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  • Need the co-ordinates of innerPolygon

    - by user960567
    Let say I have this diagram, Given that i have all the co-ordinates of outer polygon and the distance between inner and outer polygon is d is also given. How to calculate the inner polygon co-ordinates? Edit: I was able to solved the issue by getting the mid-points of all lines. From these mid-points I can move d distance, So I can get three points. No I have 3 points and 3 slopes. From this, I can get three new equations. Simultaneously, solving the equation get the 3 points.

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  • What is going on in this SAT/vector projection code?

    - by ssb
    I'm looking at the example XNA SAT collision code presented here: http://www.xnadevelopment.com/tutorials/rotatedrectanglecollisions/rotatedrectanglecollisions.shtml See the following code: private int GenerateScalar(Vector2 theRectangleCorner, Vector2 theAxis) { //Using the formula for Vector projection. Take the corner being passed in //and project it onto the given Axis float aNumerator = (theRectangleCorner.X * theAxis.X) + (theRectangleCorner.Y * theAxis.Y); float aDenominator = (theAxis.X * theAxis.X) + (theAxis.Y * theAxis.Y); float aDivisionResult = aNumerator / aDenominator; Vector2 aCornerProjected = new Vector2(aDivisionResult * theAxis.X, aDivisionResult * theAxis.Y); //Now that we have our projected Vector, calculate a scalar of that projection //that can be used to more easily do comparisons float aScalar = (theAxis.X * aCornerProjected.X) + (theAxis.Y * aCornerProjected.Y); return (int)aScalar; } I think the problems I'm having with this come mostly from translating physics concepts into data structures. For example, earlier in the code there is a calculation of the axes to be used, and these are stored as Vector2, and they are found by subtracting one point from another, however these points are also stored as Vector2s. So are the axes being stored as slopes in a single Vector2? Next, what exactly does the Vector2 produced by the vector projection code represent? That is, I know it represents the projected vector, but as it pertains to a Vector2, what does this represent? A point on a line? Finally, what does the scalar at the end actually represent? It's fine to tell me that you're getting a scalar value of the projected vector, but none of the information I can find online seems to tell me about a scalar of a vector as it's used in this context. I don't see angles or magnitudes with these vectors so I'm a little disoriented when it comes to thinking in terms of physics. If this final scalar calculation is just a dot product, how is that directly applicable to SAT from here on? Is this what I use to calculate maximum/minimum values for overlap? I guess I'm just having trouble figuring out exactly what the dot product is representing in this particular context. Clearly I'm not quite up to date on my elementary physics, but any explanations would be greatly appreciated.

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  • Drawing a texture line between two vectors in XNA WP7

    - by Krav
    I want to create a simple graph maker in WP7. The goal is to draw a texture line between two vectors what the user defines with touch. I already made the rotation, and it is working, but not correctly, because it doesn't calculate the line's texture height, and because of that, there are too many overlapping textures. So it does draw the line, but too many of them. How could I calculate it correctly? Here is the code: public void DrawLine(Vector2 st,Vector2 dest,NodeUnit EdgeParent,NodeUnit EdgeChild) { float d = Vector2.Distance(st, dest); float rotate = (float)(Math.Atan2(st.Y - dest.Y, st.X - dest.X)); direction = new Vector2(((dest.X - st.X) / (float)d), (dest.Y - st.Y) / (float)d); Vector2 _pos = st; World.TheHive.Add(new LineHiveMind(linetexture, _pos, rotate, EdgeParent, EdgeChild,new List<LineUnit>())); for (int i = 0; i < d; i++) { World.TheHive.Last()._lines.Add(new LineUnit(linetexture, _pos, rotate, EdgeParent, EdgeChild)); _pos += direction; } } d is for the Distance of the st (Starting node) and dest (Destination node) rotate is for rotation direction calculates the direction between the starting and the destination node _pos is for starting position changing Thanks for any suggestions/help!

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  • Viewport.Unproject - Checking if a model intersects a large sprite

    - by Fibericon
    Let's say I have a sprite, drawn like this: spriteBatch.Draw(levelCannons[i].texture, levelCannons[i].position, null, alpha, levelCannons[i].rotation, Vector2.Zero, scale, SpriteEffects.None, 0); Picture levelCannon as being a laser beam that goes across the entire screen. I need to see if my 3d model intersects with the screen space inhabited by the sprite. I managed to dig up Viewport.Unproject, but that seems to only be useful when dealing with a single point in 2d space, rather than an area. What can I do in my case?

