Question

您好，我尝试将一个窗口拆分为四个视口，我想在每个视口中渲染一个场景。为简单起见，我将代码简化为仅包含单个摄像机视图。代码大致如下：

void setup_trf(const PolarCoords& pc, double aspect)
{
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(60, aspect, 0.01, 1000);
    //glFrustum(-1.0, 1.0, -1.0, 1.0, 1.5, 20.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    double eye_x, eye_y, eye_z;
    pc.to_cartesian(eye_x, eye_y, eye_z);

    double look_x = 0;
    double look_y = 0;
    double look_z = 0;

    double up_x = 0;
    double up_y = 0;
    double up_z = 1;
    gluLookAt(
        eye_x, eye_y, eye_z,
        look_x, look_y, look_z,
        up_x, up_y, up_z);
}

void draw_scene(int w, int h) {
    glClearColor(0.0f, 0.75f, 1.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    double aspect = w / double(h);

    glViewport(0, h / 2, w / 2, h);
    setup_trf(app_state.m_polar, aspect);
    draw_sphere();

    glViewport(w / 2, h / 2, w, h);
    setup_trf(app_state.m_polar, aspect*0.5);
    draw_sphere();

    glViewport(0, 0, w / 2, h/2);
    setup_trf(app_state.m_polar, aspect);
    draw_sphere();

    glViewport(w / 2, 0, w, h / 2);
    setup_trf(app_state.m_polar, aspect);
    draw_sphere();
}

结果如下： view of the sphere

有人知道为什么图像会在不同的视口中拉伸吗？

Answer 1

glViewport的第一和第二参数是视口矩形的左下角坐标（原点）。但是第3个和第4个参数是视口矩形的宽度和高度，而不是右上角的坐标。

这意味着在每种情况下，第3个和第4个参数必须为窗口大小的一半（w/2，h/2）：

glViewport(0, h/2, w/2, h/2);
setup_trf(app_state.m_polar, aspect);
draw_sphere();

glViewport(w/2, h/2, w/2, h/2);
setup_trf(app_state.m_polar, aspect);
draw_sphere();

glViewport(0, 0, w/2, h/2);
setup_trf(app_state.m_polar, aspect);
draw_sphere();

glViewport(w/2, 0, w/2, h/2);
setup_trf(app_state.m_polar, aspect);
draw_sphere();

glViewport问题-拉伸摄像机视图

1 个答案: