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  • algorithm to make easy my job

    - by gcc
    Iwill tell part of study material task but, dont afraid, I dont want write all of them , I will ask just specific question.okey; User will give me a function with three unknown. example: sin(a+b)+ln(5)*(log(ab)-32/sqrt(abc)) another example for function atan(23/a)-exp(a,b)*(123+asin(ac)) and there are some another input with funtion but in all input a,b and c, are doesnot determined, Anyway,I wont tell the other part,I just asking how I should take the fuction such that I can do my job with easy?

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  • Thread too slow. Better way to execute code (Android AndEngine)?

    - by rphello101
    I'm developing a game where the user creates sprites with every touch. I then have a thread run to check to see if those sprites collide with any others. The problem is, if I tap too quickly, I cause a null pointer exception error. I believe it's because I'm tapping faster than my thread is running. This is the thread I have: public class grow implements Runnable{ public grow(Sprite sprite){ } @Override public void run() { float radf, rads; //fill radius/stationary radius float fx=0, fy=0, sx, sy; while(down){ if(spriteC[spriteNum].active){ spriteC[spriteNum].sprite.setScale(spriteC[spriteNum].scale += 0.001); if(spriteC[spriteNum].sprite.collidesWith(ground)||spriteC[spriteNum].sprite.collidesWith(roof)|| spriteC[spriteNum].sprite.collidesWith(left)||spriteC[spriteNum].sprite.collidesWith(right)){ down = false; spriteC[spriteNum].active=false; yourScene.unregisterTouchArea(spriteC[spriteNum].sprite); } fx = spriteC[spriteNum].sprite.getX(); fy = spriteC[spriteNum].sprite.getY(); radf=spriteC[spriteNum].sprite.getHeightScaled()/2; Log.e("F"+Float.toString(fx),Float.toString(fy)); if(spriteNum>0) for(int x=0;x<spriteNum;x++){ rads=spriteC[x].sprite.getHeightScaled()/2; sx = spriteC[x].body.getWorldCenter().x * 32; sy = spriteC[x].body.getWorldCenter().y * 32; Log.e("S"+Float.toString(sx),Float.toString(sy)); Log.e(Float.toString((float) Math.sqrt(Math.pow((fx-sx),2)+Math.pow((fy-sy),2))),Float.toString((radf+rads))); if(Math.sqrt(Math.pow((fx-sx),2)+Math.pow((fy-sy),2))<(radf+rads)){ down = false; spriteC[spriteNum].active=false; yourScene.unregisterTouchArea(spriteC[spriteNum].sprite); Log.e("Collided",Boolean.toString(down)); } } } } spriteC[spriteNum].body = PhysicsFactory.createCircleBody(mPhysicsWorld, spriteC[spriteNum].sprite, BodyType.DynamicBody, FIXTURE_DEF); mPhysicsWorld.registerPhysicsConnector(new PhysicsConnector(spriteC[spriteNum].sprite, spriteC[spriteNum].body, true, true)); } } Better solution anyone? I know there is something to do with a handler, but I don't exactly know what that is or how to use one.

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  • Computing e^(-j) in C..

    - by Erkan H
    I need to compute imaginary exponential in C. As far as I know, there is no complex number library in C. It is possible to get e^x with exp(x) of math.h, but how can I compute the value of e^(-j), where j = sqrt(-1)?

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  • Getting Frequency Components with FFT

    - by ruhig brauner
    so I was able to solv my last problem but i stubmled upon the next already. So I want to make a simple spectrogram but in oder to do so I want to understand how FFT-libaries work and what they actually calculate and return. (FFT and Signal Processing is the number 1 topic I will get into as soon as I have time but right now, I only have time for some programming exercises in the evening. ;) ) Here I just summarized the most important parts: int framesPerSecond; int samplesPerSecond; int samplesPerCycle; // right now i want to refresh the spectogram every DoubleFFT_1D fft; WAVReader audioIn; double audioL[], audioR[]; double fftL[], fftR[]; ..... framesPerSecond = 30; audioIn= new WAVReader("Strobe.wav"); int samplesPerSecond = (int)audioIn.GetSampleRate(); samplesPerCycle = (int)(audioIn.GetSampleRate()/framesPerSecond); audioL = new double[samplesPerCycle*2]; audioR = new double[samplesPerCycle*2]; fftL = new double[samplesPerCycle]; fftR = new double[samplesPerCycle]; for(int i = 0; i < samplesPerCycle; i++) { // don't even know why,... fftL[i] = 0; fftR[i] = 0; } fft = new DoubleFFT_1D(samplesPerCycle); ..... for(int i = 0; i < samplesPerCycle; i++) { audioIn.GetStereoSamples(temp); audioL[i]=temp[0]; audioR[i]=temp[1]; } fft.realForwardFull(audioL); //still stereo fft.realForwardFull(audioR); System.out.println("Check"); for(int i = 0; i < samplesPerCycle; i++) { //storing the magnitude in the fftL/R arrays fftL[i] = Math.sqrt(audioL[2*i]*audioL[2*i] + audioL[2*i+1]*audioL[2*i+1]); fftR[i] = Math.sqrt(audioR[2*i]*audioR[2*i] + audioR[2*i+1]*audioR[2*i+1]); } So the question is, if I want to know, what frequencys are in the sampled signal, how do I calculate them? (When I want to print the fftL / fftR arrays, I get some exponential formes at both ends of the array.) Thx :)

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  • Applications: The Mathematics of Movement, Part 2

