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  • How can I tell if a closed path contains a given point?

    - by Tom Seago
    In Android, I have a Path object which I happen to know defines a closed path, and I need to figure out if a given point is contained within the path. What I was hoping for was something along the lines of path.contains(int x, int y) but that doesn't seem to exist. The specific reason I'm looking for this is because I have a collection of shapes on screen defined as paths, and I want to figure out which one the user clicked on. If there is a better way to be approaching this such as using different UI elements rather than doing it "the hard way" myself, I'm open to suggestions. I'm open to writing an algorithm myself if I have to, but that means different research I guess.

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  • CGGradient Not Displaying Correctly on iPad 1 and 2

    - by daveMac
    I have been experimenting with creating my own gradients for the UI in my iOS app. I first used a CAGradientLayer but I was disappointed with the "stepped" look so I have been trying out CGGradient. enter code here I am having an issue with the Gradient displaying correctly. I have three iPads—one for each generation. The gradient looks right on the iPad 3 but not on the iPad 1 or 2. This is really strange. I was going to take a screenshot and post the two differences but even more strange, the screenshot look the same (and yes, the brightness is the same on both). The colors seem really washed out on the older iPads. I know the iPad 3 is a retina display, but I think it must be something more than that. Here is the code I am using: - (void)drawRect:(CGRect)rect { CGContextRef currentContext = UIGraphicsGetCurrentContext(); CGGradientRef skyGradient; CGColorSpaceRef rgbColorspace; size_t num_locations = 3; CGFloat locations[3] = { 0.0, .5, 1.0 }; CGFloat components[12] = { .106, .73, .93333, 1., 0.0, 0.0 , 1.0, 1., .106, .73, .93333, 1. }; rgbColorspace = CGColorSpaceCreateDeviceRGB(); skyGradient = CGGradientCreateWithColorComponents(rgbColorspace, components, locations, num_locations); CGRect currentBounds = self.bounds; CGPoint topLeft = CGPointMake(0.0f, 0.0f); CGPoint bottomRight = CGPointMake(CGRectGetMaxX(currentBounds), CGRectGetMaxY(currentBounds)); CGContextDrawLinearGradient(currentContext, skyGradient, topLeft, bottomRight, 0); CGGradientRelease(skyGradient); CGColorSpaceRelease(rgbColorspace); }

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  • Why I can't draw in a loop? (Using UIView in iPhone)

    - by Tattat
    I can draw many things using this : NSString *imagePath = [[NSBundle mainBundle] pathForResource:@"dummy2.png" ofType:nil]; UIImage *img = [UIImage imageWithContentsOfFile:imagePath]; image = CGImageRetain(img.CGImage); CGRect imageRect; double x = 0; double y = 0; for (int k=0; k<someValue; k++) { x += k; y += k; imageRect.origin = CGPointMake(x, y); imageRect.size = CGSizeMake(25, 25); CGContextDrawImage(UIGraphicsGetCurrentContext(), imageRect, image); } } CGImageRelease(img.CGImage); So, it works, so, I put it into a command object's execute method. Then, I want to do similar thing, but this time, my execute method only do this: NSString *imagePath = [[NSBundle mainBundle] pathForResource:@"dummy2.png" ofType:nil]; UIImage *img = [UIImage imageWithContentsOfFile:imagePath]; image = CGImageRetain(img.CGImage); CGRect imageRect; double x = inComingX; double y = inComingY; imageRect.origin = CGPointMake(x, y); imageRect.size = CGSizeMake(25, 25); CGContextDrawImage(UIGraphicsGetCurrentContext(), imageRect, image); CGImageRelease(img.CGImage); This time, this is also a Command, and it is the execute method. But I take the for loop away. I will have another method that pass the inComingX , and inComingY into my Command object. My Drawing method is simply execute the Cmd that passed in my drawingEngine: -(void)drawInContext:(CGContextRef)context { [self.cmdToBeExecuted execute]; } I also have the assign method to assign the command,: -(void)assignCmd:(Command* )cmd{ self.cmdToBeExecuted = cmd; } And this is the way I called the drawingEngine for(int k=0; k<5; k++){ [self.drawingEngine assignCmd:[DrawingCmd setDrawingInformation:(10*k):0:@"dummy.png"]]; [self.drawingEngine setNeedsDisplay]; } It can draw, but the sad thing is it only draw the last one. Why? and how to fix it? I can draw all the things in my First code, but after I take the loop outside, and use the loop in last code, it just only draw the last one. Plz help

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  • Finding the centroid of a polygon?

