src/video/gl_renderer.cpp

   1 //  $Id: gl_renderer.cpp 5063 2007-05-27 11:32:00Z matzeb $
   2 //
   3 //  SuperTux
   4 //  Copyright (C) 2006 Matthias Braun <matze@braunis.de>
   5 //
   6 //  This program is free software; you can redistribute it and/or
   7 //  modify it under the terms of the GNU General Public License
   8 //  as published by the Free Software Foundation; either version 2
   9 //  of the License, or (at your option) any later version.
  10 //
  11 //  This program is distributed in the hope that it will be useful,
  12 //  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 //  GNU General Public License for more details.
  15 //
  16 //  You should have received a copy of the GNU General Public License
  17 //  along with this program; if not, write to the Free Software
  18 //  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  19 #include <config.h>
  20
  21 #ifdef HAVE_OPENGL
  22
  23 #include <functional>
  24 #include <algorithm>
  25 #include <cassert>
  26 #include <math.h>
  27 #include <iostream>
  28 #include <SDL_image.h>
  29 #include <sstream>
  30 #include <iomanip>
  31 #include <physfs.h>
  32
  33 #include "glutil.hpp"
  34 #include "gl_renderer.hpp"
  35 #include "gl_texture.hpp"
  36 #include "gl_surface_data.hpp"
  37 #include "drawing_context.hpp"
  38 #include "drawing_request.hpp"
  39 #include "surface.hpp"
  40 #include "font.hpp"
  41 #include "main.hpp"
  42 #include "gameconfig.hpp"
  43 #include "texture.hpp"
  44 #include "texture_manager.hpp"
  45 #include "obstack/obstackpp.hpp"
  46 #define LIGHTMAP_DIV 5
  47
  48 namespace
  49 {
  50
  51 inline void intern_draw(float left, float top, float right, float bottom,
  52                         float uv_left, float uv_top,
  53                         float uv_right, float uv_bottom,
  54                         float angle, float alpha,
  55                         const Color& color,
  56                         const Blend& blend,
  57                         DrawingEffect effect)
  58 {
  59   if(effect & HORIZONTAL_FLIP)
  60     std::swap(uv_left, uv_right);
  61
  62   if(effect & VERTICAL_FLIP)
  63     std::swap(uv_top, uv_bottom);
  64
  65   // unrotated blit
  66   glBlendFunc(blend.sfactor, blend.dfactor);
  67   glColor4f(color.red, color.green, color.blue, color.alpha * alpha);
  68
  69   if (angle == 0.0f) {
  70     float vertices[] = {
  71       left, top,
  72       right, top,
  73       right, bottom,
  74       left, bottom,
  75     };
  76     glVertexPointer(2, GL_FLOAT, 0, vertices);
  77
  78     float uvs[] = {
  79       uv_left, uv_top,
  80       uv_right, uv_top,
  81       uv_right, uv_bottom,
  82       uv_left, uv_bottom,
  83     };
  84     glTexCoordPointer(2, GL_FLOAT, 0, uvs);
  85
  86     glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
  87   } else {
  88     // rotated blit
  89     float center_x = (left + right) / 2;
  90     float center_y = (top + bottom) / 2;
  91
  92     float sa = sinf(angle/180.0f*M_PI);
  93     float ca = cosf(angle/180.0f*M_PI);
  94
  95     left  -= center_x;
  96     right -= center_x;
  97
  98     top    -= center_y;
  99     bottom -= center_y;
 100
 101     float vertices[] = {
 102                 left*ca - top*sa + center_x, left*sa + top*ca + center_y,
 103                 right*ca - top*sa + center_x, right*sa + top*ca + center_y,
 104                 right*ca - bottom*sa + center_x, right*sa + bottom*ca + center_y,
 105                 left*ca - bottom*sa + center_x, left*sa + bottom*ca + center_y
 106         };
 107     glVertexPointer(2, GL_FLOAT, 0, vertices);
 108
 109     float uvs[] = {
 110       uv_left, uv_top,
 111       uv_right, uv_top,
 112       uv_right, uv_bottom,
 113       uv_left, uv_bottom,
 114     };
 115     glTexCoordPointer(2, GL_FLOAT, 0, uvs);
 116
 117     glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
 118   }
 119
 120   // FIXME: find a better way to restore the blend mode
 121   glColor4f(1.0f, 1.0f, 1.0f, 1.0f);
 122   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 123 }
 124
 125 }
 126
 127 namespace GL {
 128
 129 Renderer::Renderer()
 130   : desktop_width(-1),
 131     desktop_height(-1)
 132 {
 133   ::Renderer::instance_ = this;
 134
 135 #if SDL_MAJOR_VERSION > 1 || SDL_MINOR_VERSION > 2 || (SDL_MINOR_VERSION == 2 && SDL_PATCHLEVEL >= 10)
 136   // unfortunately only newer SDLs have these infos.
