Beginner - Impossible to Draw a simple Triangle with OpenGL

[sebcrj]

Hello,

First of all, sorry for this newbie thread, but I'm encountering problems to draw a simple triangle with SDL and OpenGL.

My IDE is Code::Blocks.
In debug mode, there is no Error/warning, the window is corretly open but nothing is showed inside.
Like no OpenGL commands are read...

Here is my little C++ program, Can you help me to figure out where is the problem ? thx

#include <SDL2/SDL.h>
#include <GL/gl.h>
#include <GL/glu.h>

int main(int argc, char ** argv) {
SDL_Window* mainWindow = SDL_CreateWindow(
"OpenGL Triangle",
SDL_WINDOWPOS_UNDEFINED,
SDL_WINDOWPOS_UNDEFINED,
640,
480,
SDL_WINDOW_OPENGL
);

bool continuer = true;

SDL_Event event;

while (continuer) {
SDL_WaitEvent(&event);
switch(event.type) {
case SDL_QUIT:
continuer = false;
}

glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);

glBegin(GL_TRIANGLES);
glColor3ub(255,0,0);
glVertex2d(-0.75,-0.75);
glColor3ub(0,255,0);
glVertex2d(0,0.75);
glColor3ub(0,0,255);
glVertex2d(0.75,-0.75);
glEnd();

glFlush();

SDL_GL_SwapWindow(mainWindow);
}

SDL_Quit();

return 0;
}

[sebcrj]

I tried to figure it out on my own but still stuck.

I turned the Build Target to Console in order to view "Cout"

1. I tried to check OpenGL commands by adding this before "glBegin"

glEnable(GL_TEXTURE_2D);
if (glIsEnabled(GL_TEXTURE_2D)) {
cout << "OK\n";
}
else {
cout << "NOK\n";
}

With this, I get "NOK" after the SDL window openning.

2. After, I tried to get the GL flag error by adding before glBegin and also between glBegin/glEnd :

cout << "GL Flag Error : " << glGetError() << "\n";

With this, I get a 1282 error flag which refer to INVALID_OPERATION

From some another forum, some say that it's du to an error between glBegin/glEnd, but for me I don't see any error (hope so)

3. Finally, I tried to retreive the OpenGL Version by adding :

const unsigned char* glVer = glGetString(GL_VERSION);
cout << glVer << "\n";

No build error, but the program stucks at this line...

Please help me !