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  • Optimal pixel format for drawing on iPhone?

    - by Felixyz
    Pretty simple question: when doing some pretty intense drawing with CoreGraphics on the iPhone, how can I specify the pixel format to get optimal performance? Is the format that I get from the context via UIGraphicsGetCurrentContext per definition the best one? I know that RGB565 is supposed to be the fastest to use in OpenGL. Does that go for CoreGraphics as well? General advice?

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  • How to generate irregular ball shapes?

    - by tomato
    What kind of algorithms would generate random "goo balls" like those in World of Goo. (btw, if you haven't played it yet, highly recommended). I'm using Proccesing, but any generic algorithm would do. I guess it boils down to how to "randomly" make balls that are kind of round, but not perfectly round, and still looking realistic. Thanks in advance!

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  • Sorting a list of colors in one dimension?

    - by Ptah- Opener of the Mouth
    I would like to sort a one-dimensional list of colors so that colors that a typical human would perceive as "like" each other are near each other. Obviously this is a difficult or perhaps impossible problem to get "perfectly", since colors are typically described with three dimensions, but that doesn't mean that there aren't some sorting methods that look obviously more natural than others. For example, sorting by RGB doesn't work very well, as it will sort in the following order, for example: (1) R=254 G=0 B=0 (2) R=254 G=255 B=0 (3) R=255 G=0 B=0 (4) R=255 G=255 B=0 That is, it will alternate those colors red, yellow, red, yellow, with the two "reds" being essentially imperceivably different than each other, and the two yellows also being imperceivably different from each other. But sorting by HLS works much better, generally speaking, and I think HSL even better than that; with either, the reds will be next to each other, and the yellows will be next to each other. But HLS/HSL has some problems, too; things that people would perceive as "black" could be split far apart from each other, as could things that people would perceive as "white". Again, I understand that I pretty much have to accept that there will be some splits like this; I'm just wondering if anyone has found a better way than HLS/HSL. And I'm aware that "better" is somewhat arbitrary; I mean "more natural to a typical human". For example, a vague thought I've had, but have not yet tried, is perhaps "L is the most important thing if it is very high or very low", but otherwise it is the least important. Has anyone tried this? Has it worked well? What specifically did you decide "very low" and "very high" meant? And so on. Or has anyone found anything else that would improve upon HSL? I should also note that I am aware that I can define a space-filling curve through the cube of colors, and order them one-dimensionally as they would be encountered while travelling along that curve. That would eliminate perceived discontinuities. However, it's not really what I want; I want decent overall large-scale groupings more than I want perfect small-scale groupings. Thanks in advance for any help.

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  • What is the best approach to 2D collision detection on the iPhone?

    - by Magic Bullet Dave
    Been working on this problem of collision detection and there appears to be 3 main approaches I could take: Sprite and mask approach. (AND the overlap of the sprites and check for a non-zero number in the resulting sprite pixel data). Bounding circles, rectangles or polygons. (Create one or more shapes that enclose the sprites and do the basic maths to check for overlaps). Use an existing sprite library. The first approach, even though it would have been the way I would have done it in the old days of 16x16 sprite blocks, it appears that there just isn’t an easy way of getting at the individual image pixel data and/or alpha channel within Quartz (or OPENGL for that matter). Detecting the overlap of the bounding box is easy, but then creating a 3rd image from the overlap and then testing it for pixels is complicated and my gut feel is that even if we could get it to work would be slow. Am I missing something neat here? The second approach involves dividing up our sprites into several polygons and testing them for overlaps. The more polygons the more accurate the collision detection. The benefit is that it is fast, and can be accurate. The downside is it makes the sprite creation more complicated. i.e., we have to create the polygons for each sprite. For speed the best approach is to create a tree of polygons. The 3rd approach I’m not sure about as it involves buying code (or using an open source licence). I am not sure what the best library to use is or whether this would make life easier or give us a problem integrating this into our app. So in short I am favouring the polygon and tree approach and would appreciate you views on this before I go and write lots of code. Best regards Dave

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  • extracting a quadrilateral image to a rectangle

    - by Will
    In the image below, the sign on the side of the van is not face-on to the camera. I want to calculate, as best I can with the pixels I have, what it'd look like face on. I imagine that this is some kind of loop through the x and y axis doing a Bresenham's line on both dimensions at once with some kind of mixing when pixels in the source image overlap - some sub-pixel mixing of some sort? What approaches are there, and how do you mix the pixels? Is there a standard approach for this?