 137   // This must be called before SDL_SetVideoMode() or it will return
 138   // the window size instead of the desktop size.
 139   const SDL_VideoInfo *info = SDL_GetVideoInfo();
 140   if (info)
 141     {
 142       desktop_width  = info->current_w;
 143       desktop_height = info->current_h;
 144     }
 145 #endif
 146
 147   if(texture_manager != 0)
 148     texture_manager->save_textures();
 149
 150   if(config->try_vsync) {
 151     /* we want vsync for smooth scrolling */
 152     SDL_GL_SetAttribute(SDL_GL_SWAP_CONTROL, 1);
 153   }
 154
 155   SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
 156
 157   // Hu? 16bit rendering?
 158   SDL_GL_SetAttribute(SDL_GL_RED_SIZE,   5);
 159   SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 5);
 160   SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE,  5);
 161
 162   int flags = SDL_OPENGL;
 163   int width;
 164   int height;
 165   if(config->use_fullscreen)
 166     {
 167       flags |= SDL_FULLSCREEN;
 168       width  = config->fullscreen_width;
 169       height = config->fullscreen_height;
 170     }
 171   else
 172     {
 173       flags |= SDL_RESIZABLE;
 174       width  = config->window_width;
 175       height = config->window_height;
 176     }
 177   int bpp = 0;
 178
 179   SDL_Surface *screen = SDL_SetVideoMode(width, height, bpp, flags);
 180   if(screen == 0) {
 181     std::stringstream msg;
 182     msg << "Couldn't set video mode (" << width << "x" << height
 183         << "-" << bpp << "bpp): " << SDL_GetError();
 184     throw std::runtime_error(msg.str());
 185   }
 186
 187   // setup opengl state and transform
 188   glDisable(GL_DEPTH_TEST);
 189   glDisable(GL_CULL_FACE);
 190   glEnable(GL_TEXTURE_2D);
 191   glEnable(GL_BLEND);
 192   glEnable(GL_VERTEX_ARRAY);
 193   glEnable(GL_TEXTURE_COORD_ARRAY);
 194   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 195
 196   glViewport(0, 0, screen->w, screen->h);
 197   glMatrixMode(GL_PROJECTION);
 198   glLoadIdentity();
 199
 200   // logical resolution here not real monitor resolution
 201   glOrtho(0, SCREEN_WIDTH, SCREEN_HEIGHT, 0, -1.0, 1.0);
 202
 203   glMatrixMode(GL_MODELVIEW);
 204   glLoadIdentity();
 205   glTranslatef(0, 0, 0);
 206
 207   check_gl_error("Setting up view matrices");
 208
 209
 210   if(texture_manager == 0)
 211     texture_manager = new TextureManager();
 212   else
 213     texture_manager->reload_textures();
 214 }
 215
 216 Renderer::~Renderer()
 217 {
 218 }
 219
 220 void
 221 Renderer::draw_surface(const DrawingRequest& request)
 222 {
 223   const Surface* surface = (const Surface*) request.request_data;
 224   GL::Texture *gltexture = dynamic_cast<GL::Texture *>(surface->get_texture());
 225   GL::SurfaceData *surface_data = reinterpret_cast<GL::SurfaceData *>(surface->get_surface_data());
 226
 227   glBindTexture(GL_TEXTURE_2D, gltexture->get_handle());
 228   intern_draw(request.pos.x, request.pos.y,
 229               request.pos.x + surface->get_width(),
 230               request.pos.y + surface->get_height(),
 231               surface_data->get_uv_left(),
 232               surface_data->get_uv_top(),
 233               surface_data->get_uv_right(),
 234               surface_data->get_uv_bottom(),
 235               request.angle,
 236               request.alpha,
 237               request.color,
 238               request.blend,
 239               request.drawing_effect);
 240 }
 241
 242 void
 243 Renderer::draw_surface_part(const DrawingRequest& request)
