Как отображать текст и некоторые точки с помощью OpenGL/GLUT?

Question

Этот проект компилируется и запускается, но ничего не появляется в окне.

Предполагается, что на нем будет отображаться текст и область с некоторыми точками. Может ли кто-нибудь помочь мне исправить это?

Вот мой код:

#include <stdio.h> 
#include <windows.h>  
#include <GL/gl.h>   
#include <glut.h>   

#define KEY_ESCAPE 27 

#define PROJECTION_WIDTH 150 
#define NUMBER_OF_FLIES 50 

float xpos[NUMBER_OF_FLIES]; 
float ypos[NUMBER_OF_FLIES]; 


typedef struct { 
    int width; 
    int height; 
    char* title; 
    float field_of_view_angle; 
    float z_near; 
    float z_far; 
} glutWindow; 

glutWindow win; 

// To display the text 
void renderBitmapString(float x, float y, void *font, const char *string) 
{ 
    const char *c; 
    glRasterPos3f(x, y, 0); 
    for (c = string; *c != '\0'; c++) 
    { 
     glutBitmapCharacter(font, *c); 
    } 
} 

void displayText() 
{ 

    glPushMatrix(); 
    //glTranslatef(1.0, 0.50, 0.5); 
     //const int font = (int)GLUT_BITMAP_9_BY_15; 
     const int font = (int)GLUT_BITMAP_HELVETICA_12; 
     glColor3f(0.0f, 0.0f, 0.0f);        // black color 
     renderBitmapString(-1.7, 1.3, (void *)font, "1. Load Measured projections"); 
     renderBitmapString(-1.7, 1.2, (void *)font, "2. Set the position of flies, i.e. create initial guess"); 
     renderBitmapString(-1.7, 1.1, (void *)font, "3. Compute projections from the current reconstruction"); 
     renderBitmapString(-1.7, 1, (void *)font, "4. Compute the population's perfomance, i.e. the global fitness"); 
     renderBitmapString(-1.7, 0.9, (void *)font, "5. Select a random fly (fly_to_kill)"); 
     renderBitmapString(-1.7, 0.8, (void *)font, "6. Remove the fly's contribution"); 
     renderBitmapString(-1.7, 0.7, (void *)font, "7. Compute the population's performance without the selected fly"); 
     renderBitmapString(-1.7, 0.6, (void *)font, "8. Compare the performances, i.e. compute the fly's local fitness"); 
     renderBitmapString(-1.7, 0.5, (void *)font, "9. If the local fitness is equal to or greater than the selection threshold,"); 
     renderBitmapString(-1.5, 0.4, (void *)font, "then go to Step 10, "); 
     renderBitmapString(-1.5, 0.3, (void *)font, "else go to Step 11"); 
     renderBitmapString(-1.7, 0.2, (void *)font, "10. Restore the fly's contribution, then go to Step 5"); 
     renderBitmapString(-1.7, 0.1, (void *)font, "11. Select a genetic operator"); 
     renderBitmapString(-1.7, 0.0, (void *)font, "12. If the genetic operator is mutation,"); 
     renderBitmapString(-1.5, -0.1, (void *)font, "then go to Step 13, "); 
     renderBitmapString(-1.5, -0.2, (void *)font, "else go to Step 19 "); 
     renderBitmapString(-1.7, -0.3, (void *)font, "13. Select a random fly (fly_to_reproduce)"); 
     renderBitmapString(-1.7, -0.4, (void *)font, "14. Remove the fly's contribution"); 
     renderBitmapString(-1.7, -0.5, (void *)font, "15. Compute the population's performance without the selected fly"); 
     renderBitmapString(-1.7, -0.6, (void *)font, "16. Compare the performances, i.e. compute the fly's local fitness"); 
     renderBitmapString(-1.7, -0.7, (void *)font, "17. Restore the fly's contribution'"); 
     renderBitmapString(-1.7, -0.8, (void *)font, "18. If the local fitness is smaller than the selection threshold,"); 
     renderBitmapString(-1.5, -0.9, (void *)font, "then go to Step 13, "); 
     renderBitmapString(-1.5, -1, (void *)font, "else go to Step 20 "); 
     renderBitmapString(-1.7, -1.1, (void *)font, "19. Replace fly_to_kill by a new fly with a random position, go to Step 22"); 
     renderBitmapString(-1.7, -1.2, (void *)font, "20. Replace fly_to_kill by a new fly based on fly_to_reproduce"); 
     renderBitmapString(-1.7, -1.3, (void *)font, "21. Add the fly's contribution to the population"); 
     renderBitmapString(-1.7, -1.4, (void *)font, "22. If stop the reconstruction,"); 
     renderBitmapString(-1.5, -1.5, (void *)font, "then go to Step 23, "); 
     renderBitmapString(-1.5, -1.6, (void *)font, "else go to Step 4 "); 
     renderBitmapString(-1.7, -1.7, (void *)font, "23. Extract good flies"); 

