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  • Plotting an Arc in Discrete Steps

    - by phobos51594
    Good afternoon, Background My question relates to the plotting of an arbitrary arc in space using discrete steps. It is unique, however, in that I am not drawing to a canvas in the typical sense. The firmware I am designing is for a gcode interpreter for a CNC mill that will translate commands into stepper motor movements. Now, I have already found a similar question on this very site, but the methodology suggested (Bresenham's Algorithm) appears to be incompatable for moving an object in space, as it only relies on the calculation of one octant of a circle which is then mirrored about the remaining axes of symmetry. Furthermore, the prescribed method of calculation an arc between two arbitrary angles relies on trigonometry (I am implementing on a microcontroller and would like to avoid costly trig functions, if possible) and simply not taking the steps that are out of the range. Finally, the algorithm only is designed to work in one rotational direction (e.g. counterclockwise). Question So, on to the actual question: Does anyone know of a general-purpose algorithm that can be used to "draw" an arbitrary arc in discrete steps while still giving respect to angular direction (CW / CCW)? The final implementation will be done in C, but the language for the purpose of the question is irrelevant. Thank you in advance. References S.O post on drawing a simple circle using Bresenham's Algorithm: "Drawing" an arc in discrete x-y steps Wiki page describing Bresenham's Algorithm for a circle http://en.wikipedia.org/wiki/Midpoint_circle_algorithm Gcode instructions to be implemented (see. G2 and G3) http://linuxcnc.org/docs/html/gcode.html

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  • efficient android rendering

    - by llll
    I've read quite a few tutorials on game programming on android, and all of them provide basically the same solution as to drawing the game, that is having a dedicated thread spinning like this: public void run() { while(true) { if(!surfaceHolder.getSurface().isValid()) continue; Canvas canvas = surfaceHolder.lockCanvas(); drawGame(canvas); /* do actual drawing here */ surfaceHolder.unlockCanvasAndPost(canvas); } } now I'm wondering, isn't this wasteful? Suppose I've a game with very simple graphics, so that the actual time in drawGame is little; then I'm going to draw the same things on and on, stealing cpu from the other threads; a possibility could be skipping the drawing and sleeping a bit if the game state hasn't changed, which I could check by having the state update thread mantaining a suitable status flag. But maybe there are other options. For example, couldn'it be possible to synchronize with rendering, so that I don't post updates too often? Or am I missing something and that is precisely what lockCanvas does, that is it blocks and burns no cpu until proper time? Thanks in advance L.

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  • How would you update 100+ variables if something is changed in a different class?

    - by N. Lucas
    I have a class Grid which produces a graph paper like grid on in the drawing area. I then have 5 other classes for different shapes to draw with; Line, Polygon, Ellipse, Curve, Arc Now, these 5 classes use an instance of Grid because Grid has a resolution and a scale. Inside Grid I have: public function set resolution(x:Number):void { _gap = (modBy10(x) / 10); _scale = (modBy10(x) / (this.resolution * _scale)); draw(); } public function get resolution():Number { return (_gap * 10); } public function set scale(x:Number):void { _scale = (this.resolution / x); } public function get scale():Number { return _scale; } /**/ public function scaleLength(x:Number):Number { return (x * this.scale); } public function scaleLengthDown(x:Number):Number { return (x / this.scale); } public function scaleArea(x:Number):Number { return (x / Math.pow(this.scale, 2)); } I'm just lost for a solution on how to update every instance of my 5 drawing classes when Grid is changed. For instance, Polygon is made up of multiple instances of Line, Line(length, angle) where "length" is in either in, ft, cm, or m. If the user wishes to change the scale from say 10ft per 100px resolution.. Is there an easier way than re-drawing every Line inside Polygon?