 244 {
 245   const SurfacePartRequest* surfacepartrequest
 246     = (SurfacePartRequest*) request.request_data;
 247   const Surface *surface = surfacepartrequest->surface;
 248   GL::Texture *gltexture = dynamic_cast<GL::Texture *>(surface->get_texture());
 249   GL::SurfaceData *surface_data = reinterpret_cast<GL::SurfaceData *>(surface->get_surface_data());
 250
 251   float uv_width = surface_data->get_uv_right() - surface_data->get_uv_left();
 252   float uv_height = surface_data->get_uv_bottom() - surface_data->get_uv_top();
 253
 254   float uv_left = surface_data->get_uv_left() + (uv_width * surfacepartrequest->source.x) / surface->get_width();
 255   float uv_top = surface_data->get_uv_top() + (uv_height * surfacepartrequest->source.y) / surface->get_height();
 256   float uv_right = surface_data->get_uv_left() + (uv_width * (surfacepartrequest->source.x + surfacepartrequest->size.x)) / surface->get_width();
 257   float uv_bottom = surface_data->get_uv_top() + (uv_height * (surfacepartrequest->source.y + surfacepartrequest->size.y)) / surface->get_height();
 258
 259   glBindTexture(GL_TEXTURE_2D, gltexture->get_handle());
 260   intern_draw(request.pos.x, request.pos.y,
 261               request.pos.x + surfacepartrequest->size.x,
 262               request.pos.y + surfacepartrequest->size.y,
 263               uv_left,
 264               uv_top,
 265               uv_right,
 266               uv_bottom,
 267               0.0,
 268               request.alpha,
 269               Color(1.0, 1.0, 1.0),
 270               Blend(),
 271               request.drawing_effect);
 272 }
 273
 274 void
 275 Renderer::draw_gradient(const DrawingRequest& request)
 276 {
 277   const GradientRequest* gradientrequest
 278     = (GradientRequest*) request.request_data;
 279   const Color& top = gradientrequest->top;
 280   const Color& bottom = gradientrequest->bottom;
 281
 282   glDisable(GL_TEXTURE_2D);
 283   glDisable(GL_TEXTURE_COORD_ARRAY);
 284   glEnable(GL_COLOR_ARRAY);
 285
 286   float vertices[] = {
 287     0, 0,
 288     SCREEN_WIDTH, 0,
 289     SCREEN_WIDTH, SCREEN_HEIGHT,
 290     0, SCREEN_HEIGHT
 291   };
 292   glVertexPointer(2, GL_FLOAT, 0, vertices);
 293
 294   float colors[] = {
 295     top.red, top.green, top.blue, top.alpha,
 296     top.red, top.green, top.blue, top.alpha,
 297     bottom.red, bottom.green, bottom.blue, bottom.alpha,
 298     bottom.red, bottom.green, bottom.blue, bottom.alpha,
 299   };
 300   glColorPointer(4, GL_FLOAT, 0, colors);
 301
 302   glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
 303
 304   glDisable(GL_COLOR_ARRAY);
 305   glEnable(GL_TEXTURE_COORD_ARRAY);
 306
 307   glEnable(GL_TEXTURE_2D);
 308   glColor4f(1, 1, 1, 1);
 309 }
 310
 311 void
 312 Renderer::draw_filled_rect(const DrawingRequest& request)
 313 {
 314   const FillRectRequest* fillrectrequest
 315     = (FillRectRequest*) request.request_data;
 316
 317   if (fillrectrequest->radius != 0.0f)
 318     {
 319       // draw round rect
 320       // Keep radius in the limits, so that we get a circle instead of
 321       // just graphic junk
 322       float radius = std::min(fillrectrequest->radius,
 323                               std::min(fillrectrequest->size.x/2,
 324                                        fillrectrequest->size.y/2));
 325
 326       // inner rectangle
 327       Rect irect(request.pos.x    + radius,
 328                  request.pos.y    + radius,
 329                  request.pos.x + fillrectrequest->size.x - radius,
