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Detect mouse clicks in OpenGL C ++

I am new to OpenGL and I am trying to create a game in which I have a raw image as the background. When the game starts, I show this image, and I want it to be clickable on it and then display another image. I tried to use the function glutMouseFunc, but when I try to run the program, I get a message saying that the program has stopped working. Here are some parts of my code: I have a global variable onMouse; if I press the mouse button, the variable takes the value 1, and if it has the value 1, I try to load the second image.

int onMouse;
void mouseClicks(int button, int state, int x, int y) {
    if(button == GLUT_LEFT_BUTTON && state == GLUT_DOWN) {
        onMouse = 1;
    }
}

And this is the main function:

//load first texture
texture = LoadTextureRAW( "2 Lock screen.raw", TRUE );
glutMouseFunc(mouseClicks);
if(onMouse == 1){
    //load second texture
    texture = LoadTextureRAW( "in_game.raw", TRUE );
}

What am I doing wrong?

EDIT , - . :

glutCreateWindow("Game");
texture = LoadTextureRAW( "2 Lock screen.raw", 1 );
glutDisplayFunc(display);

glutMouseFunc(mouseClicks);
glutKeyboardFunc(key);

glutMainLoop();

if(onMouse == 1){
        texture = LoadTextureRAW( "in_game.raw", 2 );
        glutDisplayFunc(display);
}

, :

glClearColor( 0.0f, 0.0f, 0.0f, 0.0f );
glClear( GL_COLOR_BUFFER_BIT );

// setup texture mapping
glEnable( GL_TEXTURE_2D );
glBindTexture( GL_TEXTURE_2D, texture );

glPushMatrix();
glBegin( GL_QUADS );
glTexCoord2d(1.0,0.0); glVertex3d(1.0,1.0, 1.0);
glTexCoord2d(0.0,0.0); glVertex3d(-1.0,1.0,1.0);
glTexCoord2d(0.0,1.0); glVertex3d(-1.0,-1.0, -1.0);
glTexCoord2d(1.0,1.0); glVertex3d(1.0,-1.0, 1.0);
glEnd();
glPopMatrix();
glutSwapBuffers();

// free the texture
FreeTexture( texture );
+5
3

.

glutMouseFunc(mouseClicks);

, .

if(onMouse == 1) {

, . , glutMainLoop , .

, , . , .

+7

?

, glutMouseFunc . GLUT (GLUT OpenGL BTW). - ( display GLUT).

GLUT (glutMainLoop() call), , , .

, ( )

// Define bitmasks for mouse status, we assume mice have less than 17 buttons
#define MB_LEFT   0
#define MB_MIDDLE 1
#define MB_RIGHT  2
#define LMB_PRESSED (1<<0)
#define MMB_PRESSED (1<<1)
#define RMB_PRESSED (1<<2)
#define LMB_CLICKED (1<<16)
#define MMB_CLICKED (1<<17)
#define RMB_CLICKED (1<<18)
#define MB_PRESSED(state, button) (1<<(button))
#define MB_CLICKED(state, button) (1<<((button)+16)))
#define MB_MASK_PRESSED 0x0000ffffL
#define MB_MASK_CLICKED 0xffff0000L

uint32_t mouse_status = 0;

void onMouseButton(int button, int state, int x, int y)
{
    int b;
    switch(button) {
    case GLUT_LEFT_BUTTON:   b=MB_LEFT;   break;
    case GLUT_MIDDLE_BUTTON: b=MB_MIDDLE; break;
    case GLUT_RIGHT_BUTTON:  b=MB_RIGHT;  break;
    }

    if(mouse_status & MB_PRESSED(b) && GLUT_UP == state) {
        mouse_status |= MB_CLICKED(b);
    }
    if( !(mouse_status & MB_PRESSED(b)) && GLUT_DOWN == state) {
        mouse_status = (mouse_status & ~(0L | MB_CLICKED(b))) | MB_PRESSED(b);
    }

    glutPostRedisplay();
}

void display(void)
{
    if(mouse_status & MB_CLICKED(MB_LEFT)) {
        /* do something */
        …

        /* clear the click flag */
        mouse_status &= ~MB_MASK_CLICKED;
    }
}

int main(…)
{
    …
    glutCreateWindow(…);
    glutDisplayFunc(display);
    glutMouseFunc(onMouseButton);

    glutMainLoop();
}

, , . . ( , , ).

+5

glutMouseFuncregisters a callback: a function called for certain events (here mouse events). These events are collected glutMainLoop, which has not yet been triggered when you test onMouse.

One more thing, although I can’t say for sure from a small snippet of the code that you provide, is that you are better off loading assets from the very beginning of the program, rather than waiting for a custom event to do so. Download them first and simply change textureto any that matches the texture you want to display.

+1
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