text: /* =========================================================================
   * Freetype GL - A C OpenGL Freetype engine
   * Platform:    Any
   * WWW:         http://code.google.com/p/freetype-gl/
   * -------------------------------------------------------------------------
   * Copyright 2011,2012 Nicolas P. Rougier. All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   *  1. Redistributions of source code must retain the above copyright notice,
   *     this list of conditions and the following disclaimer.
   *
   *  2. Redistributions in binary form must reproduce the above copyright
   *     notice, this list of conditions and the following disclaimer in the
   *     documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY NICOLAS P. ROUGIER ''AS IS'' AND ANY EXPRESS OR
   * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
   * EVENT SHALL NICOLAS P. ROUGIER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
   * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   *
   * The views and conclusions contained in the software and documentation are
   * those of the authors and should not be interpreted as representing official
   * policies, either expressed or implied, of Nicolas P. Rougier.
   * ========================================================================= */
  #include "freetype-gl.h"
  #include "vertex-buffer.h"
  
  
  // ------------------------------------------------------- typedef & struct ---
  typedef struct {
      float x, y, z;    // position
      float s, t;       // texture
      float r, g, b, a; // color
  } vertex_t;
  
  
  // ------------------------------------------------------- global variables ---
  vertex_buffer_t *buffer;
  
  
  // ---------------------------------------------------------------- display ---
  void display( void )
  {
      int viewport[4];
      glGetIntegerv( GL_VIEWPORT, viewport );
      glClearColor(1,1,1,1);
      glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
      glEnable( GL_BLEND );
      glBlendFunc( GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA );
      glEnable( GL_TEXTURE_2D );
      glColor4f(1,1,1,1);
      glPushMatrix();
      glTranslatef(5, viewport[3], 0);
      vertex_buffer_render( buffer, GL_TRIANGLES, "vtc" );
      glPopMatrix();
      glutSwapBuffers( );
  }
  
  
  // ---------------------------------------------------------------- reshape ---
  void reshape(int width, int height)
  {
      glViewport(0, 0, width, height);
      glMatrixMode(GL_PROJECTION);
      glLoadIdentity();
      glOrtho(0, width, 0, height, -1, 1);
      glMatrixMode(GL_MODELVIEW);
      glutPostRedisplay();
  }
  
  
  // --------------------------------------------------------------- keyboard ---
  void keyboard( unsigned char key, int x, int y )
  {
      if ( key == 27 )
      {
          exit( 1 );
      }
  }
  
  
  // --------------------------------------------------------------- add_text ---
  void add_text( vertex_buffer_t * buffer, texture_font_t * font,
                 wchar_t * text, vec4 * color, vec2 * pen )
  {
      size_t i;
      float r = color->red, g = color->green, b = color->blue, a = color->alpha;
      for( i=0; i<wcslen(text); ++i )
      {
          texture_glyph_t *glyph = texture_font_get_glyph( font, text[i] );
          if( glyph != NULL )
          {
              int kerning = 0;
              if( i > 0)
              {
                  kerning = texture_glyph_get_kerning( glyph, text[i-1] );
              }
              pen->x += kerning;
              int x0  = (int)( pen->x + glyph->offset_x );
              int y0  = (int)( pen->y + glyph->offset_y );
              int x1  = (int)( x0 + glyph->width );
              int y1  = (int)( y0 - glyph->height );
              float s0 = glyph->s0;
              float t0 = glyph->t0;
              float s1 = glyph->s1;
              float t1 = glyph->t1;
              GLuint index = buffer->vertices->size;
              GLuint indices[] = {index, index+1, index+2,
                                  index, index+2, index+3};
              vertex_t vertices[] = { { x0,y0,0,  s0,t0,  r,g,b,a },
                                      { x0,y1,0,  s0,t1,  r,g,b,a },
                                      { x1,y1,0,  s1,t1,  r,g,b,a },
                                      { x1,y0,0,  s1,t0,  r,g,b,a } };
              vertex_buffer_push_back_indices( buffer, indices, 6 );
              vertex_buffer_push_back_vertices( buffer, vertices, 4 );
              pen->x += glyph->advance_x;
          }
      }
  }
  
  
  // ------------------------------------------------------------------- main ---
  int main( int argc, char **argv )
  {
      glutInit( &argc, argv );
      glutInitWindowSize( 800, 400 );
      glutInitDisplayMode( GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH );
      glutCreateWindow( "Freetype OpenGL / vertex arrays" );
      glutReshapeFunc( reshape );
      glutDisplayFunc( display );
      glutKeyboardFunc( keyboard );
  
      size_t i;
      texture_font_t *font = 0;
      texture_atlas_t *atlas = texture_atlas_new( 512, 512, 1 );
      const char * filename = "./Vera.ttf";
      wchar_t *text = L"A Quick Brown Fox Jumps Over The Lazy Dog 0123456789";
      buffer = vertex_buffer_new( "v3f:t2f:c4f" ); 
      vec2 pen = {{0,0}};
      vec4 black = {{0,0,0,1}};
  
      for( i=7; i < 27; ++i)
      {
          font = texture_font_new( atlas, filename, i );
          pen.x = 0;
          pen.y -= font->height;
          texture_font_load_glyphs( font, text );
          add_text( buffer, font, text, &black, &pen );
          texture_font_delete( font );
      }
  
      glBindTexture( GL_TEXTURE_2D, atlas->id );
      glutMainLoop( );
      return 0;
  }
  