OpenGL实现DDA画线算法

inline int round(const float a)
{
    return int(a + 0.5);
}

void GLApp::lineDDA(std::vector<glm::vec2> &verts,int x0, int y0, int xEnd, int yEnd)
{
    int dx = xEnd - x0, dy = yEnd - y0, steps, k;
    float xIncrement, yIncrement, x = x0, y = y0;

    if (fabs(dx) > fabs(dy))
    {
        steps = fabs(dx);
    }
    else
    {
        steps = fabs(dy);
    }
    xIncrement = float(dx) / float(steps);
    yIncrement = float(dy) / float(steps);

    verts.push_back(glm::vec2(round(x), round(y)));
    for (k = 0; k < steps; ++k)
    {
        x += xIncrement;
        y += yIncrement;
        verts.push_back(glm::vec2(round(x), round(y)));
    }
}