    - by user146780
    I have tried: for each vertex, add to total, divide by number of verities to get center. I'v also tried: Find the topmost, bottommost - get midpoint... find leftmost, rightmost, find midpoint. Both of these did not return the perfect center because I'm relying on the center to scale a polygon. I want to scale my polygons so I may put a border around them. What is the best way to find the centroid of a polygon given that the polygon may be concave, convex and have many many sides of various lengths. Thanks

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  • drawing arrows on a line defined by a set of points( for tracking)

    - by sirvan
    hi i have a set of point which define a route. and i must draw their so vehicle moving arrow denoted. this ponit may be form a curve... i want to draw arrows on the reout to define witch arrow vehicle goes, i have a mapviewr java applet and the last i must to do is this work, i want to define arrows on every 10 point on the rout a thing like this

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  • Is there a table of OpenGL extensions, versions, and hardware support somewhere?

    - by Thomas
    I'm looking for some resource that can help me decide what OpenGL version my game needs at minimum, and what features to support through extensions. Ideally, a table of the following format: 1.0 1.1 1.2 1.2.1 1.3 ... multitexture - ARB ARB core core texture_float - EXT EXT ARB ARB ... (Not sure about the values I put in, but you get the idea.) The extension specs themselves, at opengl.org, list the minimum OpenGL version they need, so that part is easy. However, many extensions have been accepted and became core standard in subsequent OpenGL versions, but it is very hard to find when that happened. The only way I could find is to compare the full OpenGL standards document for each version. On a related note, I would also very much like to know which extensions/features are supported by which hardware, to help me decide what features I can safely use in my game, and which ones I need to make optional. For example, a big honkin' table like this: MAX_TEXTURE_IMAGE_UNITS MAX_VERTEX_TEXTURE_IMAGE_UNITS ... GeForce 6xxx 8 4 GeForce 7xxx 16 8 ATi x300 8 4 ... (Again, I'm making the values up.) The table could list hardware limitations from glGet but also support for particular extensions, and limitations of such extension support (e.g. what floating-point texture formats are supported in hardware). Any pointers to these or similar resources would be hugely appreciated!

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  • Monochrome BitMap Library

    - by Asad Jibran Ahmed
    I am trying to create a piece of software that can be used to create VERY large (10000x10000) sized bitmaps. All I need is something that can work in monochrome, since the required output is a matrix containing details of black and white pixels in the bitmap. The closest thing I can think of is a font editor, but the size is a problem. Is there any library out there that I can use to create the software, or will I have to write the whole thing from the start?

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  • Which OpenGL functions are not GPU-accelerated?

    - by Xavier Ho
    I was shocked when I read this (from the OpenGL wiki): glTranslate, glRotate, glScale Are these hardware accelerated? No, there are no known GPUs that execute this. The driver computes the matrix on the CPU and uploads it to the GPU. All the other matrix operations are done on the CPU as well : glPushMatrix, glPopMatrix, glLoadIdentity, glFrustum, glOrtho. This is the reason why these functions are considered deprecated in GL 3.0. You should have your own math library, build your own matrix, upload your matrix to the shader. For a very, very long time I thought most of the OpenGL functions use the GPU to do computation. I'm not sure if this is a common misconception, but after a while of thinking, this makes sense. Old OpenGL functions (2.x and older) are really not suitable for real-world applications, due to too many state switches. This makes me realise that, possibly, many OpenGL functions do not use the GPU at all. So, the question is: Which OpenGL function calls don't use the GPU? I believe knowing the answer to the above question would help me become a better programmer with OpenGL. Please do share some of your insights.

