Eric Lilja wrote:
Hello, I'm using a fully updated cygwin and mingw developement binaries
of SDL (version 1.2.11). Consider the following program:
//#include <windows.h>
#include <SDL.h>
#include <GL/gl.h>
#include <cassert>
static void
display()
{
glClear(GL_COLOR_BUFFER_BIT);
glBegin(GL_POLYGON);
glVertex2f(-0.5f,-0.5f);
glVertex2f(-0.5f, 0.5f);
glVertex2f( 0.5f, 0.5f);
glVertex2f( 0.5f,-0.5f);
glEnd();
SDL_GL_SwapBuffers();
}
int
main(int argc, char *argv[])
{
(void)argc;
(void)argv;
int retval = SDL_Init(SDL_INIT_VIDEO);
assert(retval == 0);
SDL_Surface *surface = SDL_SetVideoMode(640, 480, 0, SDL_OPENGL);
assert(surface != NULL);
SDL_WM_SetCaption("Simple SDL/OpenGL demo", NULL);
SDL_Event event;
//wglGetProcAddress("foo");
while (true)
{
while (SDL_PollEvent(&event))
{
switch (event.type)
{
case SDL_QUIT:
{
SDL_Quit();
exit(EXIT_SUCCESS);
}
}
}
display();
}
assert(0); /* Not reached. */
}
Makefile I use:
CXX = g++
CXXFLAGS = -Wall -Wextra -std=c++98 -pedantic -g -O0 -I
~/SDL-1.2.11/include -c
LDFLAGS = -L ~/SDL-1.2.11/lib -lSDL -lopengl32 -o $(EXEC)
EXEC = 1-1.exe
OBJECTS = simple_1-1.o
all: $(OBJECTS)
$(CXX) $^ $(LDFLAGS)
%.o: %.cpp
$(CXX) $(CXXFLAGS) $<
clean:
rm -f $(OBJECTS) $(EXEC) *~ *.stackdump
This compiles, links, and runs just fine. However, now I want to use one
of the wgl-functions (namely wglGetProcAddress). For that I have to
include <windows.h>. The program compiles, but the linker fails with:
$ make
g++ -Wall -Wextra -std=c++98 -pedantic -g -O0 -I ~/SDL-1.2.11/include -c
simple_1-1.cpp
g++ simple_1-1.o -L ~/SDL-1.2.11/lib -lSDL -lopengl32 -o 1-1.exe
/usr/lib/gcc/i686-pc-cygwin/3.4.4/../../../libcygwin.a(libcmain.o):(.text+0xab):
undefined reference to [EMAIL PROTECTED]'
OK, so I tried replacing the main() function with a WinMain() and now it
links under cygwin too. This is not necessary under MSVC++, though. I
wonder if it can be solved? Right now I use #ifdef:s to work around it.
I tried adding -lSDLmain and -mwindows to the linker options, but it
didn't help. Still the same linking error. Posting this to both the
cygwin and sdl mailing list, hope that it doesn't offend anyone.
Attaching the working program and Makefile. What must I do to get it to
work? Works just fine under MSVC++ but I'd much rather use cygwin/gcc.
/ E
------------------------------------------------------------------------
#include <SDL.h>
#include <GL/gl.h>
#include <cassert>
static void
display()
{
glClear(GL_COLOR_BUFFER_BIT);
glBegin(GL_POLYGON);
glVertex2f(-0.5f,-0.5f);
glVertex2f(-0.5f, 0.5f);
glVertex2f( 0.5f, 0.5f);
glVertex2f( 0.5f,-0.5f);
glEnd();
SDL_GL_SwapBuffers();
}
int
main(int argc, char *argv[])
{
(void)argc;
(void)argv;
int retval = SDL_Init(SDL_INIT_VIDEO);
assert(retval == 0);
SDL_Surface *surface = SDL_SetVideoMode(640, 480, 0, SDL_OPENGL);
assert(surface != NULL);
SDL_WM_SetCaption("Simple SDL/OpenGL demo", NULL);
SDL_Event event;
while (true)
{
while (SDL_PollEvent(&event))
{
switch (event.type)
{
case SDL_QUIT:
{
SDL_Quit();
exit(EXIT_SUCCESS);
}
}
}
display();
}
assert(0); /* Not reached. */
}
------------------------------------------------------------------------
CXX = g++
CXXFLAGS = -Wall -Wextra -std=c++98 -pedantic -g -O0 -I ~/SDL-1.2.11/include -c
LDFLAGS = -L ~/SDL-1.2.11/lib -lSDL -lopengl32 -o $(EXEC)
EXEC = 1-1.exe
OBJECTS = simple_1-1.o
all: $(OBJECTS)
$(CXX) $^ $(LDFLAGS)
%.o: %.cpp
$(CXX) $(CXXFLAGS) $<
clean:
rm -f $(OBJECTS) $(EXEC) *~ *.stackdump
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