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  • How i access the array of CGPoints to draw the graph?

    - by Rajendra Bhole
    Hi, I have the code in which i want to develop the graph.The code is, NSArray *coordinate = [[NSArray alloc] initWithObjects: @"42,213", @"75,173", @"108,153", @"141,133", @"174,113", @"207,73", @"240,33", nil]; CGContextSetRGBFillColor(ctx, 255, 0, 0, 1.0); CGContextSetLineWidth(ctx, 8.0); for(int intIndex = 0; intIndex < [coordinate count]; fltX1+=33, intIndex++) { CGContextMoveToPoint(ctx, fltX1+37, fltY2+18); CGPoint point = [[coordinate objectAtIndex:intIndex] CGPointValue]; CGContextAddLineToPoint(ctx, point); CGContextStrokePath(ctx); } The problem is that the function of CGContextAddLineToPoint(ctx, point); not working properly. How i drawing the line in the graph using above code????????

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  • Projective transformation

    - by mcwehner
    Given two image buffers (assume it's an array of ints of size width * height, with each element a color value), how can I map an area defined by a quadrilateral from one image buffer into the other (always square) image buffer? I'm led to understand this is called "projective transformation". I'm also looking for a general (not language- or library-specific) way of doing this, such that it could be reasonably applied in any language without relying on "magic function X that does all the work for me". An example: I've written a short program in Java using the Processing library (processing.org) that captures video from a camera. During an initial "calibrating" step, the captured video is output directly into a window. The user then clicks on four points to define an area of the video that will be transformed, then mapped into the square window during subsequent operation of the program. If the user were to click on the four points defining the corners of a door visible at an angle in the camera's output, then this transformation would cause the subsequent video to map the transformed image of the door to the entire area of the window, albeit somewhat distorted.

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  • OpenGL: How to draw Bezier curve of degree higher then 8?

    - by maciekp
    I am trying to draw high order Bezier Curve using OpenGL evaluators: glMap1f(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, 30, &points[0][0]); glMapGrid1f(30, 0, 1); glEvalMesh1(GL_LINE, 0, 30); or glBegin(GL_LINE_STRIP); for (int i = 0; i <= 30; i++) glEvalCoord1f((GLfloat) i/30.0); glEnd(); When number of points exceeds 8, curve disappears. How to draw higher order Bezier curve using evaluators?

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  • R: ca plotting text attributes

    - by chasec
    Does anyone know of a way to control the font size/color/weight of the row and column names when plotting a correspondence plot with the ca package? The following code will produce a very nice looking chart, though if there were more attributes (very heavy, super heavy, something more than super heavy) or more classes of workers (peons, underlings, etc) then the graph will get a little cluttered and hard to tell what was what. It would be nice if you could list all the attributes in a separate color than the categories of workers. library(ca) data("smoke") plot(ca(smoke) , map = "symmetric" , what =c("active","active") , mass = c(T,T) , contrib = "absolute" , col = c("red","blue") , pch = c(15,17,15,17) , labels = c(2,2) , arrows = c(T,F) ) Alternatively, does anyone know if there is a way to reproduce something along these lines with ggplot2? I didn't find anything on the website that seemed comparable, but I don't know much about the package. Thanks, -Chase

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  • How does Content-Aware fill work?

    - by CiscoIPPhone
    The upcoming version of Photoshop a feature called Content-Aware fill. This feature will fill a selection of an image based on the surrounding image - to the point it can generate bushes and clouds while being seamless with the surrounding image. See http://www.youtube.com/watch?v=NH0aEp1oDOI for a preview of the Photoshop feature I'm talking about. My question is: How does this feature work algorithmically?

