Solved

DrawLine in DirectDraw

Posted on 2001-08-28
4
754 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

How to run any project with ease

Manage projects of all sizes how you want. Great for personal to-do lists, project milestones, team priorities and launch plans.
- Combine task lists, docs, spreadsheets, and chat in one
- View and edit from mobile/offline
- Cut down on emails

Join & Write a Comment

Unlike C#, C++ doesn't have native support for sealing classes (so they cannot be sub-classed). At the cost of a virtual base class pointer it is possible to implement a pseudo sealing mechanism The trick is to virtually inherit from a base class…
Templates For Beginners Or How To Encourage The Compiler To Work For You Introduction This tutorial is targeted at the reader who is, perhaps, familiar with the basics of C++ but would prefer a little slower introduction to the more ad…
The goal of the tutorial is to teach the user how to use functions in C++. The video will cover how to define functions, how to call functions and how to create functions prototypes. Microsoft Visual C++ 2010 Express will be used as a text editor an…
The viewer will learn how to use the return statement in functions in C++. The video will also teach the user how to pass data to a function and have the function return data back for further processing.

757 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

Need Help in Real-Time?

Connect with top rated Experts

20 Experts available now in Live!

Get 1:1 Help Now