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gretty

Member Since 27 Dec 2009
Offline Last Active Mar 24 2014 06:51 PM
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Topics I've Started

Determine the 3d position of this vector

13 March 2014 - 10:57 PM

Hello

 

I have a rather simple mathematic problem to solve. However I am not that mathematically inclined so I'd appreciate if someone could provide advice on how I solve this mathematic problem:

 

For the following triangle I wish to find the location (X,Y & Z) of the point/vector C. How can I find this position?

 

295eb89.png

 

Using simple Pythagoras I can find the length of side Z. But how can I find the position of C? I am attempting to offset/parallel a straight line segment (side X) so I need to calculate the position of C.


Given a set of Vertices: Determine Boundary Vertices and Connection Order

02 February 2014 - 03:36 AM

Hello

I am looking for suggestions on algorithms I can use to determine the boundary points/vertices of a list of vertices. I also need to determine which boundary point connects to which other boundary point.

 

2wqzif8.jpg

I have my own solution but it involves alot of steps and is more procedurally based rather than mathematically based. Can you suggest any algorithms (both procedural and mathematic)?

My approach:

  •    - Organise the vertices into a Dictionary <int, List<Triangle>> vertexTriangleMap. Where the keys are the indexes of the vertices and the values are lists of the triangles that involve that vertex
  •    - Pick a random vertex(RV) then pick a random triangle involving that vertex. For eg; vertexTriangleMap[9][0]
  •    - Of the 2 other vertices in this triangle: Determine which involves the least triangles (the point w the least triangles = OV)
  •        - Search through OV's triangles looking for another triangle that involves the vertices OV AND RV:
  •            - if there is more than 1 triangle that involves these 2 points then that means that OV is NOT a boundary point else OV is a boundary point AND I know it connects to RV. OV now becomes RV and I can now repeat the process and I will determine which boundary points connect to which. I'll know when to stop when I reach the beginning again (the first RV).

       

 


Insert Image into SQLite3 Database: Unsure whats causing the error

24 November 2013 - 09:05 PM

Hello

 

Does anyone have experience inserting binary data into a SQlite3 database using the SQLite3 C API? Note I am using the SQLite3 C API functions imported into a C# application so I am writting C#. I am attempting to write a png to a SQLite3 database in C#. I have managed to correctly import the external DLL function sqlite3_bind_blob. But now I am getting an error when I write the image to my SQLite3 database. When I call the function sqlite3_bind_blob I get the error:

 

#define SQLITE_MISUSE      21   /* Library used incorrectly */

 

I am unsure how I am causing this error and what I can do to fix it. Can you tell me what I am doing wrong?

Heres my code:

// Include dll function (unsure if the parameter types are correct)
[DllImport("sqlite3", EntryPoint = "sqlite3_bind_blob", CallingConvention = CallingConvention.Cdecl)]
private static extern int sqlite3_bind_blob (IntPtr stmHandle, int iIndex, byte[] iParam, int iBytes, IntPtr iOperation);

// Code inside my function: Insert image into database
string query = "INSERT OR REPLACE INTO myTable(lat, lon, image) VALUES(-33.555, 151.457, ?1);";
    
if (sqlite3_prepare_v2 (_connection, query, query.Length, out stmHandle, IntPtr.Zero) != SQLITE_OK) {
    IntPtr errorMsg = sqlite3_errmsg (_connection);
    throw new SqliteException (Marshal.PtrToStringAnsi (errorMsg));
}

IntPtr SQLITE_TRANSIENT = new IntPtr(-1); // Represents SQLITE_TRANSIENT
int res = sqlite3_bind_blob (stmHandle, 1, blob, blob.Length, SQLITE_TRANSIENT);
// res always equals 21

From my debugging I know that the blob correctly contains valid png data because I can write it out to a file and open that file. I also know that the length of the blob is correct aswell.


Remove Multi-Line String from File

30 April 2013 - 05:07 PM

Hello

I am attempting to remove a multiline string from a file. The multiline string comes from another file and is read into a Batch variable. I then read the target file and search for this multiline string, if it exists I want to delete it from the target file.

Is this kind of functionality possible using Batch Windows Scripting? I really hope it is.

My code below is unable to remove the multiline string from the target file. It can successfully read the input file. Can you help me edit my script to search for and remove a multiline string from a file?

 

@echo off &setlocal enabledelayedexpansion

Set replace=
Set target=
Set infile=usermenuTest1.4d
Set outfile=usermenuTest2.4d

Rem Read file and store all contents in string
for /f "delims=" %%i in (%infile%) do set "target=!target! %%i"
echo %target%

Rem Remove the target string from outfile
@echo off & setlocal enabledelayedexpansion
for /f "tokens=1,* delims=¶" %%A in ( 'type "%outfile%"') do SET "string=%%A"
SET "modified=!string:%target%=%replace%!"
(echo(%modified%)>> "%outfile%"

ECHO.
PAUSE
ENDLOCAL

 

Essentially I want my script to remove the following bold text from a file:
 

// abc

// def

// hij

Menu "User" {
   Button "" {
      Walk_Right ""
   }
}

 


UML Diagrams used to model a websites architecture

07 April 2013 - 09:00 PM

Hello

 

I am attempting to understand what UML models/diagrams can be used to communicate a websites architecture.

 

The model or models' purpose is to communicate the architecture and functionality of a website to technical people (other software developers and engineers).
 

Website Features:
- The website is a recipe search engine
- Server side code is Python. Client side uses HTML, CSS, JQuery and AJAX.
- The website will have a Web Crawler/Indexer
- Infinite Scrolling is utilised when viewing search results so I will need to model asynchronous requests (both GET and POST).

 

The diagrams I am tending towards are Component Diagram (to communicate the architecture) and Sequence Diagram (to communicate the functionality of a HTTP request).

 

What diagrams have you used in the past to communicate the architecture and functionality of a website to technical people?

 


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