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  • Converting Degrees to X and Y Coordinate change

    - by gopgop
    I am using a float positioning system in my game. IE float x,y,z now I want to get the location of the mouse, then to fire an arrow to it. X0 = the players X location X1 = the mouse X location Y0 = the players Y location Y1 = the mouse Y location I want to make a method that the parameters are Degrees and it sets my Yspeed and my Xspeed accordingly to get to the mouse xy starting at player xy How do would I accomplish this?

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  • Swapping axis labels between 2D and 3D coordinates

    - by Will
    My game world is 3D. The map is only 2D, however. It is natural to think of the map as having an X and Y axis. And it is natural to think of the world has having an X, Y and Z axis, where Y is upwards. That is to say, X Y in 2D map coordinates is X Z in 3D coordinates. What conventions and approaches do you have to keeping things straight at a code level to make mapping between them natural? (Is Y usually upwards in 3D? Or do you have X and Z in map coordinates, or?)

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  • Determining if something is on the right or left side of an object?

    - by meds
    I have a character in a 3D world which is facing an arbitrary direction on a flat plane, the player can click on the left or right side of the character and based on which side is clicked on a different action happens. How can I determine which side the click occured on? Obviously for straight on ahead (0,0,1) I can simply use the x coordinate of the click point to determine if it's the left or right hand side, but what about other cases?

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  • Casting Type array to Generic array?

    - by George R
    The short version of the question - why can't I do this? I'm restricted to .NET 3.5. T[] genericArray; // Obviously T should be float! genericArray = new T[3]{ 1.0f, 2.0f, 0.0f }; // Can't do this either, why the hell not genericArray = new float[3]{ 1.0f, 2.0f, 0.0f }; Longer version - I'm working with the Unity engine here, although that's not important. What is - I'm trying to throw conversion between its fixed Vector2 (2 floats) and Vector3 (3 floats) and my generic Vector< class. I can't cast types directly to a generic array. using UnityEngine; public struct Vector { private readonly T[] _axes; #region Constructors public Vector(int axisCount) { this._axes = new T[axisCount]; } public Vector(T x, T y) { this._axes = new T[2] { x, y }; } public Vector(T x, T y, T z) { this._axes = new T[3]{x, y, z}; } public Vector(Vector2 vector2) { // This doesn't work this._axes = new T[2] { vector2.x, vector2.y }; } public Vector(Vector3 vector3) { // Nor does this this._axes = new T[3] { vector3.x, vector3.y, vector3.z }; } #endregion #region Properties public T this[int i] { get { return _axes[i]; } set { _axes[i] = value; } } public T X { get { return _axes[0];} set { _axes[0] = value; } } public T Y { get { return _axes[1]; } set { _axes[1] = value; } } public T Z { get { return this._axes.Length (Vector2 vector2) { Vector vector = new Vector(vector2); return vector; } public static explicit operator Vector(Vector3 vector3) { Vector vector = new Vector(vector3); return vector; } #endregion }

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  • Same address, multiple shared_ptr counters, is it forbidden by C++ standard?

    - by icando
    Suppose I have some needs to do the following (This is just some imaginative code for discussion of the C++ standard, thus I won't discuss why I design it this way, so don't bother me something like: your design is wrong.) T* ptr = new T; shared_ptr<T> p(ptr); shared_ptr<T> q(ptr, SomeDeleterThatDoesnotDeleteButDoSomeOtherStuff()); Suppose the logic guarantees that p or some of its copies lives longer than any copies of q, so practically there won't be any problem. My question is, is it forbidden by C++ standard, e.g. explicitly stated as UB by C++ standard, that different shared_ptr counters share the same address? Thanks.

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  • C++ static classes & shared_ptr memory leaks

    - by HardCoder1986
    Hello! I can't understand why does the following code produce memory leaks (I am using boost::shared_ptr with static class instance). Could someone help me? #include <crtdbg.h> #include <boost/shared_ptr.hpp> using boost::shared_ptr; #define _CRTDBG_MAP_ALLOC #define NEW new(_NORMAL_BLOCK, __FILE__, __LINE__) static struct myclass { static shared_ptr<int> ptr; myclass() { ptr = shared_ptr<int>(NEW int); } } myclass_instance; shared_ptr<int> myclass::ptr; int main() { _CrtSetDbgFlag(_CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF | _CRTDBG_CHECK_ALWAYS_DF | _CrtSetDbgFlag(_CRTDBG_REPORT_FLAG)); return 0; }

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  • Using logarithms to normalize a vector to avoid overflow

    - by muscicapa
    http://stackoverflow.com/questions/2293762/problem-with-arithmetic-using-logarithms-to-avoid-numerical-underflow-take-2 Having seen the above and having seen softmax normalization I was trying to normalize a vector while avoiding overflow - that is (x1 x2 x3 x4 ... xn) the normalized form for me has the sum of squares as 1.0 So what I thought of doing is s=(2*log(x1)+2*log(x2)+...+2*log(xn))/2 so the two factor can be taken off and finally the normalized vector is exp(log(x1)-s), , ..., exp(log(xn)-s) but I am evidently doing something wrong here, what?

