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问题 I want to get the angle between two lines with respect to direction of the line. A normal dot product of the 2 vectors of the lines always returns the lowest angle between the two lines, which is not what I'm looking for. Example image: Blue lines: The lines I have Red lines: indication of the direction Green lines: failed attempt at a curving line that indicates the direction of the rotation I want. p0~p3: the x, y coordinates of the points of the lines. a: The angle I am looking to get. I

问题 I want to get the angle between two lines with respect to direction of the line. A normal dot product of the 2 vectors of the lines always returns the lowest angle between the two lines, which is not what I'm looking for. Example image: Blue lines: The lines I have Red lines: indication of the direction Green lines: failed attempt at a curving line that indicates the direction of the rotation I want. p0~p3: the x, y coordinates of the points of the lines. a: The angle I am looking to get. I

问题 What I have done: What I am looking for: I do not care about design, but I do not know how to connect buttons to Main button with lines that are similar to the second image. Note: I am creating buttons dynamically. Thus, I do not use XML file as I do not know how many lines/buttons I will have. protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.second_layout); // RelativeLayout FirstLayout = (RelativeLayout)findViewById(R.id.second

问题 I want to draw a line in my DirectX 11 application. I want it to have constant width (not depending on distance from camera), but it has to be a line in space (3D) , so something like lines of objects in wireframe mode . I will render my line in a scene full of other objects with some shaders. What would be the best and simplest way to achive it in DirectX 11 with C++ (not C#)? Code sample will be appreciated ;) 回答1: The most common solution would be to use D3D11_PRIMITIVE_TOPOLOGY_LINELIST

问题 how can i convert following code into windows batch command? Here is a perl script which is searching for a file in a while loop, if found it Exits. use strict; use warnings; my $filename = 'something.txt'; while (1) { if (-e $filename) { print "File Exists!"; exit; } } 回答1: This is a fairly straight-forward translation. The code should be pretty self-explanatory: @ECHO OFF SET LookForFile="C:\Path\To\File.txt" :CheckForFile IF EXIST %LookForFile% GOTO FoundIt REM If we get here, the file is

问题 I started my svg learning. And I want to do some skills bar with the svg line. But there is something I didn't understand. I create 2 lines per skills (one empty, and one with the percentage of knowledge). The problem is : The two first lines have half the height I give with stroke width. And the other lines have the good height... here is a jsbin : http://jsbin.com/lewimonize/edit?html,css,output Thanks in advance 回答1: Short answer: the line is clipped in half by the view box. When you draw

问题 I am trying to code a program that picks 3 random lines from a text file (that contains 50 lines) and outputs them to the screen. Here is my current code: string line; int random = 0; int numOfLines = 0; ifstream File("file.txt"); srand(time(0)); random = rand() % 50; while(getline(File, line)) { ++numOfLines; if(numOfLines == random) { cout << line; } } I can get it to print one random line like it does above but not three random lines. 回答1: What you should do depends on what exactly you

问题 I am trying to code a program that picks 3 random lines from a text file (that contains 50 lines) and outputs them to the screen. Here is my current code: string line; int random = 0; int numOfLines = 0; ifstream File("file.txt"); srand(time(0)); random = rand() % 50; while(getline(File, line)) { ++numOfLines; if(numOfLines == random) { cout << line; } } I can get it to print one random line like it does above but not three random lines. 回答1: What you should do depends on what exactly you

问题 I'm trying to delete a specific line by id from a file in C++ and here is my code: void deleteRow() { ifstream inDb("files/students.dat", ios::in); if(!inDb) { cerr << "File could no be opened!\n"; } cout << countRowsOfDb() << " records." << endl; Student *studentsArray[countRowsOfDb()]; int n = 0; while(inDb >> id >> name >> grade >> points >> type) { studentsArray[n] = new Student(id, name, grade, points, type); n++; } inDb.close(); for(int i = 0; i < countRowsOfDb(); i++) { cout <<

问题 I'm trying to delete a specific line by id from a file in C++ and here is my code: void deleteRow() { ifstream inDb("files/students.dat", ios::in); if(!inDb) { cerr << "File could no be opened!\n"; } cout << countRowsOfDb() << " records." << endl; Student *studentsArray[countRowsOfDb()]; int n = 0; while(inDb >> id >> name >> grade >> points >> type) { studentsArray[n] = new Student(id, name, grade, points, type); n++; } inDb.close(); for(int i = 0; i < countRowsOfDb(); i++) { cout <<