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  • Resizing an image with alpha channel

    - by Hafthor
    I am writing some code to generate images - essentially I have a source image that is large and includes transparent regions. I use GDI+ to open that image and add additional objects. What I want to do next is to save this new image much smaller, so I used the Bitmap constructor that takes a source Image object and a height and width, then saved that. I was expecting the alpha channel to be smoothed like the color channels, but this did not happen -- it did result in a couple of semitransparent pixels, but overall it is very blocky. What gives? Using img As New Bitmap("source100x100.png") ''// Drawing stuff Using simg As New Bitmap(img, 20, 20) simg.Save("target20x20.png") End Using End Using Edit: I think what I want is SuperSampling, like what Paint.NET does when set to "Best Quality"

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  • RaphaelJS HTML5 Library pathIntersection() bug or alternative optimisation (screenshots)

    - by user1236048
    I have a chart generated using RaphaelJS library. It is just on long path: M 50 122 L 63.230769230769226 130 L 76.46153846153845 130 L 89.6923076923077 128 L 102.92307692307692 56 L 116.15384615384615 106 L 129.3846153846154 88 L 142.6153846153846 114 L 155.84615384615384 52 L 169.07692307692307 30 L 182.3076923076923 62 L 195.53846153846152 130 L 208.76923076923077 74 L 222 130 L 235.23076923076923 66 L 248.46153846153845 102 L 261.6923076923077 32 L 274.9230769230769 130 L 288.15384615384613 130 L 301.38461538461536 32 L 314.6153846153846 86 L 327.8461538461538 130 L 341.07692307692304 70 L 354.30769230769226 130 L 367.53846153846155 102 L 380.7692307692308 120 L 394 112 L 407.2307692307692 68 L 420.46153846153845 48 L 433.6923076923077 92 L 446.9230769230769 128 L 460.15384615384613 110 L 473.38461538461536 78 L 486.6153846153846 130 L 499.8461538461538 56 L 513.0769230769231 116 L 526.3076923076923 80 L 539.5384615384614 58 L 552.7692307692307 40 L 566 130 L 579.2307692307692 94 L 592.4615384615385 64 L 605.6923076923076 122 L 618.9230769230769 98 L 632.1538461538461 120 L 645.3846153846154 70 L 658.6153846153845 82 L 671.8461538461538 76 L 685.0769230769231 124 L 698.3076923076923 110 L 711.5384615384615 94 L 724.7692307692307 130 L 738 130 L 751.2307692307692 66 L 764.4615384615385 118 L 777.6923076923076 70 L 790.9230769230769 130 L 804.1538461538461 44 L 817.3846153846154 130 L 830.6153846153845 36 L 843.8461538461538 92 L 857.076923076923 130 L 870.3076923076923 76 L 883.5384615384614 130 L 896.7692307692307 60 L 910 88 Also below these chart I have a jqueryUI slider of the same width (860px) and centered with the chart. I want when I move the slider to move a dot on the chart accordingly with the slider position. See attached screenshot: As you can see it seems to work fine. I've implemented this behaviour using the pathIntersection() method. On the slide event at each ui.value (x coordinate) I intersect my chartPath (the one from above) with a vertical straight line at the x coordinate. But still there are some problems. One of them is that it runs very hard, and it kinda freezes sometimes.. and very weird sometimes it doesn't seem to intersect at all even it should.. I'll example below 2 cases I identified: M 499.8461538461538 0 L 499.8461538461538 140 M 910 0 L 910 140 Could you please explain why this intersect behaviour happens (it should return a dot).. and the worst part it seems like it happens randomly.. if I use another chartdata. Also if you can identify another (better) solution to syncronise the slider position with the dot on the chart.. would be perfect. I thought about using Element.getPointAtLength(length), but I don't know how. I think I should save the pathSegments and for each to compute the start Length and the finish Length.

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  • Blit Queue Optimization Algorithm

