c++ - 简单的 2D 应用程序，在使用 glutBitmapCharacter 时遇到问题

Question

我想简单地在屏幕上写任何东西。绘制矩形很容易。我试图将文本字符串横向叠加在“书”上。看起来很简单，但是...

请注意，我尝试从这些论坛中获取建议，所以 glDisable(GL_DEPTH_TEST);和 glDisable(GL_LIGHTING);可能没有必要。另外，有没有办法自己调试？我通常喜欢添加 cout << "i reached this far yay" << endl;但是当我把它放在 void Bookshelf() 中时它似乎不喜欢我...它给了我一个 C2381 错误('function' : redefinition; __declspec(noreturn) differs)

主要.cpp

#include "bookshelf.h"

void Initialize()
{
    glClearColor (1.0, 1.0, 1.0, 0.0 );
    glMatrixMode( GL_PROJECTION );
    glOrtho(0,899,899,0,1,0);
}
void main( int argc, char *argv[] )
{
    glutInit( &argc, argv );
    glutInitDisplayMode( GLUT_SINGLE | GLUT_RGB );
    glutInitWindowSize( 900, 900 );
    glutInitWindowPosition( 510, 100 );
    glutCreateWindow("Bookshelf - Ankit Ahuja");
    Initialize();
    glutDisplayFunc(Bookshelf);
    glutMainLoop();
}

书架.h

#include <GL/glut.h>  

void Bookshelf()
{
    glClear( GL_COLOR_BUFFER_BIT );
    glColor3f( 0.0, 0.0, 0.0 );
    glBegin( GL_QUADS );

    //Code that draws a bookshelf
    //Book1
    glColor3f( 1.0, 0.25, 0.25 );
    glVertex3i(240,70,0.5);
    glVertex3i(260,70,0.5);
    glVertex3i(260,180,0.5);
    glVertex3i(240,180,0.5);

    //BookTitle1
    glPushMatrix();
    glLoadIdentity();
    glDisable(GL_DEPTH_TEST);
    glRotatef(90f,0.0f,0.0f,0.0f);
    glColor3f( 0.0, 1.0, 0.0 );
    glDisable(GL_LIGHTING);
    glRasterPos3i(100,100,1);

    char text[50]="Alphabet Soup is the best guys";
    for(int i=0; i<50; i++) 
    {
        glutBitmapCharacter(GLUT_BITMAP_9_BY_15,(int)text[i]);
    }
    glPopMatrix();

    //Book2
    glColor3f( 0.8, 0.8, 0.0 );
    glVertex2i(270,70);
    glVertex2i(290,70);
    glVertex2i(290,180);
    glVertex2i(270,180);

    //More books and shelves
    glEnd();
    glFlush();
}

Answer 1

在显示文本之前，您应该使用 glOrtho 设置正交投影。

确保你在写你的文本之前正确地推/弹出投影和模型 View 矩阵，这样你就会看到类似的东西:

glMatrixMode(GL_PROJECTION);    //Select projection matrix
glPushMatrix();                 //save it
glLoadIdentity();                               

glMatrixMode(GL_MODELVIEW);    //Select modelview matrix
glPushMatrix();                //save it
glLoadIdentity();          

// set up ur glOrtho
glOrtho(...);

glutBitmapCharacter(...)                  

glMatrixMode(GL_PROJECTION);
glPopMatrix();                //Restore your old projection matrix

glMatrixMode(GL_MODELVIEW);
glPopMatrix();               //Restore old modelview matrix