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  • Drawing a dashed line across the tops of Flex Column Chart

    - by Anoop
    Hi all, Please find the below code <?xml version="1.0" encoding="utf-8"?> ]; ]]> This code is drawing a colum chart with two columns and drawing a line across the top of both columns. I have two requirements : the line need to be dashed as of now the line starts from top right corner of the first column to the same corner of the second column. How can i shift the line to the left, so that it starts from center of first column to center of second column. Regards, PK

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  • Freehand drawing with Quartz 2D

    - by qutaibah
    I am trying to develop a simple freehand-drawing app for red-marking some of my images. Below is a method that is called from within the drawRect. I want to ask if there is a way to avoid add the path every time the path is redrawn? Also, the way the draw method is set up, the drawing gets a bit slow and choopy after a few seconds. How can I improve the smoothness of the drawn path? thanks -(void)freehandDraw:(CGContextRef)context inRect:(CGRect)rect { CGPathAddLineToPoint( path, NULL, drawTip.x, drawTip.y); CGContextAddPath( context, path); CGContextStrokePath(context); } // method

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  • Android drawing cache

    - by Seva Alekseyev
    Please explain how does the drawing cache work in Android. I'm implementing a custom View subclass. I want my drawing to be cached by the system. In the View constructor, I call setDrawingCacheEnabled(true); Then in the draw(Canvas c), I do: Bitmap cac = getDrawingCache(); if(cac != null) { c.drawBitmap(cac, 0, 0, new Paint()); return; } Yet the getDrawingCache() returns null to me. My draw() is not called neither from setDrawingCacheEnabled(), nor from getDrawingCache(). Please, what am I doing wrong?

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  • Drawing the call stack in a recursive method

    - by Shaza
    Hey, I want to draw the call stack for any recursive method, so I've created a schema like this, recursiveMethod(){ //Break recursion condition if(){ // Add value here to the return values' list- No drawing return } else{ //Draw stack with the value which will be pushed to the stack here variable <- recursiveMethod() //Clear the drawing which represents the poped value from the stack here return variable }} Notes: This schema can draw recursive methods with n recursive call by making the recursive calls in a separate return statements. returnValues list, is a list which save all the return values, just for viewing issues. What do you think of this? any suggestions are extremely welcomed.

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  • Vertex Buffer Object not drawing in SDL window

    - by intregus
    I'm just using the opengl SDL template with Xcode, and everything runs fine. I removed the Atlantis code, and changed the main extension to .mm, then added some testing code to drawGL. Drawing a simple triangle (using immediate mode) at this point inside drawGL gives me a white triangle, but when I add the code to draw using a vertex buffer object, i just get a black window. Here is my VBO drawing code: glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Clear The Screen And The Depth Buffer glLoadIdentity(); GLuint buffer; float vertices[] = { 0.0f, 1.0f, 0.0f, -1.0f,-1.0f, 0.0f, 1.0f,-1.0f, 0.0f }; // VBO doesn't work :( glGenBuffers(1, &buffer); glBindBuffer(GL_ARRAY_BUFFER, buffer); glBufferData(GL_ARRAY_BUFFER, sizeof(float) * 9, vertices, GL_STATIC_DRAW); glEnableClientState(GL_VERTEX_ARRAY); glVertexPointer(3, GL_FLOAT, 0, vertices); glDrawArrays(GL_TRIANGLES, 0, 3); glDisableClientState(GL_VERTEX_ARRAY);

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  • Actionscript 3: foreach drawing object in movieclip

    - by Mathias
    Hey, I got a europe map designed in flash (1 movieclip, 1 frame, really simple), which contains the map as drawing objects directly inside the scene and in addition some specific countries as clickable buttons. So far it's working fine. What I need now is to make all the other drawing objects clickable without having to edit and script each object. I'm thinking about something like this (pseudo code): foreach(obj in MovieClip) { if(obj !typeof(Button)) { obj.addEventListener(MouseEvent.MOUSE_DOWN, genericClickListener); } } I just don't know the syntax how to achieve that. Could anybody give me a hint? Thanks, Mathias

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  • Problems with Linked List in C

    - by seePhor
    Hey everyone, I am new to C and I am working on an XOR linked list for a project. I have most of the code done, but I can't seem to get the delete function of the list to work properly. It seems able to delete some numbers, but not any number you pass into the function. Could anyone experienced with C take a look and possibly point out where I went wrong? I have been working on this for a while now and have not had much luck and I have started over 3 times :( Any help is much appreciated. Thank you. You can see my first attempt of code here. I can only post one link, so if you would like to see my second attempt, just tell me so and I can email it to you or something. Thank you for your time.