    - by TechTwaddle
    In part 1 of this series we saw how we can make the marble move towards the click point, with a fixed speed. In this post we’ll see, first, how to get rid of Atan2(), sine() and cosine() in our calculations, and, second, reducing the speed of the marble as it approaches the destination, so it looks like the marble is easing into it’s final position. As I mentioned in one of the previous posts, this is achieved by making the speed of the marble a function of the distance between the marble and the destination point. Getting rid of Atan2(), sine() and cosine() Ok, to be fair we are not exactly getting rid of these trigonometric functions, rather, replacing one form with another. So instead of writing sin(?), we write y/length. You see the point. So instead of using the trig functions as below, double x = destX - marble1.x; double y = destY - marble1.y; //distance between destination and current position, before updating marble position distanceSqrd = x * x + y * y; double angle = Math.Atan2(y, x); //Cos and Sin give us the unit vector, 6 is the value we use to magnify the unit vector along the same direction incrX = speed * Math.Cos(angle); incrY = speed * Math.Sin(angle); marble1.x += incrX; marble1.y += incrY; we use the following, double x = destX - marble1.x; double y = destY - marble1.y; //distance between destination and marble (before updating marble position) lengthSqrd = x * x + y * y; length = Math.Sqrt(lengthSqrd); //unit vector along the same direction as vector(x, y) unitX = x / length; unitY = y / length; //update marble position incrX = speed * unitX; incrY = speed * unitY; marble1.x += incrX; marble1.y += incrY; so we replaced cos(?) with x/length and sin(?) with y/length. The result is the same.   Adding oomph to the way it moves In the last post we had the speed of the marble fixed at 6, double speed = 6; to make the marble decelerate as it moves, we have to keep updating the speed of the marble in every frame such that the speed is calculated as a function of the length. So we may have, speed = length/12; ‘length’ keeps decreasing as the marble moves and so does speed. The Form1_MouseUp() function remains the same as before, here is the UpdatePosition() method, private void UpdatePosition() {     double incrX = 0, incrY = 0;     double lengthSqrd = 0, length = 0, lengthSqrdNew = 0;     double unitX = 0, unitY = 0;     double speed = 0;     double x = destX - marble1.x;     double y = destY - marble1.y;     //distance between destination and marble (before updating marble position)     lengthSqrd = x * x + y * y;     length = Math.Sqrt(lengthSqrd);     //unit vector along the same direction as vector(x, y)     unitX = x / length;     unitY = y / length;     //speed as a function of length     speed = length / 12;     //update marble position     incrX = speed * unitX;     incrY = speed * unitY;     marble1.x += incrX;     marble1.y += incrY;     //check for bounds     if ((int)marble1.x < MinX + marbleWidth / 2)     {         marble1.x = MinX + marbleWidth / 2;     }     else if ((int)marble1.x > (MaxX - marbleWidth / 2))     {         marble1.x = MaxX - marbleWidth / 2;     }     if ((int)marble1.y < MinY + marbleHeight / 2)     {         marble1.y = MinY + marbleHeight / 2;     }     else if ((int)marble1.y > (MaxY - marbleHeight / 2))     {         marble1.y = MaxY - marbleHeight / 2;     }     //distance between destination and marble (after updating marble position)     x = destX - (marble1.x);     y = destY - (marble1.y);     lengthSqrdNew = x * x + y * y;     /*      * End Condition:      * 1. If there is not much difference between lengthSqrd and lengthSqrdNew      * 2. If the marble has moved more than or equal to a distance of totLenToTravel (see Form1_MouseUp)      */     x = startPosX - marble1.x;     y = startPosY - marble1.y;     double totLenTraveledSqrd = x * x + y * y;     if ((int)totLenTraveledSqrd >= (int)totLenToTravelSqrd)     {         System.Console.WriteLine("Stopping because Total Len has been traveled");         timer1.Enabled = false;     }     else if (Math.Abs((int)lengthSqrd - (int)lengthSqrdNew) < 4)     {         System.Console.WriteLine("Stopping because no change in Old and New");         timer1.Enabled = false;     } } A point to note here is that, in this implementation, the marble never stops because it travelled a distance of totLenToTravelSqrd (first if condition). This happens because speed is a function of the length. During the final few frames length becomes very small and so does speed; and so the amount by which the marble shifts is quite small, and the second if condition always hits true first. I’ll end this series with a third post. In part 3 we will cover two things, one, when the user clicks, the marble keeps moving in that direction, rebounding off the screen edges and keeps moving forever. Two, when the user clicks on the screen, the marble moves towards it, with it’s speed reducing by every frame. It doesn’t come to a halt when the destination point is reached, instead, it continues to move, rebounds off the screen edges and slowly comes to halt. The amount of time that the marble keeps moving depends on how far the user clicks from the marble. I had mentioned this second situation here. Finally, here’s a video of this program running,

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  • LibGDX onTouch() method Array and flip method

