Opengl 2d 调整大小

Question

当我调整窗口大小时，我的原点不在左上角。并且二维坐标不是像素坐标：

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
rnd::initDraw();
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glOrtho(0.0, mainPanelx, mainPanely, 0.0, -1.0, 10.0);
glMatrixMode(GL_MODELVIEW);
//glPushMatrix();        ----Not sure if I need this
glLoadIdentity();
glDisable(GL_CULL_FACE);
glDisable(GL_DEPTH_TEST);
glClear(GL_DEPTH_BUFFER_BIT);

glBegin(GL_QUADS);
    glColor3f(1.0f, 0.0f, 0.0);
    glVertex2f(0.0, 0.0);
    glVertex2f(10.0, 0.0);
    glVertex2f(10.0, 10.0);
    glVertex2f(0.0, 10.0);
glEnd();
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
glutSwapBuffers();

调整大小功能：

void resize(int width, int height)
{
if (height == 0) height = 1;

glMatrixMode(GL_PROJECTION);
glLoadIdentity();

/* note we divide our width by our height to get the aspect ratio */
gluPerspective(45.0, width / height, 1.0, 400.0);
glMatrixMode(GL_MODELVIEW);
mainPanelx = width;
mainPanely = height;
std::cout<<mainPanelx<<", "<<mainPanely<<"\n";
}

如何获取窗口左上角的原点常量以及如何获取像素坐标中的 2d 坐标？

Answer 1

您忘记在调整大小函数中调用glViewport。

这意味着 OpenGL 仍将渲染到旧尺寸的视口。