OpenGL Square没有深度

Question

我试图在OpenGL中绘制一个旋转的方块，但是方形没有深度，它只是看起来平坦，我期待一些边缘是对角的...我错过了一些明显的东西吗？

作为一方，z轴不是我想要的方式，我得知z轴正在通过屏幕，但我想看到它......

（摘录1）

- (void)drawRect:(NSRect)rect
{
    glEnable(GL_DEPTH_TEST);

    float _zoomFactor = 10.0;

    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
    glLoadIdentity();
    glClearColor(1.0,1.0,1.0,1.0);

    glViewport(0, 0, rect.size.width, rect.size.height);

    glMatrixMode( GL_PROJECTION );
    glLoadIdentity();

    float fieldOfView = 75.0;
    float imageAspectRatio = rect.size.width / rect.size.height;
    float nearClipPlane = 10.0;
    float farClipPlane = 300.0;

    float scale = tan(radians(fieldOfView * 0.5)) * nearClipPlane;
    float r = imageAspectRatio * scale, l = -r;
    float t = scale, b = -t;

    glFrustum(l*_zoomFactor, r*_zoomFactor, b*_zoomFactor, t*_zoomFactor, nearClipPlane, farClipPlane);
    glLoadIdentity();


    //-----------------------------

    //Draw 3-axis
    glPushMatrix();
    glLineWidth(2.5);

    //x
    glColor3f(1.0, 0.0, 0.0);
    glBegin(GL_LINES);
    glVertex3f(-1.0f, 0.0f, 0.0f);
    glVertex3f(1.0f, 0.0f, 0.0f);
    glEnd();

    //y
    glColor3f( 0.0f, 1.0f, 0.0f );
    glBegin(GL_LINES);
    glVertex3f(0.0f, -1.0f, 0.0f);
    glVertex3f(0.0f, 1.0f, 0.0f);
    glEnd();

    //z
    glColor3f(0.0, 0.0, 1.0);
    glBegin(GL_LINES);
    glVertex3f(0.0f, 0.0f, -1.0f);
    glVertex3f(0.0f, 0.0f, 1.0f);
    glEnd();
    glPopMatrix();



    //-----------------------------

    //draw a square
    glMatrixMode( GL_MODELVIEW );    // Select the modelview matrix
    glLoadIdentity();


    glPushMatrix();

    glRotatef( 45.0, 0.0f, 1.0f, 0.0f );

    glColor3f( 0.5f, 0.5f, 1.0f );      // Set color to blue just once
    glBegin( GL_QUADS );                // Draw a quad
    glVertex3f( 0.0f,  0.5f, 0.0f );   // Top left
    glVertex3f(  0.5f,  0.5f, 0.0f );   // Top right
    glVertex3f(  0.5f, 0.0f, 0.0f );   // Bottom right
    glVertex3f( 0.0f, 0.0f, 0.0f );   // Bottom left
    glEnd();                            // Quad is complete
    glPopMatrix();


    glFlush();
}

编辑1：

玩更多，我得到了我期待的一半，但其中一方是直的：

从此代码（代码段2）：

- (void)drawRect:(NSRect)rect
{
    glEnable(GL_DEPTH_TEST);

    float _zoomFactor = 1.0;

    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
    glLoadIdentity();
    glClearColor(1.0,1.0,1.0,1.0);

    glViewport(0, 0, rect.size.width, rect.size.height);

    glMatrixMode( GL_PROJECTION );
    glLoadIdentity();

    float fieldOfView = 45.0;
    float imageAspectRatio = rect.size.width / rect.size.height;
    float nearClipPlane = 0.1;
    float farClipPlane = 300.0;

    float scale = tan(radians(fieldOfView * 0.5)) * nearClipPlane;
    float r = imageAspectRatio * scale, l = -r;
    float t = scale, b = -t;



    glFrustum(l*_zoomFactor, r*_zoomFactor, b*_zoomFactor, t*_zoomFactor, nearClipPlane, farClipPlane);




    //-----------------------------

    glMatrixMode( GL_MODELVIEW );

    glTranslated(0,0,-2.0);




    //Draw 3-axis
    glPushMatrix();
    glLineWidth(2.5);

    //x
    glColor3f(1.0, 0.0, 0.0);
    glBegin(GL_LINES);
    glVertex3f(-1.0f, 0.0f, 0.0f);
    glVertex3f(1.0f, 0.0f, 0.0f);
    glEnd();

    //y
    glColor3f( 0.0f, 1.0f, 0.0f );
    glBegin(GL_LINES);
    glVertex3f(0.0f, -1.0f, 0.0f);
    glVertex3f(0.0f, 1.0f, 0.0f);
    glEnd();

    //z
    glColor3f(0.0, 0.0, 1.0);
    glBegin(GL_LINES);
    glVertex3f(0.0f, 0.0f, -1.0f);
    glVertex3f(0.0f, 0.0f, 1.0f);
    glEnd();
    glPopMatrix();



    //-----------------------------



    glPushMatrix();

    glRotatef( 45.0, 1.0f, 0.0f, 0.0f );

    glColor3f( 0.5f, 0.5f, 1.0f );      // Set color to blue just once
    glBegin( GL_QUADS );                // Draw a quad
    glVertex3f( 0.0f,  0.5f, 0.0f );   // Top left
    glVertex3f(  0.5f,  0.5f, 0.0f );   // Top right
    glVertex3f(  0.5f, 0.0f, 0.0f );   // Bottom right
    glVertex3f( 0.0f, 0.0f, 0.0f );   // Bottom left
    glEnd();                            // Quad is complete
    glPopMatrix();


    glFlush();
}