 330                  request.pos.y + fillrectrequest->size.y - radius);
 331
 332       glDisable(GL_TEXTURE_2D);
 333       glColor4f(fillrectrequest->color.red, fillrectrequest->color.green,
 334                 fillrectrequest->color.blue, fillrectrequest->color.alpha);
 335
 336
 337       int n = 8;
 338       glBegin(GL_QUAD_STRIP);
 339       for(int i = 0; i <= n; ++i)
 340         {
 341           float x = sinf(i * (M_PI/2) / n) * radius;
 342           float y = cosf(i * (M_PI/2) / n) * radius;
 343
 344           glVertex2f(irect.get_left()  - x, irect.get_top() - y);
 345           glVertex2f(irect.get_right() + x, irect.get_top() - y);
 346         }
 347       for(int i = 0; i <= n; ++i)
 348         {
 349           float x = cosf(i * (M_PI/2) / n) * radius;
 350           float y = sinf(i * (M_PI/2) / n) * radius;
 351
 352           glVertex2f(irect.get_left()  - x, irect.get_bottom() + y);
 353           glVertex2f(irect.get_right() + x, irect.get_bottom() + y);
 354         }
 355       glEnd();
 356       glEnable(GL_TEXTURE_2D);
 357       glColor4f(1, 1, 1, 1);
 358     }
 359   else
 360     {
 361       float x = request.pos.x;
 362       float y = request.pos.y;
 363       float w = fillrectrequest->size.x;
 364       float h = fillrectrequest->size.y;
 365
 366       glDisable(GL_TEXTURE_2D);
 367       glColor4f(fillrectrequest->color.red, fillrectrequest->color.green,
 368                 fillrectrequest->color.blue, fillrectrequest->color.alpha);
 369
 370       glBegin(GL_QUADS);
 371       glVertex2f(x, y);
 372       glVertex2f(x+w, y);
 373       glVertex2f(x+w, y+h);
 374       glVertex2f(x, y+h);
 375       glEnd();
 376       glEnable(GL_TEXTURE_2D);
 377       glColor4f(1, 1, 1, 1);
 378     }
 379 }
 380
 381 void
 382 Renderer::draw_inverse_ellipse(const DrawingRequest& request)
 383 {
 384   const InverseEllipseRequest* ellipse = (InverseEllipseRequest*)request.request_data;
 385
 386   glDisable(GL_TEXTURE_2D);
 387   glColor4f(ellipse->color.red,  ellipse->color.green,
 388             ellipse->color.blue, ellipse->color.alpha);
 389
 390   float x = request.pos.x;
 391   float y = request.pos.y;
 392   float w = ellipse->size.x/2.0f;
 393   float h = ellipse->size.y/2.0f;
 394
 395   static const int slices = 16;
 396   static const int points = (slices+1) * 12;
 397
 398   float vertices[points * 2];
 399   int   p = 0;
 400
 401   // Bottom
 402   vertices[p++] = SCREEN_WIDTH; vertices[p++] = SCREEN_HEIGHT;
 403   vertices[p++] = 0;            vertices[p++] = SCREEN_HEIGHT;
 404   vertices[p++] = x;            vertices[p++] = y+h;
 405
 406   // Top
 407   vertices[p++] = SCREEN_WIDTH; vertices[p++] = 0;
 408   vertices[p++] = 0;            vertices[p++] = 0;
 409   vertices[p++] = x;            vertices[p++] = y-h;
 410
 411   // Left
 412   vertices[p++] = SCREEN_WIDTH; vertices[p++] = 0;
 413   vertices[p++] = SCREEN_WIDTH; vertices[p++] = SCREEN_HEIGHT;
 414   vertices[p++] = x+w;          vertices[p++] = y;
 415
 416   // Right
 417   vertices[p++] = 0;            vertices[p++] = 0;
 418   vertices[p++] = 0;            vertices[p++] = SCREEN_HEIGHT;
 419   vertices[p++] = x-w;          vertices[p++] = y;
 420
 421   for(int i = 0; i < slices; ++i)
 422     {
 423       float ex1 = sinf(M_PI/2 / slices * i) * w;
 424       float ey1 = cosf(M_PI/2 / slices * i) * h;
 425
 426       float ex2 = sinf(M_PI/2 / slices * (i+1)) * w;
 427       float ey2 = cosf(M_PI/2 / slices * (i+1)) * h;
