1; //inside neither circle } } if(squareindex == 0) return; /* Usual interpolation between edge points to compute the new intersection points */ verts[1] = mix(iso, verts[0], verts[2], scalar[0], scalar[1]); verts[3] = mix(iso, verts[2], verts[4], scalar[1], scalar[2]); verts[5] = mix(iso, verts[4], verts[6], scalar[2], scalar[3]); verts[7] = mix(iso, verts[6], verts[0], scalar[3], scalar[0]); for(int i=0; i<10; ++i){ //10 = maxmimum 3 triangles, + one end token int index = triTable[squareindex][i]; //look up our indices for triangulation if(index == -1) break; tri.push_back(verts[index]); } } This gives me weird jaggies: It looks like the CSG operation is done without interpolation. It just "discards" the whole triangle. Do I need to interpolate in some other way, or combine the vertex scalar values? I'd love some help with this. A full testcase can be downloaded HERE EDIT: Basically, my implementation of marching squares works fine. It is my scalar field which is broken, and I wonder what the correct way would look like. Preferably I'm looking for a general approach to implement the three set operations I discussed above, for the usual primitives (circle, rectangle/square, plane)

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  • Wrapping/warping a CALayer/UIView (or OpenGL) in 3D (iPhone)

    - by jbrennan
    I've got a UIView (and thus a CALayer) which I'm trying to warp or bend slightly in 3D space. That is, imagine my UIView is a flat label which I want to partially wrap around a beer bottle (not 360 degrees around, just on one "side"). I figured this would be possible by applying a transform to the view's layer, but as far as I can tell, this transform is limited to rotation, scale and translation of the layer uniformly. I could be wrong here, as my linear algebra is foggy at this point, to say the least. How can I achieve this?

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  • Rotating a UIButton with a custom image (animation)

    - by Tiago
    Hi, I'm trying to rotate a button that I've connected to the controller from the Interface Builder. I've set it's image right from Interface Builder. I'm using this code on the method that runs when I click it: [UIView beginAnimations:nil context:NULL]; [UIView setAnimationDuration:2.0]; [UIView setAnimationRepeatCount:5]; updateButton.transform = CGAffineTransformMakeRotation( M_PI ); [UIView commitAnimations]; But this doesn't do anything. Can this be done, or should I create the button programmatically in order to get it to rotate?

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  • Load NSImage into QPixmap or QImage

    - by Thomi
    I have an NSImage pointer from a platform SDK, and I need to load it into Qt's QImage class. To make things easier, I can create a QImage from a CGImageRef by using QPixmap as an intermediate format, like this: CGImageRef myImage = // ... get a CGImageRef somehow. QImage img = QPixmap::fromMacCGImageRef(myImage).toImage(); However, I cannot find a way to convert from an NSImage to a CGImageRef. Several other people have had the same problem, but I have yet to find a solution. There is the CGImageForProposedRect method, but I can't seem to get it to work. I'm currently trying this (img is my NSImage ptr): CGImageRef ir = [img CGImageFirProposedRect:0:0:0]; Any ideas?

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  • iPhone CoreData join

    - by Ken
    Hi guys, long time reader, first time poster. (A link to this schema is located here) http://www.weeshsoft.com/pix/DatabasePic.jpg I'm trying to get all LanguageEntries from a database for a given category.categoryName and languageset.languageSetName e.g. NSFetchRequest* fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"LanguageEntry" inManagedObjectContext:del.managedObjectContext]; [fetchRequest setEntity:entity]; NSString* predicateString = [NSString stringWithFormat:@"Category.categoryName = %@ AND LanguageSet.languageSetName = %@", @"Food", @"English####Spanish"]; fetchRequest.predicate = [NSPredicate predicateWithFormat:predicateString]; NSError *error = nil; NSArray* objects = [del.managedObjectContext executeFetchRequest:fetchRequest error:&error]; This always returns 0 objects. If I set the predicate string to match on one relationship (e.g. Category.categoryName = Food or languageSet.languageSetName = English####Spanish) it will return data. This is baffling, can anyone shed some light? -Ken

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  • Best way to learn iphone audio queue services, step by step tutorial

    - by optician
    Hi Everyone, I'm trying to learn how to handle audio at a fairly low level with audio queue services. I have been progrmaing in memory managed languages for quite a while, and have just completed the c programing tutorial by vtc (2007). This has left me comfortable with the understanding of pointers and memory allocation, but the apple documention still leaves me wanting for a simpler implenation and explaination. Maybe I need to learn objective c and cocoa better. I have heard that this book is good. Cocoa(R) Programming for Mac(R) OS X (3rd Edition) Could someone suggest a learning path that is going to help me get an better understanding of working with audio and an iphone. I want to be able to play mp3 files back and also alter the pitch of them as they are playing. I am prepared that I may have to temporarily convert the mp3 files into pcm files to do things like that to them. Thanks everyone.

