GlviewPort问题 - 获得伸展的相机视图

glViewport issue - getting stretched camera views

本文关键字：相机 视图 问题 GlviewPort      更新时间：2023-10-16

你好，我尝试在四个视口中拆分一个窗口，我想在每个视口中呈现一个场景。为简单起见，我简化了代码仅包含单个相机视图。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();
}

的结果是：球体的视图

有人知道为什么图像在不同的视口上伸展？

glViewport的第一个和第二个参数是viewport矩形的左下坐标（原点）。但是第三参数和第四参数是视口矩形的宽度和高度，而不是右上坐标。

这意味着在每种情况下必须是窗口大小的一半（w/2，h/2）的一半：

： 
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();
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