    - by johnny-b
    How can I add this on my application. i want to use the onTouch() method from the implementation of the InputProcessor to kill the enemies on screen. how do i do that? do i have to do anything to the enemy class? also i am trying to add a Array of enemies and it keeps throwing exceptions or the bullet now is facing LEFT <--- again after I used the flip method in the bullet class. All the code is below so please anyone feel free to have a look thanks. please help Thank you M // This is the bullet class. public class Bullet extends Sprite { public static final float BULLET_HOMING = 6000; public static final float BULLET_SPEED = 300; private Vector2 velocity; private float lifetime; private Rectangle bul; public Bullet(float x, float y) { velocity = new Vector2(0, 0); setPosition(x, y); AssetLoader.bullet1.flip(true, false); AssetLoader.bullet2.flip(true, false); setSize(AssetLoader.bullet1.getWidth(), AssetLoader.bullet1.getHeight()); bul = new Rectangle(); } public void update(float delta) { float targetX = GameWorld.getBall().getX(); float targetY = GameWorld.getBall().getY(); float dx = targetX - getX(); float dy = targetY - getY(); float distToTarget = (float) Math.sqrt(dx * dx + dy * dy); dx /= distToTarget; dy /= distToTarget; dx *= BULLET_HOMING; dy *= BULLET_HOMING; velocity.x += dx * delta; velocity.y += dy * delta; float vMag = (float) Math.sqrt(velocity.x * velocity.x + velocity.y * velocity.y); velocity.x /= vMag; velocity.y /= vMag; velocity.x *= BULLET_SPEED; velocity.y *= BULLET_SPEED; bul.set(getX(), getY(), getOriginX(), getOriginY()); Vector2 v = velocity.cpy().scl(delta); setPosition(getX() + v.x, getY() + v.y); setOriginCenter(); setRotation(velocity.angle()); } public Rectangle getBounds() { return bul; } public Rectangle getBounds1() { return this.getBoundingRectangle(); } } // This is the class where i load all the images from public class AssetLoader { public static Texture texture; public static TextureRegion bg, ball1, ball2; public static Animation bulletAnimation, ballAnimation; public static Sprite bullet1, bullet2; public static void load() { texture = new Texture(Gdx.files.internal("SpriteN1.png")); texture.setFilter(TextureFilter.Nearest, TextureFilter.Nearest); bg = new TextureRegion(texture, 80, 421, 395, 30); bg.flip(false, true); ball1 = new TextureRegion(texture, 0, 321, 32, 32); ball1.flip(false, true); ball2 = new TextureRegion(texture, 32, 321, 32, 32); ball2.flip(false, true); bullet1 = new Sprite(texture, 380, 350, 45, 20); bullet1.flip(false, true); bullet2 = new Sprite(texture, 425, 350, 45, 20); bullet2.flip(false, true); TextureRegion[] balls = { ball1, ball2 }; ballAnimation = new Animation(0.16f, balls); ballAnimation.setPlayMode(Animation.PlayMode.LOOP); } Sprite[] bullets = { bullet1, bullet2 }; bulletAnimation = new Animation(0.06f, aims); bulletAnimation.setPlayMode(Animation.PlayMode.LOOP); } public static void dispose() { texture.dispose(); } // This is for the rendering or drawing onto the screen/canvas. public class GameRenderer { private Bullet bullet; private Ball ball; public GameRenderer(GameWorld world) { myWorld = world; cam = new OrthographicCamera(); cam.setToOrtho(true, 480, 320); batcher = new SpriteBatch(); // Attach batcher to camera batcher.setProjectionMatrix(cam.combined); shapeRenderer = new ShapeRenderer(); shapeRenderer.setProjectionMatrix(cam.combined); // Call helper methods to initialize instance variables initGameObjects(); initAssets(); } private void initGameObjects() { ball = GameWorld.getBall(); bullet = myWorld.getBullet(); scroller = myWorld.getScroller(); } private void initAssets() { ballAnimation = AssetLoader.ballAnimation; bulletAnimation = AssetLoader.bulletAnimation; } public void render(float runTime) { Gdx.gl.glClearColor(0, 0, 0, 1); Gdx.gl.glClear(GL30.GL_COLOR_BUFFER_BIT); batcher.begin(); batcher.disableBlending(); batcher.enableBlending(); batcher.draw(AssetLoader.ballAnimation.getKeyFrame(runTime), ball.getX(), ball.getY(), ball.getWidth(), ball.getHeight()); batcher.draw(AssetLoader.bulletAnimation.getKeyFrame(runTime), bullet.getX(), bullet.getY(), bullet.getOriginX(), bullet.getOriginY(), bullet.getWidth(), bullet.getHeight(), 1.0f, 1.0f, bullet.getRotation()); // End SpriteBatch batcher.end(); } } // this is to load the image etc on the screen i guess public class GameWorld { public static Ball ball; private Bullet bullet; private ScrollHandler scroller; public GameWorld() { ball = new Ball(480, 273, 32, 32); bullet = new Bullet(10, 10); scroller = new ScrollHandler(0); } public void update(float delta) { ball.update(delta); bullet.update(delta); scroller.update(delta); } public static Ball getBall() { return ball; } public ScrollHandler getScroller() { return scroller; } public Bullet getBullet() { return bullet; } } //This is the input handler class public class InputHandler implements InputProcessor { private Ball myBall; private Bullet bullet; private GameRenderer aims; // Ask for a reference to the Soldier when InputHandler is created. public InputHandler(Ball ball) { myBall = ball; } @Override public boolean touchDown(int screenX, int screenY, int pointer, int button) { return false; } @Override public boolean keyDown(int keycode) { return false; } @Override public boolean keyUp(int keycode) { return false; } @Override public boolean keyTyped(char character) { return false; } @Override public boolean touchUp(int screenX, int screenY, int pointer, int button) { return false; } @Override public boolean touchDragged(int screenX, int screenY, int pointer) { return false; } @Override public boolean mouseMoved(int screenX, int screenY) { return false; } @Override public boolean scrolled(int amount) { return false; } } i am rendering all graphics in a GameRender class and a gameworld class if you need more info please let me know I am trying to make the array work but keep finding that when an array is initialized then the bullet fips back to the original and ends up being backwards???? and if I create an array I keep getting Exceptions throw??? Thank you for any help given.

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  • Assembling a number-crunching computer [closed]

    - by tugrul büyükisik
    What is needed to make a GPU fully fed by CPU? Comparing their flops/s is enough? For example, if i could manage to make a very old(pentium-3) CPU with one of Nvidia-Fermi GPU, it would not be able to fed the gpu with data per sec. What is the criteria to fit CPU to GPU exactly when OpenCL or some similar work needed? Of course RAM and BUS will be chosen in a similar way but how exactly? Assume each GPU-core will calculate a sqrt and a division and an adding for 100 times for every itearation. Thanks.

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  • Simple command line calculator

    - by ldigas
    Had one years ago (on Win 3.1 or '95, I'm not sure). Anyways, it was a really simple program. Stood somewhere in PATH and enabled you to do something of a kind calc 5 + 28.3*sqrt(12) and it spit out the result. Anyone know of any such these days? Doesn't need to do anything fancy ... maybe it would just be nice if it had support for exponentials, but that's it. Anyone? p.s. Not interested in full blown solutions like Python or MATLAB.

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  • Is C# slower than VB.NET?