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  • Background Image w/Quartz Drawing

    - by James
    I'm using Quartz to do some basic drawing. I recently decided I wanted a background image for my app. So I went into my XIB file and added a UIImageView and set the background, looks good. However, when I run it, the Z-Index of the image is above my drawing. I googled a bit and found that you can do Layout Send to Back in IB...but that option is grayed out to me when I have my UIImageView selected. Is there an easy way to move this UIImageView permanently to the background? Is there perhaps an alternate method to doing this that I should consider? Thanks

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  • question about working with System.Drawing.Graphics

    - by backdoor
    hi all. i have a System.Drawing.Point[] filled with some System.Drawing.Point's. so when i want to draw this points as a polygon in a System.Windows.Form instance , the final drawn polygon is not all in the screen or sometimes is very small (in screen shown as 2-3 pixel). i wonder if there is some Library that using that i can just send Point[] to that and thatself scales and ... points and draws polygon manner that all points shown in screen and they are scaled to fit the screen (i mean small objects that shown as 2-3 pixel scale up to fit entire screen); thaks all and sorry for my bad english...

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  • How to effectively draw on desktop in C#?

    - by Lazlo
    I want to draw directly on the desktop in C#. From searching a bit, I ended up using a Graphics object from the Desktop HDC (null). Then, I painted normally using this Graphics object. The problem is that my shapes get lost when any part of the screen is redrawn. I tried a While loop, but it actually ends up drawing as fast as the application can, which is not the update rate of the desktop. Normally, I would need to put my drawing code in a "OnPaint" event, but such thing does not exist for the desktop. How would I do it? Example code: http://stackoverflow.com/questions/1536141/how-to-draw-directly-on-the-windows-desktop-c

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  • Path vs GeometryDrawing

    - by Carlo
    Just wondering what's lighter, I'm going to have a control that draws 280 * 4 my SegmentControl, which is a quarter of a circle, and I'm just wondering what's the way that takes least memory to draw said segment. GeometryDrawing: <Image> <Image.Source> <DrawingImage> <DrawingImage.Drawing> <GeometryDrawing Brush="LightBlue" Geometry="M24.612317,0.14044853 C24.612317,0.14044853 33.499971,-0.60608719 41,7.0179795 48.37642,14.516393 47.877537,23.404541 47.877537,23.404541 L24.60978,23.401991 z" /> </DrawingImage.Drawing> </DrawingImage> </Image.Source> </Image> Or Path: <Path Fill="LightBlue" Stretch="Fill" Stroke="#FF0DA17D" Data="M24.612317,0.14044853 C24.612317,0.14044853 33.499971,-0.60608719 41,7.0179795 48.37642,14.516393 47.877537,23.404541 47.877537,23.404541 L24.60978,23.401991 z" /> Or if you know of an even better way, it'll be much appreciated. Thanks!

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  • How to make sketching kind module in java?

    - by Nitz
    Hey Guys I am trying to make one software on which user can make any sketch and make any drawing kind of thing. i am trying to get reference from this two great software. 1. Notelab 2. Jarnal But both having great and many facility in it. But In my software i want only sketching-drawing, so how to do that? I tried to use Canvas but i don't get how to use it?

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  • DrawString only works in top-left part of form vb.net

    - by WillumMaguire
    Here is my code Public Class Form1 Public MyFormObject As Graphics = Me.CreateGraphics Public objFont = New System.Drawing.Font("arial", 20) Public a, b As Integer Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click Randomize() For i = 1 To 10 a = CInt(Int(Rnd() * Me.Width)) b = CInt(Int(Rnd() * Me.Height)) MyFormObject.DrawString("text", objFont, System.Drawing.Brushes.Black, a, b) Next End Sub End Class As you can see, I have one button that draws the string "text" randomly in the form 10 times. My problem is that it will ONLY draw the string in the upper-left portion of the form, roughly 260x260 starting at 0,0. It literally cuts off the text if it goes beyond. Why is this? Shouldn't it work for the entire form?