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  • Numerical Integration of a vector in matlab?

    - by clowny
    Hello all! Well i have an issue. I have a vector of 358 numbers. I'd like to make a numerical integration of this vector, but i don't know the function of this one. I found that we can use trapz or quad, but i don't really understand how to integrate without the function. Thanx for any help!

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  • Initialization vector - DES/triple-des algorithm

    - by user312373
    Hi, In order to generate the encrypted data we would need to define a Key that should suffice generating the data. But in .net DESCryptoServiceProvider requires Key and Intialisation Vector to generate the encrypted data. In this regard, I would like to know the importance & the benefit gained by defining this initialisation vector field. Is this mandatory while encryption using DES algorithm. Pls share your thoughts on the same. Regards, Balu

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  • Checking for duplicates in a vector

    - by xbonez
    I have to check a vector for duplicates. What is the best way to approach this: I take the first element, compare it against all other elements in the vector. Then take the next element and do the same and so on. Is this the best way to do it, or is there a more efficient way to check for dups?

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  • Save all file names in a directory to a vector

    - by Bobby
    I need to save all ".xml" file names in a directory to a vector. To make a long story short, I cannot use the dirent API. It seems as if C++ does not have any concept of "directories". Once I have the filenames in a vector, I can iterate through and "fopen" these files. Is there an easy way to get these filenames at runtime?

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  • Converting a ts object to a plain old vector in R

    - by taskforce145
    I need to use a function on a vector that does not take a ts object. I'm trying to convert it to a plain old vector but I just can't seem to figure it out. I googled around but mostly people are trying to convert data types into ts object. I want to go the other way. Any help would be appreciated.

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  • Sort std::vector by an element inside?

    - by user146780
    I currently have a std::vector which holds std::vector of double. I'd want to sort it by the second element of the double vectore. ex: instead of sorting by MyVec[0] or myvec[1] I wat it to sort myVec[0] and myvec[1] based on myvec[0][1] myvec[1][1]. Basically sort by a contained value, not the objects in it. so if myvec[0][1] is less than myvec[1][1] then myvec[0] and myvec[1] will swap. Thanks

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  • C++ int vector to c#

    - by Stefan Koenen
    I'm doing a C# project and I want to call next_permutation from the algorithm library in C++. I found the way to call c++ functions in c# but i dont know how to get vectors from c++ and use it in c# (cause next_permutation require a int vector...) this is what I'm trying at the moment: extern void NextPermutation(vector<int>& permutation) { next_permutation (permutation.begin(),permutation.end()); } [DllImport("PEDLL.dll", CallingConvention = CallingConvention.Cdecl)] private static extern void NextPermutation(IntPtr test);

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  • Creating a series of vectors from a vector

    - by bluetongue
    I have a simple two vector dataframe (length=30) that looks something like this: > mDF Param1 w.IL.L 1 AuZgFw 0.5 2 AuZfFw 2 3 AuZgVw 74.3 4 AuZfVw 20.52 5 AuTgIL 80.9 6 AuTfIL 193.3 7 AuCgFL 0.2 8 ... I'd like to use each of the rows to form 30 single value numeric vectors with the name of the vector taken from mDF$Param1, so that: > AuZgFw [1] 0.5 etc I've tried melting and casting, but I suspect there may be an easier way?? Thanks in advance BT

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  • Insert SVG directly into Microsoft Publisher without converting file format

    - by nhinkle
    How can I insert an SVG image into a Microsoft Publisher 2010 document as a vector image without having to first convert it to a bitmap format like PNG? Copying and pasting an SVG file into a Publisher document does not work. I am aware that one can convert an SVG to EPS, and insert that, since Publisher accepts EPS files. The problem is that it is time consuming to convert, and often the colors come out wrong. If this is the only way to get vector graphics into Publisher, then is there a one-step method to convert an SVG to EPS and paste it into Publisher at one fell swoop?

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