    - by Matt Winckler
    Believe it or not, despite the title, this is not a troll. Running some benchmarks this morning, my colleagues and I have discovered some strange things concerning performance, and I am wondering if we're doing something horribly wrong. We started out comparing C# vs. Delphi Prism calculating prime numbers, and found that Prism was about 30% faster. I figured maybe CodeGear did more optimization when generating IL (the exe was about twice as big as C#'s and had all sorts of different IL in it.) So I decided to write a test in VB.NET as well, assuming that Microsoft's compilers would end up writing essentially the same IL for each language. However, the result there was more shocking: C# was more than three times slower than VB running the same operations. The generated IL was different, but not extremely so, and I'm not good enough at reading it to understand the differences. As a fan of C#, this apparent slowness wounds me horribly, and I am left wondering: what in the world is going on here? Is it time to pack it all in and go write web apps in Ruby? ;-) I've included the code for each below--just copy it into a new VB or C# console app, and run. On my machine, VB finds 348513 primes in about 6.36 seconds. C# finds the same number of primes in 21.76 seconds. (I've got an Intel Core2 Quad Q6600 @2.4Ghz; on another Intel machine in the office the code for both runs much faster but the ratio is about the same; on an AMD machine here the timing is ~10 seconds for VB and ~13 for C#--much less difference, but C# is still always slower.) Both of the console applications were compiled in Release mode, but otherwise no project settings were changed from the defaults generated by Visual Studio 2008. Is it a generally-known fact that C#'s generated IL is worse than VB's? Or is this a strange edge case? Or is my code flawed somehow (most likely)? Any insights are appreciated. VB code Imports System.Diagnostics Module Module1 Private temp As List(Of Int32) Private sw As Stopwatch Private totalSeconds As Double Sub Main() serialCalc() End Sub Private Sub serialCalc() temp = New List(Of Int32)() sw = Stopwatch.StartNew() For i As Int32 = 2 To 5000000 testIfPrimeSerial(i) Next sw.Stop() totalSeconds = sw.Elapsed.TotalSeconds Console.WriteLine(String.Format("{0} seconds elapsed.", totalSeconds)) Console.WriteLine(String.Format("{0} primes found.", temp.Count)) Console.ReadKey() End Sub Private Sub testIfPrimeSerial(ByVal suspectPrime As Int32) For i As Int32 = 2 To Math.Sqrt(suspectPrime) If (suspectPrime Mod i = 0) Then Exit Sub End If Next temp.Add(suspectPrime) End Sub End Module C# Code using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Diagnostics; namespace FindPrimesCSharp { class Program { List<Int32> temp = new List<Int32>(); Stopwatch sw; double totalSeconds; static void Main(string[] args) { new Program().serialCalc(); } private void serialCalc() { temp = new List<Int32>(); sw = Stopwatch.StartNew(); for (Int32 i = 2; i <= 5000000; i++) { testIfPrimeSerial(i); } sw.Stop(); totalSeconds = sw.Elapsed.TotalSeconds; Console.WriteLine(string.Format("{0} seconds elapsed.", totalSeconds)); Console.WriteLine(string.Format("{0} primes found.", temp.Count)); Console.ReadKey(); } private void testIfPrimeSerial(Int32 suspectPrime) { for (Int32 i = 2; i <= Math.Sqrt(suspectPrime); i++) { if (suspectPrime % i == 0) return; } temp.Add(suspectPrime); } } }

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  • Using textureGrad for anisotropic integration approximation

    - by Amxx
    I'm trying to develop a real time rendering method using real time acquired envmap (cubemap) for lightning. This implies that my envmap can change as often as every frame and I therefore cannot use any method base on precomputation of the envmap (such as convolution with BRDF...) So far my method worked well with Phong BRDF. For specular contribution I direclty read the value in my sampleCube and I use mipmap levels + linear filter for simulating the roughtness of the material considered: int size = textureSize(envmap, 0).x; float specular_level = log2(size * sqrt(3.0)) - 0.5 * log2(ns + 1); vec3 env_specular = ks * specular_color * textureLod(envmap, l_g, specular_level); From this method I would like to upgrade to a microfacet based BRDF. I already have algorithm for evaluating the shape (including anisotropic direction) of the reflection but I cannot manage to read the values I want in my sampleCube. I believe I have to use textureGrad(envmap, l_g, X, Y); with l_g being the reflection direction in global space but I cannot manage to find which values to give to X and Y in order to correctly specify the area I want to consider. What value should I give to X and Y in orther for textureGrad(envmap, l_g, X, Y); to give the same result as textureLod(envmap, l_g, specular_level);

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  • boost::serialization with mutable members

    - by redmoskito
    Using boost::serialization, what's the "best" way to serialize an object that contains cached, derived values in mutable members, such that cached members aren't serialized, but on deserialization, they are initialized the their appropriate default. A definition of "best" follows later, but first an example: class Example { public: Example(float n) : num(n), sqrt_num(-1.0) {} float get_num() const { return num; } // compute and cache sqrt on first read float get_sqrt() const { if(sqrt_num < 0) sqrt_num = sqrt(num); return sqrt_num; } template <class Archive> void serialize(Archive& ar, unsigned int version) { ... } private: float num; mutable float sqrt_num; }; On serialization, only the "num" member should be saved. On deserialization, the sqrt_num member must be initialized to its sentinel value indicating it needs to be computed. What is the most elegant way to implement this? In my mind, an elegant solution would avoid splitting serialize() into separate save() and load() methods (which introduces maintenance problems). One possible implementation of serialize: template <class Archive> void serialize(Archive& ar, unsigned int version) { ar & num; sqrt_num = -1.0; } This handles the deserialization case, but in the serialization case, the cached value is killed and must be recomputed. Also, I've never seen an example of boost::serialize that explicitly sets members inside of serialize(), so I wonder if this is generally not recommended. Some might suggest that the default constructor handles this, for example: int main() { Example e; { std::ifstream ifs("filename"); boost::archive::text_iarchive ia(ifs); ia >> e; } cout << e.get_sqrt() << endl; return 0; } which works in this case, but I think fails if the object receiving the deserialized data has already been initialized, as in the example below: int main() { Example ex1(4); Example ex2(9); cout << ex1.get_sqrt() << endl; // outputs 2; cout << ex2.get_sqrt() << endl; // outputs 3; // the following two blocks should implement ex2 = ex1; // save ex1 to archive { std::ofstream ofs("filename"); boost::archive::text_oarchive oa(ofs); oa << ex1; } // read it back into ex2 { std::ifstream ifs("filename"); boost::archive::text_iarchive ia(ifs); ia >> ex2; } // these should be equal now, but aren't, // since Example::serialize() doesn't modify num_sqrt cout << ex1.get_sqrt() << endl; // outputs 2; cout << ex2.get_sqrt() << endl; // outputs 3; return 0; } I'm sure this issue has come up with others, but I have struggled to find any documentation on this particular scenario. Thanks!