     // the bottom left 
     renderBitmapString(-3.9, -0.9, (void *)font, "Iterative paradigm for tomography reconstruction"); 
     renderBitmapString(-3.9, -1, (void *)font, "(click here to view the flowchart in full resolution)"); 
     // the top right 
     renderBitmapString(1.8, 1.3, (void *)font, "Basic Fly algorithm for tomography reconstruction"); 
     renderBitmapString(1.8, 1.2, (void *)font, "(click here to view the flowchart in full resolution)"); 

    glPopMatrix(); 
    glutSwapBuffers(); 
} 

void displayFlies() 
{ 
    glPushMatrix(); 
     //glTranslatef(0.0, 0.50, 0.0); 
     glColor3f(0.0f, 0.0f, 1.0f);  //blue color 

     glPushAttrib(GL_POINT_BIT); 
      glPointSize(5.0); 

      // drawing the data 
      for (int i = 0; i < NUMBER_OF_FLIES; i++){ 
       int DX = xpos[i]; 
       int DY = ypos[i]; 
       glPushMatrix(); 
        //glTranslatef(- 0.85 + DX * 0.014, -1.2 + DY * 0.0135, 0.0); 

        glBegin(GL_POINTS); // drawing points 
        glVertex3f(DX, DY, 0.0f); 
        glEnd(); 

       glPopMatrix(); 
      } 

     glPopAttrib(); 

     // draw The display Area 
     glBegin(GL_LINE_LOOP);    //start drawing a line loop 
     glVertex3f(0.65f, 0.25f, 0.0f); //left of window 
     glVertex3f(0.65f, -1.20f, 0.0f); //bottom of window 
     glVertex3f(-0.85f, -1.20f, 0.0f); //right of window 
     glVertex3f(-0.85f, 0.25f, 0.0f); //top of window 
     glEnd();       //end drawing of line loop 
    glPopMatrix(); 
    glutSwapBuffers(); 
} 

void displayProjection() 
{ 
    glPushMatrix(); 
    //glTranslatef(1.20, 0.50, 0.0); 

     // The upper rectangle 
     glBegin(GL_LINE_LOOP);    //start drawing a line loop 
     glVertex3f(0.65f, 0.60f, 0.0f); //left of window 
     glVertex3f(0.65f, 0.27f, 0.0f); //bottom of window 
     glVertex3f(-0.85f, 0.27f, 0.0f); //right of window 
     glVertex3f(-0.85f, 0.60f, 0.0f); //top of window 
     glEnd(); 

     //The right rectangle 
     glBegin(GL_LINE_LOOP);    //start drawing a line loop 
     glVertex3f(0.67f, 0.25f, 0.0f); //left of window 
     glVertex3f(0.67f, -1.20f, 0.0f); //bottom of window 
     glVertex3f(0.99f, -1.20f, 0.0f); //right of window 
     glVertex3f(0.99f, 0.25f, 0.0f); //top of window 
     glEnd();       //end drawing of line loop 

     // draw Horizontal RED lines 
     glBegin(GL_LINES); 
     glColor3f(1.0f, 0.0f, 0.0f); 
     glVertex3f(-0.25f, 0.60f, 0.0f); 
     glVertex3f(-0.25f, 0.27f, 0.0f); 
     glVertex3f(0.1f, 0.27f, 0.0f); 
     glVertex3f(0.1f, 0.60f, 0.0f); 
     glEnd(); 

     // draw Upper RED lines 
     glBegin(GL_LINES); 
     glVertex3f(0.46f, 0.18f, 0.59f); // origin of the Right line 
     glVertex3f(0.59f, 0.29f, -0.11f); // ending point of the Right line 

     glVertex3f(-0.37f, 0.18f, 0.59f); // origin of the Left line 
     glVertex3f(-0.33f, 0.29f, -0.11f); // ending point of the Left line 

     glVertex3f(0.37f, 0.40f, 0.92f); // origin of the Upper line 
     glVertex3f(0.40f, 0.49f, 0.50f); // ending point of the Upper line 
     glEnd(); 