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  • How Can I: Generate 40/64 Bit WEP Key In Python?

    - by Aktariel
    So, I've been beating my head against the wall of this issue for several months now, partly because it's a side interest and partly because I suck at programming. I've searched and researched all across the web, but have not had any luck (except one small bit of success; see below), so I thought I might try asking the experts. What I am trying to do is, as the title suggests, generate a 40/64 bit WEP key from a passphrase, according to the "de facto" standard. (A site such as [http://www.powerdog.com/wepkey.cgi] produces the expected outputs.) I have already written portions of the script that take inputs and write them to a file; one of the inputs would be the passphrase, sanitized to lower case. For the longest time I had no idea what the defacto standard was, much less how to even go about implementing it. I finally stumbled across a paper (http://www.lava.net/~newsham/wlan/WEP_password_cracker.pdf) that sheds as much light as I've had yet on the issue (page 18 has the relevant bits). Apparently, the passphrase is "mapped to a 32-bit value with XOR," the result of which is then used as the seed for a "linear congruential PRNG (which one of the several PRNGs Python has would fit this description, I don't know), and then from that result several bits of the result are taken. I have no idea how to go about implementing this, since the description is rather vague. What I need is help in writing the generator in Python, and also in understanding how exactly the key is generated. I'm not much of a programmer, so explanations are appreciated as well. (Yes, I know that WEP isn't secure.)

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  • OpenGL bitmap text fails after drawing polygon

    - by kaykun
    I'm using Win32 and OpenGL to to draw text onto a window. I'm using the bitmap font method, with wglUseFontBitmaps. Here is my main rendering function: glClear(GL_COLOR_BUFFER_BIT); glPushMatrix(); glColor3f(1.0f, 0.0f, 1.0f); glBegin(GL_QUADS); glVertex2f(0.0f, 0.0f); glVertex2f(128.0f, 0.0f); glVertex2f(128.0f, 128.0f); glVertex2f(0.0f, 128.0f); glEnd(); glPopMatrix(); glPushMatrix(); glColor3f(1.0f, 1.0f, 1.0f); glRasterPos2i(200, 200); glListBase(fontList); glCallLists(5, GL_UNSIGNED_BYTE, "Test."); glPopMatrix(); SwapBuffers(hDC); As you can see it's very simple and the only thing that it's supposed to do is draw a quadrilateral and draw the text "Test.". But the problem is that drawing a polygon seems to mess up any text operations I try to do after it. If I place the text drawing functions before the polygon, both the text and the polygon draw fine. Is there something I'm missing here? Edit: This problem only happens when the window is run in Fullscreen, by ChangeDisplaySettings. Any reason why this would be??

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  • OpenGL bitmap text fails after drawing polygon

    - by kaykun
    Hi, I'm using Win32 and OpenGL to to draw text onto a window. I'm using the bitmap font method, with wglUseFontBitmaps. Here is my main rendering function: glClear(GL_COLOR_BUFFER_BIT); glPushMatrix(); glColor3f(1.0f, 0.0f, 1.0f); glBegin(GL_QUADS); glVertex2f(0.0f, 0.0f); glVertex2f(128.0f, 0.0f); glVertex2f(128.0f, 128.0f); glVertex2f(0.0f, 128.0f); glEnd(); glPopMatrix(); glPushMatrix(); glColor3f(1.0f, 1.0f, 1.0f); glRasterPos2i(200, 200); glListBase(fontList); glCallLists(5, GL_UNSIGNED_BYTE, "Test."); glPopMatrix(); SwapBuffers(hDC); As you can see it's very simple and the only thing that it's supposed to do is draw a quadrilateral and draw the text "Test.". But the problem is that drawing a polygon seems to mess up any text operations I try to do after it. If I place the text drawing functions before the polygon, both the text and the polygon draw fine. Is there something I'm missing here? Any help is appreciated.

