Opengl:3D 上的 2d HUD

2021-12-19 00:00:00 opengl c++

我查看了此处发布的一些关于此事的问题，但仍然无法弄清楚为什么我的 2d HUD 出现但使我的 3d 渲染世界消失.

I have looked at some questions posted here on the matter and still cant work out why my 2d HUD appears but makes my 3d Rendered world disappear.

似乎 2d 场景正在控制整个屏幕，所以我不时可以看到 3d 场景在 2d 场景中出现故障.因此，即使我只需要渲染一个 10 x 10 像素的四边形，它也会渲染它然后将屏幕的其余部分空白.

It seems that the 2d scene is taking control of the entire screen so every now and then I can see the 3d scene glitching through the 2d scene. So even though I its only ment to be rendering a quad thats 10 x 10 pixels it renders this then blanks out the rest of the screen.

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(40.0,(GLdouble)x/(GLdouble)y,0.5,20.0);
glMatrixMode(GL_MODELVIEW);
glViewport(0,0,x,y);
glClear(GL_COLOR_BUFFER_BIT);
glLoadIdentity();
glTranslatef(0.0,-0.5,-6.0);

glPushMatrix();

..Draw some 3d stuff...

glPopMatrix();
// Start 2d
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, SCREEN_WIDTH, SCREEN_HEIGHT, 0, -1, 1);

glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glColor3f(0.0f, 255.0f, 1.0f);
glBegin(GL_QUADS);
    glVertex2f(0.0, 0.0);
    glVertex2f(10.0, 0.0);
    glVertex2f(10.0, 10.0);
    glVertex2f(0.0, 10.0);
glEnd();

然后我交换缓冲区

这是我的代码顺序.就像它先生成 3d 空间然后生成 2d 空间，然后又抵消了 3d 空间.

Here is the order of my code. Its like it makes the 3d space then makes the 2d space which in turn cancels out the 3d space.

推荐答案

花了一点时间才弄明白，以防万一其他人有同样的问题:

Took a little while to figure it out, so just in case others have the same issues:

    ...After Drawing 3d Stuff...

glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glOrtho(0.0, SCREEN_WIDTH, SCREEN_HEIGHT, 0.0, -1.0, 10.0);
glMatrixMode(GL_MODELVIEW);
//glPushMatrix();        ----Not sure if I need this
glLoadIdentity();
glDisable(GL_CULL_FACE);

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();

// Making sure we can render 3d again
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
//glPopMatrix();        ----and this?

...Then swap buffers...

:)

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