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  • Fastest possible way to render 480 x 320 background as iPhone OpenGL ES textures

    - by unknownthreat
    I need to display 480 x 320 background image in OpenGL ES. The thing is I experienced a bit of a slow down in iPhone when I use 512 x 512 texture size. So I am finding an optimum case for rendering iPhone resolution size background in OpenGL ES. How should I slice the background in this case to obtain the best possible performance? My main concern is speed. Should I go for 256 x 256 or other texture sizes here?

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  • Most efficient algorithm for mesh-level, optimal occlusion culling?

    - by Fredriku73
    I am new to culling. On a first glance, it seems that most occlusion culling algorithms are object-level, not examining single meshes, which would be practical for game rendering. What I am looking for is an algorithm that culls all meshes within a single object that are occluded for a given viewpoint, with high accuracy. It needs to be at least O(n log n), a naive mesh-by-mesh comparison (O(n^2)) is too slow. I notice that the Blender GUI identifies the occluded meshes for you in real-time, even if you work with large objects of 10,000+ meshes. What algorithm is used there, pray tell?

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  • Animation effect on C#

    - by Optimizer
    Can someone point me to a C# open source implementaion with a simple image animations. e.g. I feed the input image to animator, and the animation code produces a few dozen of images which if displayed sequentially looks like animation. I am not something extremely fancy - a simple DirectX filter like animations would do. Thank you.

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  • When should a uniform be used in shader programming?

    - by Phineas
    In a vertex shader, I calculate a vector using only uniforms. Therefore, the outcome of this calculation is the same for all instantiations of the vertex shader. Should I just do this calculation on the CPU and upload it as a uniform? What if I have ten such calculations? If I upload a lot of uniforms in this way, does CPU-GPU communication ever get so slow that recomputing such values in the vertex shader is actually faster?

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  • Simulating 3D 'cards' with just orthographic rendering

    - by meds
    I am rendering textured quads from an orthographic perspective and would like to simulate 'depth' by modifying UVs and the vertex positions of the quads four points (top left, top right, bottom left, bottom right). I've found if I make the top left and bottom right corners y position be the same I don't get a linear 'skew' but rather a warped one where the texture covering the top triangle (which makes up the quad) seems to get squashed while the bottom triangles texture looks normal. I can change UVs, any of the four points on the quad (but only in 2D space, it's orthographic projection anyway so 3D space won't matter much). So basically I'm trying to simulate perspective on a two dimensional quad in orthographic projection, any ideas? Is it even mathematically possible/feasible? ideally what I'd like is a situation where I can set an x/y rotation as well as a virtual z 'position' (which simulates z depth) through a function and see it internally calclate the positions/uvs to create the 3D effect. It seems like this should all be mathematical where a set of 2D transforms can be applied to each corner of the quad to simulate depth, I just don't know how to make it happen. I'd guess it requires trigonometry or something, I'm trying to crunch the math but not making much progress. here's what I mean: Top left is just the card, center is the card with a y rotation of X degrees and right most is a card with an x and y rotation of different degrees.

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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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  • 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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  • Alpha blending colors in .NET Compact Framwork 2.0

    - by Adam Haile
    In the Full .NET framework you can use the Color.FromArgb() method to create a new color with alpha blending, like this: Color blended = Color.FromArgb(alpha, color); or Color blended = Color.FromArgb(alpha, red, green , blue); However in the Compact Framework (2.0 specifically), neither of those prototypes are valid, you only get: Color.FromArgb(int red, int green, int blue); and Color.FromArgb(int val); The first one, obviously, doesn't even let you enter an alpha value, but the documentation for the latter shows that "val" is a 32bit ARGB value (as 0xAARRGGBB as opposed to the standard 24bit 0xRRGGBB), so it would make sense that you could just build the ARGB value and pass it to the function. I tried this with the following: private Color FromARGB(byte alpha, byte red, byte green, byte blue) { int val = (alpha << 24) | (red << 16) | (green << 8) | blue; return Color.FromArgb(val); } But no matter what I do, the alpha blending never works, the resulting color always as full opacity, even when setting the alpha value to 0. Has anyone gotten this to work on Compact Framework?

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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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  • Hanging Forms When I Drag And Move My Forms

    - by hosseinsinohe
    I Write a Windows Application By C Sharp. I Use a Picture in Background of my Form (MainForm) And I Use Many Picture in Buttons in This Form,And also I Use Some Panel And Label with Transparent Background Color. My Forms,Panels And Buttons has flicker. I solve this problem by a method in this thread. But Still when other Forms Start over this Form,my Forms hangs when I Drag and Move my Forms over this Form.How can I Solve this Problem to Move And Drags my Forms easily And Speed? Edit:: My Forms Load Data From Access 2007 DataBase file.I Use Datasets,DataGridViews And Other Components to Load And show Data in My Forms.

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  • How to draw/manage a hexagon grid?

    - by W.N.
    I've read this article: generating/creating hexagon grid in C . But look like both the author and answerer have already abandoned it. v(hexagonSide - hexagonWidth * hexagonWidth): What's hexagonSide and hexagonWidth? Isn't it will < 0 (so square root can't be calculated). And, can I put a hexagon into a rectangle? I need to create a grid like this: One more thing, how can I arrange my array to store data, as well as get which cells are next to one cell? I have never been taught about hexagon, so I know nothing about it, but I can easily learn new thing, so if you can explain or give me a clue, I may do it myself.

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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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  • 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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  • 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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  • 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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  • 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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  • 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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