鼠标拖动OpenGL/GLUT中的对象

感谢到目前为止的所有回复.

我已经知道如何做到这一点,所以我将继续回答我自己的问题.

我使用GLUT作为鼠标处理程序:

单击鼠标并移动(glutMotionFunc)时,将调用拖动功能.

在拖动功能中,鼠标坐标(x,y)在转换为窗口坐标时转换为Points结构.

如果鼠标位于正方形内,则通过更改其坐标并重新显示来拖动方块.

我仍然是OpenGL和C++的新手,所以我为凌乱的编码道歉.我这样做有点沮丧,因为重绘的方块使得它看起来像是光标卡在中心.出于学习目的,我欢迎这个问题的替代解决方案和对我的代码的批评.

CODE(包含过剩和使用命名空间std):

// points structure made of two coordinates; x and y
struct Points
{
    float x,y;  // initializor
    Points() { x = 0.0; y = 0.0; } // constructor

    Points(float _x, float _y) : x(_x), y(_y) {}
};

// square made of 4 points
class Square
{
public:
    Points pts[4]; // square structure
    Square(); // initialize constructor

    void draw(Square *sqr); // draw square
    Points mouse(int x, int y); // get mouse coordintaes
    Square* drag(Square *sqr, Points *mouse); // change points of sqr
};

// square constructor
Square::Square()
{
    pts[0] = Points(0.2,0.2);
    pts[1] = Points(0.4,0.2);
    pts[2] = Points(0.4,0.4);
    pts[3] = Points(0.2,0.4);
};

// draw function
void Square::draw(Square *sqr)
{
    // draw square fill
    int i;
    glColor3f(0.2, 0.2, 0.2);
    glBegin(GL_QUADS);
    for (i = 0; i < 4; ++i)
    {
        glVertex2f(sqr->pts[i].x, sqr->pts[i].y);
    }
    glEnd();
    // draw square points
    i = 0;

    glColor3f(1.0, 1.0, 1.0);
    glBegin(GL_POINTS);
    for (i = 0; i < 4; ++i)
    {
        glVertex2f(sqr->pts[i].x, sqr->pts[i].y);
    }
    glEnd();
}

// mouse function
Points Square::mouse(int x, int y)
{
    int windowWidth = 400, windowHeight = 400;
    return Points(float(x)/windowWidth, 1.0 - float(y)/windowHeight);
}

// drag function
Square* Square::drag(Square *sqr, Points *mouse)
{
    sqr->pts[0].x = mouse->x - 0.1;
    sqr->pts[0].y = mouse->y - 0.1;
    sqr->pts[1].x = mouse->x + 0.1;
    sqr->pts[1].y = mouse->y - 0.1;

    sqr->pts[3].x = mouse->x - 0.1;
    sqr->pts[3].y = mouse->y + 0.1;

    sqr->pts[2].x = mouse->x + 0.1;
    sqr->pts[2].y = mouse->y + 0.1;

    return sqr;
}

// GLOBAL

// create square object
Square* sqr = new Square;


// display at start
void display() {
    glClear(GL_COLOR_BUFFER_BIT);
    sqr->draw(sqr);
    glFlush();
}

// drag function
void drag (int x, int y)
{
    // int x and y of mouse converts to screen coordinates
    // returns the point as mousePt
    Points mousePt = sqr->mouse(x,y);
    //create pointer to window point coordinates
    Points* mouse = &mousePt;

    // if the mouse is within the square
    if (mouse->x > sqr->pts[0].x && mouse->y > sqr->pts[0].y)
    {       
        if (mouse->x < sqr->pts[2].x && mouse->y < sqr->pts[2].y)
        {
            // then drag by chaning square coordinates relative to mouse
            sqr->drag(sqr,mouse);
            glutPostRedisplay();
        }
    }
}


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

int main(int iArgc, char** cppArgv) {

    glutInit(&iArgc, cppArgv);
    glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
    glutInitWindowSize(400, 400);
    glutInitWindowPosition(200, 200);
    glutCreateWindow("Move Box");


    glutMotionFunc(drag);

    Initialize();
    glutDisplayFunc(display);
    glutMainLoop();
    return 0;
}