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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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  • CALayer and Off-Screen Rendering

    - by Luke Mcneice
    I have a Paging UIScrollView with a contentSize large enough to hold a number of small UIScrollViews for zooming, The viewForZoomingInScrollView is a viewController that holds a CALayer for drawing a PDF page onto. This allows me to navigate through a PDF much like the ibooks PDF reader. The code that draws the PDF (Tiled Layers) is located in: - (void)drawLayer:(CALayer *)layer inContext:(CGContextRef)ctx; And simply adding a 'page' to the visible screen calls this method automatically. When I change page there is some delay before all the tiles are drawn, even though the object (page) has already been created. What i want to be able to do is render the next page before the user scrolls to it, thus preventing the visible tiling effect. However, i have found that if the layer is located offscreen adding it to the scrollview doesn't call the drawLayer. Any Ideas/common gotchas here? I have tried: [viewController.view.layer setNeedsLayout]; [viewController.view.layer setNeedsDisplay]; NB: The fact that this is replicating the ibooks functionally is irrelevant within the context of the full app.

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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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  • Asset tracking in "real-time" - how best to display in browser?

    - by mawg
    I am developing an asset tracking system, standard LAMP, and now am wondering how best to present the data to the user in the browser. I expect to track and most a few thousand items, and to refresh them every second or so. I want to draw a floorplan or map of the area and represent the assets the assets symbolically on that (with different symbols for different classes of assets). Additionally, the user should be able to click on an asset to interact with it, and search for a particular asset and centre the screen on it, draw a circle round it, etc http://graphite.wikidot.com/ Looks good - is there any alternative? At its simplest, I suppose I could just generate a JPEG and display it, using CSS to let me know if/where a user clicks ... but what's the "best" way to do it?

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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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  • Pango Cursor Rendering and Highlighting....

    - by user367255
    How do you render the cursor and create highlighting for selected text in Pango? Also, can I use PangoCairo to render parts of a layout at a time, so I can draw it in different ways (such as with an outline)? Finally, how did you get your understanding of Pango, there doesn't seem to be very many tutorials and the technical documentation only describes the functions. Thanks!

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  • How to handle alpha in a manual "Overlay" blend operation?

    - by quixoto
    I'm playing with some manual (walk-the-pixels) image processing, and I'm recreating the standard "overlay" blend. I'm looking at the "Photoshop math" macros here: http://www.nathanm.com/photoshop-blending-math/ (See also here for more readable version of Overlay) Both source images are in fairly standard RGBA (8 bits each) format, as is the destination. When both images are fully opaque (alpha is 1.0), the result is blended correctly as expected: But if my "blend" layer (the top image) has transparency in it, I'm a little flummoxed as to how to factor that alpha into the blending equation correctly. I expect it to work such that transparent pixels in the blend layer have no effect on the result, opaque pixels in the blend layer do the overlay blend as normal, and semitransparent blend layer pixels have some scaled effect on the result. Can someone explain to me the blend equations or the concept behind doing this? Bonus points if you can help me do it such that the resulting image has correctly premultiplied alpha (which only comes into play for pixels that are not opaque in both layers, I think.) Thanks! // factor in blendLayerA, (1-blendLayerA) somehow? resultR = ChannelBlend_Overlay(baseLayerR, blendLayerR); resultG = ChannelBlend_Overlay(baseLayerG, blendLayerG); resultB = ChannelBlend_Overlay(baseLayerB, blendLayerB); resultA = 1.0; // also, what should this be??

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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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  • 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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  • 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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  • 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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  • 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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  • 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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  • 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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  • 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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  • Resize PNG image

    - by serhiyiv
    HI! Could you please tell me how to resize a .png image. Or better give an example. I've been searching for the answer for a long time and it seems that nobody knows how to resize a .png image and keep its transparency. :(

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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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  • 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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  • On OSX, how do I gradient fill a path stroke?

    - by Emiel
    Using the plethora of drawing functions in Cocoa or Quartz it's rather easy to draw paths, and fill them using a gradient. I can't seem to find an acceptable way however, to 'stroke'-draw a path with a line width of a few pixels and fill this stroke using a gradient. How is this done?

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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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  • Draw 2.5D or 3D Map with C# from lines.

    - by VOX
    I'm developing a turn-by-turn navigation software for Windows Mobile using C# and .NET CF. I'm able to draw a 2D maps by drawing lines. My problem is I would like to get a 2.5D map like in the picture. I tried non-affine transformation on the 2D rendered image but it is too slow for the Windows Mobile device we are targeting. Could anyone give me a clue on my problem? example image

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