About OpenGL, you shouldn’t worry about it. If you’re already working on implementing your design, you shouldn’t bother learning such a big API as OpenGL. Save it for a future project. Also, all Windows machines should have a software implementation of OpenGL (ensuring portability). If you were to do only line drawings with it, the hardware requirements would not be very high at all (i.e. no graphics card, low-end Pentium). You’d have to do some more work to get text in OpenGL, though.
Jonny DFrom: grimfang4@hotmail.com
To: sdl at lists.libsdl.org
Date: Sat, 5 Jan 2008 16:34:00 -0500
Subject: Re: [SDL] Linedrawing
Hey,
You can check out SPriG as well. It’s my up-to-date branch of SGE found here: http://pubpages.unh.edu/~jmb97
But to make your immediate search easy, here’s the code from SPriG/SGE for drawing a line:
//==================================================================================
// Draws a line
//==================================================================================
void _Line(SDL_Surface *surface, Sint16 x1, Sint16 y1, Sint16 x2, Sint16 y2, Uint32 color)
{
//if ( !clipLine(surface, &x1, &y1, &x2, &y2) )
//return;
Sint16 dx, dy, sdx, sdy, x, y;
dx = x2 - x1;
dy = y2 - y1;
sdx = (dx < 0) ? -1 : 1;
sdy = (dy < 0) ? -1 : 1;
dx = sdx * dx + 1;
dy = sdy * dy + 1;
x = y = 0;
Sint16 pixx = surface->format->BytesPerPixel;
Sint16 pixy = surface->pitch;
Uint8 *pixel = (Uint8*)surface->pixels + y1*pixy + x1*pixx;
pixx *= sdx;
pixy *= sdy;
if (dx < dy)
{
Sint32 tmp = dx;
dx = dy;
dy = Sint16(tmp);
tmp = pixx;
pixx = pixy;
pixy = tmp;
}
switch (surface->format->BytesPerPixel)
{
case 1:
{
for (x=0; x < dx; x++)
{
*pixel = color;
y += dy;
if (y >= dx)
{
y -= dx;
pixel += pixy;
}
pixel += pixx;
}
}
break;
case 2:
{
for (x=0; x < dx; x++)
{
*(Uint16*)pixel = color;
y += dy;
if (y >= dx)
{
y -= dx;
pixel += pixy;
}
pixel += pixx;
}
}
break;
case 3:
{
Uint8 rshift8 = surface->format->Rshift/8;
Uint8 gshift8 = surface->format->Gshift/8;
Uint8 bshift8 = surface->format->Bshift/8;
Uint8 ashift8 = surface->format->Ashift/8;
Uint8 R = (color>>surface->format->Rshift)&0xff;
Uint8 G = (color>>surface->format->Gshift)&0xff;
Uint8 B = (color>>surface->format->Bshift)&0xff;
Uint8 A = (color>>surface->format->Ashift)&0xff;
for (x=0; x < dx; x++)
{
*(pixel+rshift8) = R;
*(pixel+gshift8) = G;
*(pixel+bshift8) = B;
*(pixel+ashift8) = A;
y += dy;
if (y >= dx)
{
y -= dx;
pixel += pixy;
}
pixel += pixx;
}
}
break;
case 4:
{
for (x=0; x < dx; x++)
{
*(Uint32*)pixel = color;
y += dy;
if (y >= dx)
{
y -= dx;
pixel += pixy;
}
pixel += pixx;
}
}
break;
}
}
Good luck,
Jonny D
To: sdl at libsdl.org
From: norbert.melzer at gmx.net
Date: Sun, 6 Jan 2008 00:16:20 +0500
Subject: Re: [SDL] Linedrawing
Am Sat, 5 Jan 2008 17:08:42 +0000 (UTC) schrieb Zedr0n:
Norbert Melzer <norbert.melzer gmx.net> writes:
Hi Group!
I have a problem with drawing lines. I googled a bit and found finished
c-code for a Bresenham-line in the wikipedia, I adopted this code into my
C++ class (original code is the same, except that that the function is
embedded in a class and putpixel is now this->putpixel).
Any particular reason you don’t want to use openGL? If not, then you
can just use gl functions to draw a line and be done with it 
There is no particular reason for that, except, I didnt know that OGL can
do that On the other side, I wanted to keep requirements low. It is
hard to justify the requirement of a state of the art PC for a turnbased
strategy game with simple 2 dimensional linedrawings and some text…
Or is OGL not screwing requirements like this?
TIA
Norbert
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