CODEWITHSUNDEEP
c++opengl3dglut
Dan299
Dan299

Reputation: 165

Drawing stripes in OpenGL (C++)

I'm following the xoax.net tutorials for OpenGL in C++, and I am stuck on drawing the stripes in the U.S. flag using a for loop. I just get a blue screen (since I set the background colour to blue). Here is the code for the 'DrawStripes' function:

void DrawStripes() {
for (int x = 0; x < 13; ++x) {
    if (x % 2 == 0) {
        glColor3f(204/255, 0, 0);
    } else {
        glColor3f(1, 1, 1);
    }

    float fStartX = 0;
    float fEndX = 1;
    float fStartY = x * (1/13);
    float fEndY = (x + 1) * (1/13);

    if (x > 5) {
        fStartX = .76/1.9;
    }
    glBegin(GL_QUADS);
    glVertex3f(fStartX, fStartY, 0);
    glVertex3f(fEndX, fStartY, 0);
    glVertex3f(fEndX, fEndY, 0);
    glVertex3f(fStartX, fEndY, 0);
    glEnd();
    }
}

(I have put this function in the 'draw' function so it isn't just I'm not telling it to use the function) Any ideas?

--- EDIT --- Here are the 'Draw' and 'Initialize' functions:

void Draw() {
glClear(GL_COLOR_BUFFER_BIT);
    DrawStripes();
    glFlush();
}

void Initialize() {
glClearColor(0.0, 0.0, 0.5, 0.0);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
}

Upvotes: 1

Views: 1528

Answers (1)

Andreas Haferburg
Andreas Haferburg

Reputation: 5520

1/13 is 0 in C++. Been there, done that. For float constants you want to use 1.0f/13.0f.

Upvotes: 5

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