glutBitmapCharacter位置文本错误 [英] glutBitmapCharacter positions text wrong

问题描述

我正在尝试在屏幕上绘制一个简单的字符串(覆盖).

I'm trying to draw a simple string (overlay) on the screen.

根据我在互联网上发现的信息，我正在以这种方式使用它:

From what I've found over the internet, I'm using it this way:

void write(string text, int x, int y){
    glRasterPos2i(x,y);

    for(int i = 0; i < text.length(); i++){ 
        glutBitmapCharacter(GLUT_BITMAP_HELVETICA_12, text.data()[i]);
    }
}

但是它根据世界坐标绘制字符串.假设x和y设置为10，则会在世界上的(10,10,0)坐标处绘制它们.但是我只需要在2D窗口的(10,10)坐标处使用此字符串.

But it draws the string according to the world coordinates. Say, if x and y are set to 10, they are drawn at (10,10,0) coordinates in the world. But I simple need this string at window's (10,10) coordinates in 2D.

这是一个小项目的一部分，绘制方法如下.我不想对其进行太多更改，因为它可能会破坏项目中的其他内容.

This is part of a small project, and the draw method is given as below. I don't want to change it much as it may break something else in the project.

void disp(){
 // set viewing translation and object rotations
 glMatrixMode( GL_MODELVIEW );
 glLoadIdentity ();
 glTranslatef( INIT_VIEW_X, INIT_VIEW_Y, INIT_VIEW_Z );
 glRotatef( xRot, 1.0, 0.0, 0.0 );
 glRotatef( zRot, 0.0, 0.0, 1.0 );
 glScalef( scaleFactor, scaleFactor, scaleFactor );
 glClear(GL_COLOR_BUFFER_BIT);
 draw();
 glFlush();
}

我也不完全知道它们的作用，我认为将文本绘制为世界坐标与该代码中的某些内容有关.我还尝试了使用GLUT位图字体，但是它也不起作用.

I also don't exactly know what they do, and I think drawing the text to world coordinates have to do with something in this code. I've also tried Using GLUT bitmap fonts but it doesn't work either.

如何简单地在屏幕上绘制. OpenGL使事情变得复杂了.我尝试简单地写到窗口中，但是它会占用整个内容并转换为3D世界.我只是不想这样.

How can I simple draw onto the screen. OpenGL is over complicating things; I try to simply write to the window, but it takes the whole thing and translates into 3D world. I just don't want this.

推荐答案

从twall，是的，您需要同时清除模型视图和投影矩阵

From twall, yes you need to clear BOTH the modelview and projection matrices

//TEXT
glMatrixMode( GL_PROJECTION ) ;
glPushMatrix() ; // save
glLoadIdentity();// and clear
glMatrixMode( GL_MODELVIEW ) ;
glPushMatrix() ;
glLoadIdentity() ;

glDisable( GL_DEPTH_TEST ) ; // also disable the depth test so renders on top

glRasterPos2f( 0,0 ) ; // center of screen. (-1,0) is center left.
glColor4f(1.0f, 1.0f, 1.0f, 1.0f);
char buf[300];
sprintf( buf, "Oh hello" ) ;
const char * p = buf ;
do glutBitmapCharacter( GLUT_BITMAP_HELVETICA_18, *p ); while( *(++p) ) ;

glEnable( GL_DEPTH_TEST ) ; // Turn depth testing back on

glMatrixMode( GL_PROJECTION ) ;
glPopMatrix() ; // revert back to the matrix I had before.
glMatrixMode( GL_MODELVIEW ) ;
glPopMatrix() ;

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