Solved

DrawLine in DirectDraw

Posted on 2001-08-28
4
765 Views
Last Modified: 2010-05-18
Can someone give me an example of drawing simple lines in DirectDraw and C++. (2D)
0
Comment
Question by:franceskinm
4 Comments
 
LVL 14

Expert Comment

by:AlexVirochovsky
ID: 6431502
Small example of using DirectDraw you can find in
http://www.theparticle.com/pgraph.html
In http://www.cs.mcgill.ca/~kshaikh/ComputerGraphicsTutorial.html
Press softvare, lesson 3, display code, you can see, how
display line .
0
 
LVL 2

Author Comment

by:franceskinm
ID: 6431707
Thank you, but the examples you gave me use DrawPrimitive that goes trough 3D engine (if I understood right). What I wanted was an example of drawing in 2D directly to DirectDraw surface.
0
 

Expert Comment

by:Mithander
ID: 6432782
The way I've always done it is to lock a DC.  Use the windows api to draw on it, and release the DC.  I'm not at home right now, so I can't put up some code.  But if you look in the DirectX help for LockDC... Or something like that :)  you should be ok.  This is a pretty slow way to do it, but I don't think anything else is supported.
0
 
LVL 5

Accepted Solution

by:
FengYuan earned 200 total points
ID: 6435205
From my book (www.fengyuan.com)

void KLockedSurface::Line(int x0, int y0, int x1, int y1, DWORD color)
{
     int bps       = (bpp+7) / 8;                           // bytes-per-pixel
     BYTE * pPixel = pSurface + pitch * y0 + bps * x0; // first pixel address

     int error;                              // error
     int d_pixel_pos, d_error_pos;   // adjustment to pixel address and error when error>=0
     int d_pixel_neg, d_error_neg;     // adjustment to pixel address and error when error<0
     int dots;                              // number of dots to draw

     {
          int dx, dy, inc_x, inc_y;

          if ( x1 > x0 )
          {      dx = x1 - x0; inc_x =  bps; }
          else
          {     dx = x0 - x1; inc_x = -bps; }

          if ( y1 > y0 )
          {      dy = y1 - y0; inc_y =  pitch; }
          else
          {     dy = y0 - y1; inc_y = -pitch; }

          d_pixel_pos = inc_x + inc_y;    // move x and y
          d_error_pos = (dy - dx) * 2;
     
          if ( d_error_pos < 0 ) // x dominant
          {
               dots        = dx;
               error       = dy*2 - dx;
               d_pixel_neg = inc_x;          // move x only
               d_error_neg = dy * 2;
          }
          else
          {
               dots        = dy;
               error       = dx*2 - dy;
               d_error_pos = - d_error_pos;
               d_pixel_neg = inc_y;          // move y only
               d_error_neg = dx * 2;
          }
     }

     switch ( bps )
     {
          case 1:
               for (; dots>=0; dots--)               // 8-bpp pixel loop
               {
                    pPixel[0] = (BYTE) color;     // draw 8-bpp pixel
               
                    if ( error>=0 )
                    {  pPixel += d_pixel_pos; error  += d_error_pos; }
                    else
                    {  pPixel += d_pixel_neg; error  += d_error_neg; }
               }
               break;

          case 2:
               for (; dots>=0; dots--)               // 16-bpp pixel loop
               {
                    * (WORD *) pPixel = (WORD) color;     // draw 16-bpp pixel
               
                    if ( error>=0 )
                    {  pPixel += d_pixel_pos; error  += d_error_pos; }
                    else
                    {  pPixel += d_pixel_neg; error  += d_error_neg; }
               }
               break;

          case 3:
               for (; dots>=0; dots--)               // 24-bpp pixel loop
               {
                    * (RGBTRIPLE *) pPixel = * (RGBTRIPLE *) & color;     // draw 24-bpp pixel
               
                    if ( error>=0 )
                    {  pPixel += d_pixel_pos; error  += d_error_pos; }
                    else
                    {  pPixel += d_pixel_neg; error  += d_error_neg; }
               }
               break;

          case 4:
               for (; dots>=0; dots--)               // 32-bpp pixel loop
               {
                    * (DWORD *) pPixel = color;     // draw 32-bpp pixel
               
                    if ( error>=0 )
                    {  pPixel += d_pixel_pos; error  += d_error_pos; }
                    else
                    {  pPixel += d_pixel_neg; error  += d_error_neg; }
               }
               break;
     }
}

0

Featured Post

Netscaler Common Configuration How To guides

If you use NetScaler you will want to see these guides. The NetScaler How To Guides show administrators how to get NetScaler up and configured by providing instructions for common scenarios and some not so common ones.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Written by John Humphreys C++ Threading and the POSIX Library This article will cover the basic information that you need to know in order to make use of the POSIX threading library available for C and C++ on UNIX and most Linux systems.   [s…
  Included as part of the C++ Standard Template Library (STL) is a collection of generic containers. Each of these containers serves a different purpose and has different pros and cons. It is often difficult to decide which container to use and …
The viewer will learn how to pass data into a function in C++. This is one step further in using functions. Instead of only printing text onto the console, the function will be able to perform calculations with argumentents given by the user.
The viewer will be introduced to the member functions push_back and pop_back of the vector class. The video will teach the difference between the two as well as how to use each one along with its functionality.

770 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question