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  • My first animation - Using SDL.NET C#

    - by Mark
    Hi all! I'm trying to animate a player object in my 2D grid when the user clicks somewhere in the screen. I got the following 4 variables: oX (Current player position X) oY (Current player position Y) dX (Destination X) dY (Destination Y) How can I make sure the player moves in a straight line to the new XY coordinates. The way I'm doing it now is really awfull and causes the player to first move along x axis, and finally in y axis. Can someone give me some guidance with the involved math cause I'm really not sure on how to accomplish this. Thank you for your time. Kind regards, Mark Update: It's working now but whats the right way to check if the current positions are equal to the target position? private static void MovePlayer(double x2, double y2, int duration) { double hX = x2 - m_PlayerPosition.X; double hY = y2 - m_PlayerPosition.Y; double Length = Math.Sqrt(Math.Pow(hX, 2) + Math.Pow(hY, 2)); hX = hX / Length; hY = hY / Length; while (m_PlayerPosition.X != Convert.ToInt32(x2) || m_PlayerPosition.Y != Convert.ToInt32(y2)) { m_PlayerPosition.X += Convert.ToInt32(hX * 1); m_PlayerPosition.Y += Convert.ToInt32(hY * 1); UpdatePlayerLocation(); } }

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  • Finding direction of travel in a world with wrapped edges

    - by crazy
    I need to find the shortest distance direction from one point in my 2D world to another point where the edges are wrapped (like asteroids etc). I know how to find the shortest distance but am struggling to find which direction it's in. The shortest distance is given by: int rows = MapY; int cols = MapX; int d1 = abs(S.Y - T.Y); int d2 = abs(S.X - T.X); int dr = min(d1, rows-d1); int dc = min(d2, cols-d2); double dist = sqrt((double)(dr*dr + dc*dc)); Example of the world : : T : :--------------:--------- : : : S : : : : : : T : : : :--------------: In the diagram the edges are shown with : and -. I've shown a wrapped repeat of the world at the top right too. I want to find the direction in degrees from S to T. So the shortest distance is to the top right repeat of T. but how do I calculate the direction in degreed from S to the repeated T in the top right? I know the positions of both S and T but I suppose I need to find the position of the repeated T however there more than 1. The worlds coordinates system starts at 0,0 at the top left and 0 degrees for the direction could start at West. It seems like this shouldn’t be too hard but I haven’t been able to work out a solution. I hope somone can help? Any websites would be appreciated.

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  • Scaling an image using the mouse in C#

    - by Gaax
    Hey guys... I'm trying to use the position of the mouse to calculate the scaling factor for scaling an image. Basically, the further you get away from the center of the image, the bigger it gets; and the closer to the center you get, the smaller it gets. I have some code so far but it's acting really strange and I have absolutely no more ideas. First I'll let you know, one thing I was trying to do is average out 5 distances to get a more smooth resize animation. Here's my code: private void pictureBoxScale_MouseMove(object sender, MouseEventArgs e) { if (rotateScaleMode && isDraggingToScale) { // For Scaling int sourceWidth = pictureBox1.Image.Width; int sourceHeight = pictureBox1.Image.Height; float dCurrCent = 0; // distance between the current mouse pos and the center of the image float dPrevCent = 0; // distance between the previous mouse pos and the center of the image System.Drawing.Point imgCenter = new System.Drawing.Point(); imgCenter.X = pictureBox1.Location.X + (sourceWidth / 2); imgCenter.Y = pictureBox1.Location.Y + (sourceHeight / 2); // Calculating the distance between the current mouse location and the center of the image dCurrCent = (float)Math.Sqrt(Math.Pow(e.X - imgCenter.X, 2) + Math.Pow(e.Y - imgCenter.Y, 2)); // Calculating the distance between the previous mouse location and the center of the image dPrevCent = (float)Math.Sqrt(Math.Pow(prevMouseLoc.X - imgCenter.X, 2) + Math.Pow(prevMouseLoc.Y - imgCenter.Y, 2)); if (smoothScaleCount < 5) { dCurrCentSmooth[smoothScaleCount] = dCurrCent; dPrevCentSmooth[smoothScaleCount] = dPrevCent; } if (smoothScaleCount == 4) { float currCentSum = 0; float prevCentSum = 0; for (int i = 0; i < 4; i++) { currCentSum += dCurrCentSmooth[i]; } for (int i = 0; i < 4; i++) { prevCentSum += dPrevCentSmooth[i]; } float scaleAvg = (currCentSum / 5) / (prevCentSum / 5); int destWidth = (int)(sourceWidth * scaleAvg); int destHeight = (int)(sourceHeight * scaleAvg); // If statement is for limiting the size of the image if (destWidth > (currentRotatedImage.Width / 2) && destWidth < (currentRotatedImage.Width * 3) && destHeight > (currentRotatedImage.Height / 2) && destWidth < (currentRotatedImage.Width * 3)) { AForge.Imaging.Filters.ResizeBilinear resizeFilter = new AForge.Imaging.Filters.ResizeBilinear(destWidth, destHeight); pictureBox1.Image = resizeFilter.Apply((Bitmap)currentRotatedImage); pictureBox1.Size = pictureBox1.Image.Size; pictureBox1.Refresh(); } smoothScaleCount = -1; } prevMouseLoc = e.Location; currentScaledImage = pictureBox1.Image; smoothScaleCount++; } }

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  • Resultant Vector Algorithm for 2D Collisions