    - by martona
    I'm looking to implement a module that manages a blit queue. There's a single surface, and portions of this surface (bounded by rectangles) are copied to elsewhere within the surface: add_blt(rect src, point dst); There can be any number of operations posted, in order, to the queue. Eventually the user of the queue will stop posting blits, and ask for an optimal set of operations to actually perform on the surface. The task of the module is to ensure that no pixel is copied unnecessarily. This gets tricky because of overlaps of course. A blit could re-blit a previously copied pixel. Ideally blit operations would be subdivided in the optimization phase in such a way that every block goes to its final place with a single operation. It's tricky but not impossible to put this together. I'm just trying to not reinvent the wheel. I looked around on the 'net, and the only thing I found was the SDL_BlitPool Library which assumes that the source surface differs from the destination. It also does a lot of grunt work, seemingly unnecessarily: regions and similar building blocks are a given. I'm looking for something higher-level. Of course, I'm not going to look a gift horse in the mouth, and I also don't mind doing actual work... If someone can come forward with a basic idea that makes this problem seem less complex than it does right now, that'd be awesome too. EDIT: Thinking about aaronasterling's answer... could this work? Implement customized region handler code that can maintain metadata for every rectangle it contains. When the region handler splits up a rectangle, it will automatically associate the metadata of this rectangle with the resulting sub-rectangles. When the optimization run starts, create an empty region handled by the above customized code, call this the master region Iterate through the blt queue, and for every entry: Let srcrect be the source rectangle for the blt beng examined Get the intersection of srcrect and master region into temp region Remove temp region from master region, so master region no longer covers temp region Promote srcrect to a region (srcrgn) and subtract temp region from it Offset temp region and srcrgn with the vector of the current blt: their union will cover the destination area of the current blt Add to master region all rects in temp region, retaining the original source metadata (step one of adding the current blt to the master region) Add to master region all rects in srcrgn, adding the source information for the current blt (step two of adding the current blt to the master region) Optimize master region by checking if adjacent sub-rectangles that are merge candidates have the same metadata. Two sub-rectangles are merge candidates if (r1.x1 == r2.x1 && r1.x2 == r2.x2) | (r1.y1 == r2.y1 && r1.y2 == r2.y2). If yes, combine them. Enumerate master region's sub-rectangles. Every rectangle returned is an optimized blt operation destination. The associated metadata is the blt operation`s source.

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  • Merging photo textures - (from calibrated cameras) - projected onto geometry

    - by freakTheMighty
    I am looking for papers/algorithms for merging projected textures onto geometry. To be more specific, given a set of fully calibrated cameras/photographs and geometry, how can we define a metric for choosing which photograph should be used to texture a given patch of the geometry. I can think of a few attributes one may seek minimize including the angle between the surface normal and the camera, the distance of the camera from the surface, as well as minimizing some parameterization of sharpness. The question is how do these things get combined and are there well established existing solutions?

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  • C# Drawing Arc with 3 Points

    - by Keeper
    Hi, I need to draw an arc using GraphicsPath and having initial, median and final points. The arc has to pass on them. I tried .DrawCurve and .DrawBezier but the result isn't exactly an arc. What can I do?

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  • Displaying bitmaps in relative positions

    - by JonF
    I'd like to put a couple images on a surfaceview. I understand that the screen sizes of android devices can vary, so I don't think I can just use an x y position or I might end up placing it off different screens. Say I want to put two boxes in the center of the screen, a blue one and a red one. The blue one is to the left of the red one. How can I accomplish that while accounting for different screen sizes?

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  • Simple question about the lunarlander example.

    - by Smills
    I am basing my game off the lunarlander example. This is the run loop I am using (very similar to what is used in lunarlander). I am getting considerable performance issues associated with my drawing, even if I draw almost nothing. I noticed the below method. Why is the canvas being created and set to null each cycle? @Override public void run() { while (mRun) { Canvas c = null; try { c = mSurfaceHolder.lockCanvas();//null synchronized (mSurfaceHolder) { updatePhysics(); doDraw(c); } } finally { // do this in a finally so that if an exception is thrown // during the above, we don't leave the Surface in an // inconsistent state if (c != null) { mSurfaceHolder.unlockCanvasAndPost(c); } } } } Most of the times I have read anything about canvases it is more along the lines of: mField = new Bitmap(...dimensions...); Canvas c = new Canvas(mField); My question is: why is Google's example done that way (null canvas), what are the benefits of this, and is there a faster way to do it?

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  • Why are all my masked views unmasked in my view snapshot?

    - by mystify
    I'm taking a snapshot of an view. This view has got some subviews which have layer masks applied to them. For some reason, those masks take no effect in the snapshot and the masked parts are completely visible. UIGraphicsBeginImageContext(theView.frame.size); [theView.layer renderInContext:UIGraphicsGetCurrentContext()]; UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); I assume this is a bug in the framework. But maybe it's not? Did I do anything wrong here?

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