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  • Convert text box text into Argb argument

    - by Jimmy
    I have been looking into coloring objects like ellipses with code such as SolidBrush trnsRedBrush = new SolidBrush(Color.FromArgb(0x78FF0000)); I'd like to play around further with this by entering FromArgb's argument into a textbox on a form, then using the textbox to set the Brush's color. How would I convert the textbox's text into an argument usable by FromArgb?

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  • VB6 Game Development

    - by CVS-2600Hertz-wordpress-com
    Hi All, I am developing a game in VB6 (plz don't ask me why :) ). The storyboard is ready and a rough implementation is underway. I am following a "pure-software-rendering" approach. (i.e. no DirectX, no openGL etc.) Amongst many others, the following "serious" problems exist: 2D alpha transparency reqd. to implement overlays. Parallax implementation to give depth-of-field illusion. Capturing mouse-scroll events globally (as in FPS-es; mapping them to changing weapon). Async sound play with absolute "near-zero-lag". Any ideas anyone. Please suggest any well documented library/ocx or sample-code. Plz do suggest solutions with good performance and as little overhead as possible. Also, anyone who has developed any games, and would be open to sharing her/his code would be highly appreciated. (any well-acknowledged VB games whose source-code i can study??) UPDATE: Here is a screen shot of GearHead Garage. This picture ought to describe what i was attempting in words above... :) Thank You

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  • Is PyOpenGL a good place to start learning opengl programing?

    - by Isaiah
    I want to start learning OpenGL but I don't really want to have to learn another language to do it. I already am pretty proficient in python and enjoy the language. I just want to know how close it is to the regular api? Will I be able to pretty easily follow tutorials and books without too much trouble? I know C++ gives better performance, but for just learning can I go wrong with PyOpenGL? Thanks alot

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  • How do I visualize a complex graph in .Net?

    - by Ivan
    I need to visualize a graph (technically being a set of Entity Framework objects, but I can translate it to another representation if needed) of this kind. I don't know how to name it (by the way, if you know - I'll appreciate if you tell me). It would be ideal for graph elements to be clickable (so that when user clicks on a block, I can handle an event with the element id specified) but I can survive even without any interactivity. Are there any components available good for this task? If no, what should I look for to help me to develop an algorithm for drawing such a graph with visually-comfortable layout?

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  • Different cursor formats in IOFrameBufferShared