    - by John
    I am making a Pong based game where a puck hits a paddle and bounces off. Both the puck and the paddles are Circles. I came up with an algorithm to calculate the resultant vector of the puck once it meets a paddle. The game seems to function correctly but I'm not entirely sure my algorithm is correct. Here are my variables for the algorithm: Given: velocity = the magnitude of the initial velocity of the puck before the collision x = the x coordinate of the puck y = the y coordinate of the puck moveX = the horizontal speed of the puck moveY = the vertical speed of the puck otherX = the x coordinate of the paddle otherY = the y coordinate of the paddle piece.horizontalMomentum = the horizontal speed of the paddle before it hits the puck piece.verticalMomentum = the vertical speed of the paddle before it hits the puck slope = the direction, in radians, of the puck's velocity distX = the horizontal distance between the center of the puck and the center of the paddle distY = the vertical distance between the center of the puck and the center of the paddle Algorithm solves for: impactAngle = the angle, in radians, of the angle of impact. newSpeedX = the speed of the resultant vector in the X direction newSpeedY = the speed of the resultant vector in the Y direction Here is the code for my algorithm: int otherX = piece.x; int otherY = piece.y; double velocity = Math.sqrt((moveX * moveX) + (moveY * moveY)); double slope = Math.atan(moveX / moveY); int distX = x - otherX; int distY = y - otherY; double impactAngle = Math.atan(distX / distY); double newAngle = impactAngle + slope; int newSpeedX = (int)(velocity * Math.sin(newAngle)) + piece.horizontalMomentum; int newSpeedY = (int)(velocity * Math.cos(newAngle)) + piece.verticalMomentum; for those who are not program savvy here is it simplified: velocity = v(moveX² + moveY²) slope = arctan(moveX / moveY) distX = x - otherX distY = y - otherY impactAngle = arctan(distX / distY) newAngle = impactAngle + slope newSpeedX = velocity * sin(newAngle) + piece.horizontalMomentum newSpeedY = velocity * cos(newAngle) + piece.verticalMomentum My Question: Is this algorithm correct? Is there an easier/simpler way to do what I'm trying to do?

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  • Scaling an image using the mouse in a WinForms application?

    - by Gaax
    I'm trying to use the position of the mouse to calculate the scaling factor for scaling an image. Basically, the further you get away from the center of the image, the bigger it gets; and the closer to the center you get, the smaller it gets. I have some code so far but it's acting really strange and I have absolutely no more ideas. First I'll let you know, one thing I was trying to do is average out 5 distances to get a more smooth resize animation. Here's my code: private void pictureBoxScale_MouseMove(object sender, MouseEventArgs e) { if (rotateScaleMode && isDraggingToScale) { // For Scaling int sourceWidth = pictureBox1.Image.Width; int sourceHeight = pictureBox1.Image.Height; float dCurrCent = 0; // distance between the current mouse pos and the center of the image float dPrevCent = 0; // distance between the previous mouse pos and the center of the image System.Drawing.Point imgCenter = new System.Drawing.Point(); imgCenter.X = pictureBox1.Location.X + (sourceWidth / 2); imgCenter.Y = pictureBox1.Location.Y + (sourceHeight / 2); // Calculating the distance between the current mouse location and the center of the image dCurrCent = (float)Math.Sqrt(Math.Pow(e.X - imgCenter.X, 2) + Math.Pow(e.Y - imgCenter.Y, 2)); // Calculating the distance between the previous mouse location and the center of the image dPrevCent = (float)Math.Sqrt(Math.Pow(prevMouseLoc.X - imgCenter.X, 2) + Math.Pow(prevMouseLoc.Y - imgCenter.Y, 2)); if (smoothScaleCount < 5) { dCurrCentSmooth[smoothScaleCount] = dCurrCent; dPrevCentSmooth[smoothScaleCount] = dPrevCent; } if (smoothScaleCount == 4) { float currCentSum = 0; float prevCentSum = 0; for (int i = 0; i < 4; i++) { currCentSum += dCurrCentSmooth[i]; } for (int i = 0; i < 4; i++) { prevCentSum += dPrevCentSmooth[i]; } float scaleAvg = (currCentSum / 5) / (prevCentSum / 5); int destWidth = (int)(sourceWidth * scaleAvg); int destHeight = (int)(sourceHeight * scaleAvg); // If statement is for limiting the size of the image if (destWidth > (currentRotatedImage.Width / 2) && destWidth < (currentRotatedImage.Width * 3) && destHeight > (currentRotatedImage.Height / 2) && destWidth < (currentRotatedImage.Width * 3)) { AForge.Imaging.Filters.ResizeBilinear resizeFilter = new AForge.Imaging.Filters.ResizeBilinear(destWidth, destHeight); pictureBox1.Image = resizeFilter.Apply((Bitmap)currentRotatedImage); pictureBox1.Size = pictureBox1.Image.Size; pictureBox1.Refresh(); } smoothScaleCount = -1; } prevMouseLoc = e.Location; currentScaledImage = pictureBox1.Image; smoothScaleCount++; } }

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  • Optimized algorithm for line-sphere intersection in GLSL

    - by fernacolo
    Well, hello then! I need to find intersection between line and sphere in GLSL. Right now my solution is based on Paul Bourke's page and was ported to GLSL this way: // The line passes through p1 and p2: vec3 p1 = (...); vec3 p2 = (...); // Sphere center is p3, radius is r: vec3 p3 = (...); float r = ...; float x1 = p1.x; float y1 = p1.y; float z1 = p1.z; float x2 = p2.x; float y2 = p2.y; float z2 = p2.z; float x3 = p3.x; float y3 = p3.y; float z3 = p3.z; float dx = x2 - x1; float dy = y2 - y1; float dz = z2 - z1; float a = dx*dx + dy*dy + dz*dz; float b = 2.0 * (dx * (x1 - x3) + dy * (y1 - y3) + dz * (z1 - z3)); float c = x3*x3 + y3*y3 + z3*z3 + x1*x1 + y1*y1 + z1*z1 - 2.0 * (x3*x1 + y3*y1 + z3*z1) - r*r; float test = b*b - 4.0*a*c; if (test >= 0.0) { // Hit (according to Treebeard, "a fine hit"). float u = (-b - sqrt(test)) / (2.0 * a); vec3 hitp = p1 + u * (p2 - p1); // Now use hitp. } It works perfectly! But it seems slow... I'm new at GLSL. You can answer this questions in two ways: Tell me there is no solution, showing some proof or strong evidence. Tell me about GLSL features (vector APIs, primitive operations) that makes the above algorithm faster, showing some example. Thanks a lot!

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  • Restart program from a certain line with an if statement?