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  • Drawing a relative line in C#

    - by icemanind
    Guys, I know this is going to turn out to be a simple answer, but I can't seem to figure it out. I have a C# Winform application that I am trying to build. I am trying to draw a white line 60 pixels above the bottom of the form. I am using this code: private void MainForm_Paint(object sender, PaintEventArgs e) { e.Graphics.DrawLine(Pens.White, 10, this.Height-60, 505, this.Height-60); } Simple enough, however no line is drawn. After some debugging, I figured out that it IS drawing the line, but it is drawing it outside my form. If I change the -60 to -175, then I can see it at the bottom of my form. This would solve my problem, except as my form's height changes, the line draws closer and closer to the bottom of my form until eventually, its off the form again. What am I doing wrong? Am I using the wrong graphics unit? Or is there a more complex calculation I need to do to determine 60 pixels from the bottom of my form?

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  • Drawing an image is completely out

    - by ct2k7
    Hi I'm using this code below to let a user "draw" their signature on a UIView component on my app: UIGraphicsBeginImageContext(signature.frame.size); [drawImage.image drawInRect:CGRectMake(0, 0, signature.frame.size.width, signature.frame.size.height)]; CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound); CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0); CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0); CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y); CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y); CGContextStrokePath(UIGraphicsGetCurrentContext()); CGContextFlush(UIGraphicsGetCurrentContext()); drawImage.image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext() The issue I am having is that the drawing is not only is the drawing not in line with the pointer when in use in the simulator, the image is going outside of the designated UIView compontent and is getting smaller/out of focus the more I draw, as you can see in this image: And after a few lines, showing the boundaries of the exact are of where I can draw: Any ideas on what's happening here? lastPoint.y is defined as: lastPoint.y -= 20; Any ideas on what on earth is happening here?

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  • Drawing graphics on top of a JButton

    - by trinth
    I have a situation wherein I have a bunch of JButtons on a GridLayout. I need each of the JButtons to have: a background image (but retain the ability to keep the default button look if needed) custom graphics drawn on top by other classes I have no trouble with the background image, since I am using setIcon() but I am having problems drawing things on top of the background. At one point I was able to draw on top of the button, but after the button was clicked, the drawings disappeared. How can make the button keep this drawing state? Basically, I need a way for my JButtons to have public methods that would allow another class to draw anything on it such as: public void drawSomething() { Graphics g = this.getGraphics(); g.drawOval(3,2,2,2); repaint(); } or public Graphics getGraphics() { return this.getGraphics(); } then another class could do this: button.getGraphics().drawSomething(); The latter is more what I am looking for but the first is equally useful. Is there any way to go about this? Also, overriding the parent class method paintComponent() doesn't help since I need each button to have different graphics.

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  • Box2D in Flash runs quicker when drawing debug data than not

    - by bowdengm
    I've created a small game with Box2d for AS3 - I have sprites attached to the stage that take their position from the underlying Box2d world. These sprites are mostly PNGs. When the game runs with DrawDebugData() bening called every update, it runs nice and smoothly. However when I comment this out, it runs choppily. In both cases all my sprites are being rendered. So it seems that it's running faster when it's drawing the debug data additionaly (i.e. my sprites are on the screen in both cases!) What's going on? Does drawing the debug data flick some sort of 'render quick' switch? If so, what's the switch!? I can't see it in the Box2D code. function Update(e){ m_world.Step(m_timeStep, m_velocityIterations, m_positionIterations); // draw debug? m_world.DrawDebugData(); // with the above line in, I get 27fps, without it, I get 19fps. // that's the only change that's causing such a huge difference. doStuff(); } Interestingly, If i set the debug draw scale to something different to my world scale, it slows down to 19fps. So there's something happening when it draws the boxes under my sprites causing it to run quicker.. Cheers, Guy

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