    - by Thomi
    Hi, I'm reading the moust cursor pixmap data from the StdFBShmem_t structure, as defined in the IOFrameBufferShared API. Everything works fine, 90% of the time. However, I have noticed that some applications on the mac set a cursor in a different format. According to the documentation for the data structures, the cursor pixmap format should always be in the same format as the frame buffer. My frame buffer is 32BPP. I expect the pixmap data to be in the format 0xAARRGGBB, which is it. However, in some cases, I'm reading data that looks like a mask. Specifically, the pixel will either be 0x00FFFFFF or `0x00000000. This looks to me to be a mask for separate pixel data stored somewhere else. As far as I can tell, the only application that uses this cursor pixel format is Qt Creator, but I need to work with all applications, so I'd like to sort this out. The code I'm using to read the cursor pixmap data is: NSAutoreleasePool *autoReleasePool = [[NSAutoreleasePool alloc] init]; NSPoint mouseLocation = [NSEvent mouseLocation]; NSArray *allScreens = [NSScreen screens]; NSEnumerator *screensEnum = [allScreens objectEnumerator]; NSScreen *screen; NSDictionary *screenDesc = nil; while ((screen = [screensEnum nextObject])) { NSRect screenFrame = [screen frame]; screenDesc = [screen deviceDescription]; if (NSMouseInRect(mouseLocation, screenFrame, NO)) break; } if (screen) { kern_return_t err; CGDirectDisplayID displayID = (CGDirectDisplayID) [[screenDesc objectForKey:@"NSScreenNumber"] pointerValue]; task_port_t taskPort = mach_task_self(); io_service_t displayServicePort = CGDisplayIOServicePort(displayID); io_connect_t displayConnection =0; err = IOFramebufferOpen(displayServicePort, taskPort, kIOFBSharedConnectType, &displayConnection); if (KERN_SUCCESS == err) { union { vm_address_t vm_ptr; StdFBShmem_t *fbshmem; } cursorInfo; vm_size_t size; err = IOConnectMapMemory(displayConnection, kIOFBCursorMemory, taskPort, &cursorInfo.vm_ptr, &size, kIOMapAnywhere | kIOMapDefaultCache | kIOMapReadOnly); if (KERN_SUCCESS == err) { // for some reason, cursor data is not always in the same format as the frame buffer. For this reason, we need // some way to detect which structure we should be reading. QByteArray pixData((const char*)cursorInfo.fbshmem->cursor.rgb24.image[currentFrame], m_mouseInfo.currentSize.width() * m_mouseInfo.currentSize.height() * 4); IOConnectUnmapMemory(displayConnection, kIOFBCursorMemory, taskPort, cursorInfo.vm_ptr); } // IOConnectMapMemory else qDebug() << "IOConnectMapMemory Failed:" << err; IOServiceClose(displayConnection); } // IOServiceOpen else qDebug() << "IOFramebufferOpen Failed:" << err; }// if screen [autoReleasePool release]; My question is: How can I detect if the cursor is a different format from the framebuffer? Where can I read the actual pixel data? the bm18Cursor structure contains a mask section, but it's not in the right place for me to be reading it using the code above. Cheers,

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  • Generate 2D cross-section polygon from 3D mesh

    - by nornagon
    I'm writing a game which uses 3D models to draw a scene (top-down orthographic projection), but a 2D physics engine to calculate response to collisions, etc. I have a few 3D assets for which I'd like to be able to automatically generate a hitbox by 'slicing' the 3D mesh with the X-Y plane and creating a polygon from the resultant edges. Google is failing me on this one (and not much helpful material on SO either). Suggestions?

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  • Simple 3D Editor/Viewer

    - by mnn
    I'm looking for an application, which could be able to load bunch of points in space, render them and be able to simple 3D operations (select such point, rotate & move viewport). The source has to be available, as I want to use it as basis for my own application.

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  • Image Transformation on iPhone, how to?

    - by Horace Ho
    Since I cannot pre-render all the images in PNGs and real-time image transformation functions are required, namely: skew perspective (like the transform action found in Photoshop) Which API (CoreAnimation? OpenGL ES?) should I look into? Even better, is there any sample code around? Thanks!

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  • Spinning a 3D model in C#

    - by icemanind
    How do I take a 3D model that I created in 3D Studio Max and put it into my Winform C# program and make it spin? I'd prefer not to use DirectX if possible. I don't want anything complex. I simply want my model to rotate along the X axis. Thats it. Thanks

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  • minimum enclosing rectangle of fixed aspect ratio

    - by Ramya Narasimha
    I have an Image with many rectangles at different positions in the image and of different sizes (both overlapping and non-overlapping). I also have a non-negative scores associated with each of these rectangles. My problem now is to find one larger rectangle *of a fixed (given) aspect ratio* that encloses as many of these rectangles as possible. I am looking for an algorithm to do this, if anyone has a solution, even a partial one it would be helpful. Please note that the positions of the rectangles in the image is fixed and cannot be moved around and there is no orientation issue as all of them are upright.

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  • How does a GUI Framework work?

    - by AlexW.H.B.
    I have been all over the web looking for an answer to this, and my question is this: How does a GUI framework work? for instance how does Qt work, is there any books or wibsites on the topic of writing a GUI framework from scratch? and also does the framework have to call methods from the operating systems GUI framework? -- Thank you to any one who takes the time to try to answer this question, and forgive me if i misspelled anything.

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