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  • iPhone SDK: Rendering a CGLayer into an image object

    - by codemercenary
    Hi all, I am trying to add a curved border around an image downloaded and to be displayed in a UITableViewCell. In the large view (ie one image on the screen) I have the following: productImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:product.image]]; [productImageView setAlpha:0.4]; productImageView.frame = CGRectMake(10.0, 30.0, 128.0, 128.0); CALayer *roundedlayer = [productImageView layer]; [roundedlayer setMasksToBounds:YES]; [roundedlayer setCornerRadius:7.0]; [roundedlayer setBorderWidth:2.0]; [roundedlayer setBorderColor:[[UIColor darkGrayColor] CGColor]]; [self addSubview:productImageView]; In the table view cell, to get it to scroll fast, an image needs to be drawn in the drawRect method of a UIView which is then added to a custom cell. so in drawRect - (void)drawRect:(CGRect)rect { ... point = CGPointMake(boundsX + LEFT_COLUMN_OFFSET, UPPER_ROW_TOP); //CALayer *roundedlayer = [productImageView layer]; //[roundedlayer setMasksToBounds:YES]; //[roundedlayer setCornerRadius:7.0]; //[roundedlayer setBorderWidth:2.0]; //[roundedlayer setBorderColor:[[UIColor darkGrayColor] CGColor]]; //[productImageView drawRect:CGRectMake(boundsX + LEFT_COLUMN_OFFSET, UPPER_ROW_TOP, IMAGE_WIDTH, IMAGE_HEIGHT)]; // [productImageView.image drawInRect:CGRectMake(boundsX + LEFT_COLUMN_OFFSET, UPPER_ROW_TOP, IMAGE_WIDTH, IMAGE_HEIGHT)]; So this works well, but if I remove the comment and try to show the rounded CA layer the scrolling goes really slow. To fix this I suppose I would have to render this image context into a different image object, and store this in an array, then set this image as something like: productImageView.image = (UIImage*)[imageArray objectAtIndex:indexPath.row]; My question is "How do I render this layer into an image?" TIA.

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  • How do you draw like a Crayon?

    - by Simucal
    Crayon Physics Deluxe is a commercial game that came out recently. Watch the video on the main link to get an idea of what I'm talking about. It allows you to draw shapes and have them react with proper physics. The goal is to move a ball to a star across the screen using contraptions and shapes you build. While the game is basically a wrapper for the popular Box2D Physics Engine, it does have one feature that I'm curious about how it is implemented. Its drawing looks very much like a Crayon. You can see the texture of the crayon and as it draws it varies in thickness and darkness just like an actual crayon drawing would look like. The background texture is freely available here. Close up of crayon drawing - Note the varying darkness What kind of algorithm would be used to render those lines in a way that looks like a Crayon? Is it a simple texture applied with a random thickness and darkness or is there something more going on?

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  • Preload/predisplay tiles in a CATiledLayer?

    - by jemmons
    On the iPhone (though I imagine it's an equally valid question in Cocoa) I have a UIScrollView around a UIView backed by a CATiledLayer. The way it works by default is to load any uncached/unfetched tiles when my viewport scrolls over a blank section of the CATiledLayer. What I would like to know is if there's a way to trigger CATiledLayer to load a tile that's not actively being displayed? I would like to, for example, preload all tiles contiguous to the currently displayed tile while they are still offscreen, thus avoiding flashing a blank screen that fades in to the image once it's loaded asynchronously. Any ideas?

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  • JOGL Double Buffering

    - by Bar
    What is eligible way to implement double buffering in JOGL (Java OpenGL)? I am trying to do that by the following code: ... /** Creating canvas. */ GLCapabilities capabilities = new GLCapabilities(); capabilities.setDoubleBuffered(true); GLCanvas canvas = new GLCanvas(capabilities); ... /** Function display(…), which draws a white Rectangle on a black background. */ public void display(GLAutoDrawable drawable) { drawable.swapBuffers(); gl = drawable.getGL(); gl.glClear(GL.GL_COLOR_BUFFER_BIT | GL.GL_DEPTH_BUFFER_BIT); gl.glClearColor(0.0f, 0.0f, 0.0f, 0.0f); gl.glColor3f(1.0f, 1.0f, 1.0f); gl.glBegin(GL.GL_POLYGON); gl.glVertex2f(-0.5f, -0.5f); gl.glVertex2f(-0.5f, 0.5f); gl.glVertex2f(0.5f, 0.5f); gl.glVertex2f(0.5f, -0.5f); gl.glEnd(); } ... /** Other functions are empty. */ Questions: — When I'm resizing the window, I usually get flickering. As I see it, I have a mistake in my double buffering implementation. — I have doubt, where I must place function swapBuffers — before or after (as many sources says) the drawing? As you noticed, I use function swapBuffers (drawable.swapBuffers()) before drawing a rectangle. Otherwise, I'm getting a noise after resize. So what is an appropriate way to do that? Including or omitting the line capabilities.setDoubleBuffered(true) does not make any effect.

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