     // draw Horizontal RED lines 
     glBegin(GL_LINES); 
     glVertex3f(-0.06f, 0.47f, -1.50f); // Origin The Upper Horizontal line 
     glVertex3f(-0.06f, -0.23f, -1.50f); // Ending point of The Upper Horizontal line 

     glVertex3f(-0.06f, -0.63f, -1.50f); // Origin The bottom Horizontal line 
     glVertex3f(-0.06f, -1.40f, -1.50f); // Ending point of The bottom Horizontal line 

     glVertex3f(0.36f, -0.23f, -1.50f); // Origin The right Horizontal line 
     glVertex3f(0.36f, -0.63f, -1.50f); // Ending point of The right Horizontal line 

     glVertex3f(0.78f, -0.30f, 0.21f); // origin of the upper vartical line 
     glVertex3f(0.95f, -0.29f, -0.11f); // ending point of the upper vartical line 

     glVertex3f(0.78f, -0.60f, 0.21f); // origin of the bottom vartical line 
     glVertex3f(0.95f, -0.61f, -0.11f); // ending point of the bottom vartical line 


     glEnd(); 

    glPopMatrix(); 

} 


// intialization function 
void initialize() 
{ 
    glMatrixMode(GL_PROJECTION);           // select projection matrix 
    glViewport(0, 0, win.width, win.height);        // set the viewport 
    glMatrixMode(GL_PROJECTION);           // set matrix mode 
    glLoadIdentity();              // reset projection matrix 
    GLfloat aspect = (GLfloat)win.width/win.height; 
    //gluPerspective(win.field_of_view_angle, aspect, win.z_near, win.z_far); // set up a perspective projection matrix 
    gluOrtho2D(0, win.width, 0, win.height); 
    glMatrixMode(GL_MODELVIEW);            // specify which matrix is the current matrix 
    glClearDepth(1.0f);              // specify the clear value for the depth buffer 
    glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);      // specify implementation-specific hints 
    glClearColor(1.0f, 1.0f, 1.0f, 1.0f);        // specify clear values for the color buffers"background" 

} 

// keyboard control function 
void keyboard(unsigned char key, int mousePositionX, int mousePositionY) 
{ 
    switch (key) 
    { 
    case KEY_ESCAPE: 
     exit(0); 
     break; 

    default: 
     break; 
    } 
} 

// the main function 
int main(int argc, char **argv) 
{ 
    // set window values 
    win.width = 1350; 
    win.height = 690; 
    win.title = " The Project "; 
    win.field_of_view_angle = 45; 
    win.z_near = 1.0f; 
    win.z_far = 500.0f; 
    //initialing the data 
    for (int i = 0; i < NUMBER_OF_FLIES; i++){ 
     xpos[i] = rand() % PROJECTION_WIDTH; 
     ypos[i] = rand() % PROJECTION_WIDTH; 
    } 
    // initialize and run program 
    glutInit(&argc, argv);          // GLUT initialization 
    glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH); // Display Mode 
    glutInitWindowSize(win.width, win.height);     // set window size 
    glutCreateWindow(win.title);        // create Window 
    glutDisplayFunc(displayText);         // register Display Function 
    glutIdleFunc(displayText);          // register Idle Function 
    glutDisplayFunc(displayFlies);         // register Display Function 
    glutIdleFunc(displayFlies); 
    glutDisplayFunc(displayProjection);         // register Display Function 
    glutIdleFunc(displayProjection); 
    glutKeyboardFunc(keyboard);         // register Keyboard Handler 
    initialize(); 
    glutMainLoop();            // run GLUT mainloop 
    return 0; 
} 

Answer 1

У вас есть три различные функции дисплея, но glutDisplayFunc и glutIdleFunc использовать только последний один вы установили, так displayText и displayFlies не используются.

Последний, displayProjection, нуждается в строку в конце:

glutSwapBuffers(); 

Кроме того, вам может понадобиться установить некоторые огни, чтобы осветить то, что вы рисуете.

Кстати, комментирование два других, вы можете проверить displayFlies, которая делает кучу синих точек, и displayText, который записывает текст (в черном на черном фоне, несколько линий друг на друга), также.

Может быть лучше попробовать некоторые учебники первым, например NeHe ... и да, как и другие комментаторы сказали, вы можете быть лучше обучение шейдеры :)