    - by user1744093
    could anyone help me restart my program from line 46 if the user enters 1 (just after the comment where it states that the next code is going to ask the user for 2 inputs) and if the user enters -1 end it. I cannot think how to do it. I'm new to C# any help you could give would be great! class Program { static void Main(string[] args) { //Displays data in correct Format List<float> inputList = new List<float>(); TextReader tr = new StreamReader("c:/users/tom/documents/visual studio 2010/Projects/DistanceCalculator3/DistanceCalculator3/TextFile1.txt"); String input = Convert.ToString(tr.ReadToEnd()); String[] items = input.Split(','); Console.WriteLine("Point Latitude Longtitude Elevation"); for (int i = 0; i < items.Length; i++) { if (i % 3 == 0) { Console.Write((i / 3) + "\t\t"); } Console.Write(items[i]); Console.Write("\t\t"); if (((i - 2) % 3) == 0) { Console.WriteLine(); } } Console.WriteLine(); Console.WriteLine(); // Ask for two inputs from the user which is then converted into 6 floats and transfered in class Coordinates Console.WriteLine("Please enter the two points that you wish to know the distance between:"); string point = Console.ReadLine(); string[] pointInput = point.Split(' '); int pointNumber = Convert.ToInt16(pointInput[0]); int pointNumber2 = Convert.ToInt16(pointInput[1]); Coordinates distance = new Coordinates(); distance.latitude = (Convert.ToDouble(items[pointNumber * 3])); distance.longtitude = (Convert.ToDouble(items[(pointNumber * 3) + 1])); distance.elevation = (Convert.ToDouble(items[(pointNumber * 3) + 2])); distance.latitude2 = (Convert.ToDouble(items[pointNumber2 * 3])); distance.longtitude2 = (Convert.ToDouble(items[(pointNumber2 * 3) + 1])); distance.elevation2 = (Convert.ToDouble(items[(pointNumber2 * 3) + 2])); //Calculate the distance between two points const double PIx = 3.141592653589793; const double RADIO = 6371; double dlat = ((distance.latitude2) * (PIx / 180)) - ((distance.latitude) * (PIx / 180)); double dlon = ((distance.longtitude2) * (PIx / 180)) - ((distance.longtitude) * (PIx / 180)); double a = (Math.Sin(dlat / 2) * Math.Sin(dlat / 2)) + Math.Cos((distance.latitude) * (PIx / 180)) * Math.Cos((distance.latitude2) * (PIx / 180)) * (Math.Sin(dlon / 2) * Math.Sin(dlon / 2)); double angle = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a)); double ultimateDistance = (angle * RADIO); Console.WriteLine("The distance between your two points is..."); Console.WriteLine(ultimateDistance); //Repeat the program if the user enters 1, end the program if the user enters -1 Console.WriteLine("If you wish to calculate another distance type 1 and return, if you wish to end the program, type -1."); Console.ReadLine(); if (Convert.ToInt16(Console.ReadLine()) == 1); { //here is where I need it to repeat }

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  • Detecting walls or floors in pygame

    - by Serial
    I am trying to make bullets bounce of walls, but I can't figure out how to correctly do the collision detection. What I am currently doing is iterating through all the solid blocks and if the bullet hits the bottom, top or sides, its vector is adjusted accordingly. However, sometimes when I shoot, the bullet doesn't bounce, I think it's when I shoot at a border between two blocks. Here is the update method for my Bullet class: def update(self, dt): if self.can_bounce: #if the bullet hasnt bounced find its vector using the mousclick pos and player pos speed = -10. range = 200 distance = [self.mouse_x - self.player[0], self.mouse_y - self.player[1]] norm = math.sqrt(distance[0] ** 2 + distance[1] ** 2) direction = [distance[0] / norm, distance[1 ] / norm] bullet_vector = [direction[0] * speed, direction[1] * speed] self.dx = bullet_vector[0] self.dy = bullet_vector[1] #check each block for collision for block in self.game.solid_blocks: last = self.rect.copy() if self.rect.colliderect(block): topcheck = self.rect.top < block.rect.bottom and self.rect.top > block.rect.top bottomcheck = self.rect.bottom > block.rect.top and self.rect.bottom < block.rect.bottom rightcheck = self.rect.right > block.rect.left and self.rect.right < block.rect.right leftcheck = self.rect.left < block.rect.right and self.rect.left > block.rect.left each test tests if it hit the top bottom left or right side of the block its colliding with if self.can_bounce: if topcheck: self.rect = last self.dy *= -1 self.can_bounce = False print "top" if bottomcheck: self.rect = last self.dy *= -1 #Bottom check self.can_bounce = False print "bottom" if rightcheck: self.rect = last self.dx *= -1 #right check self.can_bounce = False print "right" if leftcheck: self.rect = last self.dx *= -1 #left check self.can_bounce = False print "left" else: # if it has already bounced and colliding again kill it self.kill() for enemy in self.game.enemies_list: if self.rect.colliderect(enemy): self.kill() #update position self.rect.x -= self.dx self.rect.y -= self.dy This definitely isn't the best way to do it but I can't think of another way. If anyone has done this or can help that would be awesome!

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  • Parsing mathematical experssions with two values that have parenthesis and minus signs

    - by user45921
    I'm trying to parse equations like these which only has two values or the square root of a certain value from a text file: 100+100 -100-100 -(100)+(-100) sqrt(100) by the minues signs, parenthesis and the operator symbol in the middle and the square root, and I have no idea how to start off... I've got the file part done and the simple calculation parts except that I couldnt get my program to solve the equations in the above. #include <stdio.h> #include <string.h> #include <stdlib.h> #include <math.h> main(){ FILE *fp; char buff[255], sym,sym2,del1,del2,del3,del4; double num1, num2; int ret; fp = fopen("input.txt","r"); while(fgets(buff,sizeof(buff),fp)!=NULL){ char *tok = buff; sscanf(tok,"%lf%c%lf",&num1,&sym,&num2); switch(sym){ case '+': printf("%lf\n", num1+num2); break; case '-': printf("%lf\n", num1-num2); break; case '*': printf("%lf\n", num1*num2); break; case '/': printf("%lf\n", num1/num2); break; default: printf("The input value is not correct\n"); break; } } fclose(fp); } that is what have I written for the other basic operations without parenthesis and the minus sign for the second value and it works great for the simple ones. I'm using a switch method to calculate the add, sub, mul and divide but I'm not sure how to properly use the sscanf function (if I am not using it properly) or if there is another way using a function like strtok to properly parse the parenthesis and the minus signs. Any kind help?

