// draw text on OpenGL for wglUseFontBitmaps
//
// Last updated: <2024/01/12 21:36:58 +0900>

#include <GL/freeglut.h>
#include <stdio.h>
#include <tchar.h>

#define WIDTH 512
#define HEIGHT 288

static int count = 0;

class GLFONT
{
public:
  HFONT Hfont;
  HDC Hdc;

  // create font
  GLFONT(LPCTSTR fontname, int size)
  {
    Hfont = CreateFont(
        size,                    // font height
        0,                       // font width
        0,                       // テキストの角度
        0,                       // Orientation
        FW_REGULAR,              // font weight
        FALSE,                   // italic
        FALSE,                   // underline
        FALSE,                   // strikeout
        ANSI_CHARSET,            // charset
        OUT_DEFAULT_PRECIS,      // OutPrecision
        CLIP_DEFAULT_PRECIS,     // ClipPrecision
        ANTIALIASED_QUALITY,     // Quality
        FIXED_PITCH | FF_MODERN, // Pitch And Family
        fontname                 // face name
    );

    Hdc = wglGetCurrentDC();
    SelectObject(Hdc, Hfont);
  }

  // draw string
  void DrawString(int x, int y, char *format, ...)
  {
    int Length = 0;
    int list = 0;

    if (format == NULL)
      return;

    Length = strlen(format);
    list = glGenLists(Length);

    for (int i = 0; i < Length; i++)
    {
      wglUseFontBitmaps(Hdc, format[i], 1, list + i);
    }

    glDisable(GL_LIGHTING);
    glRasterPos2i(x, y);

    // draw
    for (int i = 0; i < Length; i++)
    {
      glCallList(list + i);
    }

    glEnable(GL_LIGHTING);

    // delete displey list
    glDeleteLists(list, Length);

    list = 0;
    Length = 0;
  }
};

GLFONT *font;

// Draw OpenGL
void display(void)
{
  glClearColor(0.2, 0.4, 0.8, 0.0);
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

  // draw text
  glColor4f(1.0, 1.0, 1.0, 1.0); // set text color

  font->DrawString(40, 40, (char *)"Hello World");

  {
    char buf[256];
    sprintf(buf, "count %d", count);
    font->DrawString(40, 100, buf);
  }

  glutSwapBuffers();
  count++;
}

void idle(void)
{
  glutPostRedisplay(); // redraw
}

void keyboard(unsigned char key, int x, int y)
{
  switch (key)
  {
  case '\x1B':
  case 'q':
    // Exit on escape or 'q' key press
    glutLeaveMainLoop();
    // exit(EXIT_SUCCESS);
    break;
  }
}

int main(int argc, char *argv[])
{
  glutInit(&argc, argv);
  glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE);
  glutInitWindowSize(WIDTH, HEIGHT);
  // glutInitWindowPosition(100, 100);

  glutCreateWindow("Draw string");

  glutKeyboardFunc(keyboard);
  glutDisplayFunc(display);
  glutIdleFunc(idle);

  glOrtho(0, WIDTH, HEIGHT, 0, -1, 1);
  font = new GLFONT(_T("Courier New"), 24);

  glutMainLoop();
  return 0;
}