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  • How to calculate square root in PHP [explained] [on hold]

    - by Enes Imsirovic
    At first code ! Don't forget embed the JQuery ! <html> <head> <title>Simple jQuery and PHP Square Root example</title> <script src="js/jquery-1.10.1.js" type="text/javascript"></script> <script type="text/javascript"> $(document).ready(function() { $('#form').submit(function(){ var number = $('#number').val(); $.ajax({type:"post",url:"calculate.php",data:"number=" +number,success:function(msg){$('#result').hide(); $("#result").html("<h3>" + msg + "</h3>").fadeIn("slow"); } }); return false; }); }); </script> </head> <body> <form id="form" action="calculate.php" method="post"> Enter number: <input id="number" type="text" name="number" /> <input id="submit" type="submit" value="Calculate Square Root" name="submit"/> </form> <p id="result"></p> </body> </html> Second code witch would be connected with first : calculate.php <?php if($_POST['number']==null){ echo "Please Enter a Number"; }else { if (!is_numeric($_POST['number'])) { echo "Please enter only numbers"; }else{ echo "Square Root of " .$_POST['number'] ." is ".sqrt($_POST['number']); } } ?> Chiefly for begginers, to see the power of PHP :) xD Load this on your localhost.. PHP files and JS : https://mega.co.nz/#!Et8zWSBb!KX2PFxa2Pzw_l-wi6QU8xi_eKTlHbtQuBsT_DvXrifk At least it look like this : http://imgur.com/vNnDRQ3

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  • Automatically triggering standard spaceship controls to stop its motion

    - by Garan
    I have been working on a 2D top-down space strategy/shooting game. Right now it is only in the prototyping stage (I have gotten basic movement) but now I am trying to write a function that will stop the ship based on it's velocity. This is being written in Lua, using the Love2D engine. My code is as follows (note- object.dx is the x-velocity, object.dy is the y-velocity, object.acc is the acceleration, and object.r is the rotation in radians): function stopMoving(object, dt) local targetr = math.atan2(object.dy, object.dx) if targetr == object.r + math.pi then local currentspeed = math.sqrt(object.dx*object.dx+object.dy*object.dy) if currentspeed ~= 0 then object.dx = object.dx + object.acc*dt*math.cos(object.r) object.dy = object.dy + object.acc*dt*math.sin(object.r) end else if (targetr - object.r) >= math.pi then object.r = object.r - object.turnspeed*dt else object.r = object.r + object.turnspeed*dt end end end It is implemented in the update function as: if love.keyboard.isDown("backspace") then stopMoving(player, dt) end The problem is that when I am holding down backspace, it spins the player clockwise (though I am trying to have it go the direction that would be the most efficient at getting to the angle it would have to be) and then it never starts to accelerate the player in the direction opposite to it's velocity. What should I change in this code to get that to work? EDIT : I'm not trying to just stop the player in place, I'm trying to get it to use it's normal commands to neutralize it's existing velocity. I also changed math.atan to math.atan2, apparently it's better. I noticed no difference when running it, though.

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  • How to determine edges in an images optimally?

    - by SorinA.
    I recently was put in front of the problem of cropping and resizing images. I needed to crop the 'main content' of an image for example if i had an image similar to this: the result should be an image with the msn content without the white margins(left& right). I search on the X axis for the first and last color change and on the Y axis the same thing. The problem is that traversing the image line by line takes a while..for an image that is 2000x1600px it takes up to 2 seconds to return the CropRect = x1,y1,x2,y2 data. I tried to make for each coordinate a traversal and stop on the first value found but it didn't work in all test cases..sometimes the returned data wasn't the expected one and the duration of the operations was similar.. Any idea how to cut down the traversal time and discovery of the rectangle round the 'main content'? public static CropRect EdgeDetection(Bitmap Image, float Threshold) { CropRect cropRectangle = new CropRect(); int lowestX = 0; int lowestY = 0; int largestX = 0; int largestY = 0; lowestX = Image.Width; lowestY = Image.Height; //find the lowest X bound; for (int y = 0; y < Image.Height - 1; ++y) { for (int x = 0; x < Image.Width - 1; ++x) { Color currentColor = Image.GetPixel(x, y); Color tempXcolor = Image.GetPixel(x + 1, y); Color tempYColor = Image.GetPixel(x, y + 1); if ((Math.Sqrt(((currentColor.R - tempXcolor.R) * (currentColor.R - tempXcolor.R)) + ((currentColor.G - tempXcolor.G) * (currentColor.G - tempXcolor.G)) + ((currentColor.B - tempXcolor.B) * (currentColor.B - tempXcolor.B))) > Threshold)) { if (lowestX > x) lowestX = x; if (largestX < x) largestX = x; } if ((Math.Sqrt(((currentColor.R - tempYColor.R) * (currentColor.R - tempYColor.R)) + ((currentColor.G - tempYColor.G) * (currentColor.G - tempYColor.G)) + ((currentColor.B - tempYColor.B) * (currentColor.B - tempYColor.B))) > Threshold)) { if (lowestY > y) lowestY = y; if (largestY < y) largestY = y; } } } if (lowestX < Image.Width / 4) cropRectangle.X = lowestX - 3 > 0 ? lowestX - 3 : 0; else cropRectangle.X = 0; if (lowestY < Image.Height / 4) cropRectangle.Y = lowestY - 3 > 0 ? lowestY - 3 : 0; else cropRectangle.Y = 0; cropRectangle.Width = largestX - lowestX + 8 > Image.Width ? Image.Width : largestX - lowestX + 8; cropRectangle.Height = largestY + 8 > Image.Height ? Image.Height - lowestY : largestY - lowestY + 8; return cropRectangle; } }

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