 428
 429       // Bottom/Right
 430       vertices[p++] = SCREEN_WIDTH; vertices[p++] = SCREEN_HEIGHT;
 431       vertices[p++] = x + ex1;      vertices[p++] = y + ey1;
 432       vertices[p++] = x + ex2;      vertices[p++] = y + ey2;
 433
 434       // Top/Left
 435       vertices[p++] = 0;            vertices[p++] = 0;
 436       vertices[p++] = x - ex1;      vertices[p++] = y - ey1;
 437       vertices[p++] = x - ex2;      vertices[p++] = y - ey2;
 438
 439       // Top/Right
 440       vertices[p++] = SCREEN_WIDTH; vertices[p++] = 0;
 441       vertices[p++] = x + ex1;      vertices[p++] = y - ey1;
 442       vertices[p++] = x + ex2;      vertices[p++] = y - ey2;
 443
 444       // Bottom/Left
 445       vertices[p++] = 0;            vertices[p++] = SCREEN_HEIGHT;
 446       vertices[p++] = x - ex1;      vertices[p++] = y + ey1;
 447       vertices[p++] = x - ex2;      vertices[p++] = y + ey2;
 448     }
 449
 450   glDisable(GL_TEXTURE_COORD_ARRAY);
 451   glVertexPointer(2, GL_FLOAT, 0, vertices);
 452
 453   glDrawArrays(GL_TRIANGLES, 0, points);
 454
 455   glEnable(GL_TEXTURE_COORD_ARRAY);
 456
 457   glEnable(GL_TEXTURE_2D);
 458   glColor4f(1, 1, 1, 1);
 459 }
 460
 461 void
 462 Renderer::do_take_screenshot()
 463 {
 464   // [Christoph] TODO: Yes, this method also takes care of the actual disk I/O. Split it?
 465
 466   SDL_Surface *shot_surf;
 467   // create surface to hold screenshot
 468 #if SDL_BYTEORDER == SDL_BIG_ENDIAN
 469   shot_surf = SDL_CreateRGBSurface(SDL_SWSURFACE, SCREEN_WIDTH, SCREEN_HEIGHT, 24, 0x00FF0000, 0x0000FF00, 0x000000FF, 0);
 470 #else
 471   shot_surf = SDL_CreateRGBSurface(SDL_SWSURFACE, SCREEN_WIDTH, SCREEN_HEIGHT, 24, 0x000000FF, 0x0000FF00, 0x00FF0000, 0);
 472 #endif
 473   if (!shot_surf) {
 474     log_warning << "Could not create RGB Surface to contain screenshot" << std::endl;
 475     return;
 476   }
 477
 478   // read pixels into array
 479   char* pixels = new char[3 * SCREEN_WIDTH * SCREEN_HEIGHT];
 480   if (!pixels) {
 481     log_warning << "Could not allocate memory to store screenshot" << std::endl;
 482     SDL_FreeSurface(shot_surf);
 483     return;
 484   }
 485   glReadPixels(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT, GL_RGB, GL_UNSIGNED_BYTE, pixels);
 486
 487   // copy array line-by-line
 488   for (int i = 0; i < SCREEN_HEIGHT; i++) {
 489     char* src = pixels + (3 * SCREEN_WIDTH * (SCREEN_HEIGHT - i - 1));
 490     if(SDL_MUSTLOCK(shot_surf))
 491       {
 492         SDL_LockSurface(shot_surf);
 493       }
 494     char* dst = ((char*)shot_surf->pixels) + i * shot_surf->pitch;
 495     memcpy(dst, src, 3 * SCREEN_WIDTH);
 496     if(SDL_MUSTLOCK(shot_surf))
 497       {
 498         SDL_UnlockSurface(shot_surf);
 499       }
 500   }
 501
 502   // free array
 503   delete[](pixels);
 504
 505   // save screenshot
 506   static const std::string writeDir = PHYSFS_getWriteDir();
 507   static const std::string dirSep = PHYSFS_getDirSeparator();
 508   static const std::string baseName = "screenshot";
 509   static const std::string fileExt = ".bmp";
 510   std::string fullFilename;
 511   for (int num = 0; num < 1000; num++) {
 512     std::ostringstream oss;
 513     oss << baseName;
 514     oss << std::setw(3) << std::setfill('0') << num;
 515     oss << fileExt;
 516     std::string fileName = oss.str();
 517     fullFilename = writeDir + dirSep + fileName;
 518     if (!PHYSFS_exists(fileName.c_str())) {
 519       SDL_SaveBMP(shot_surf, fullFilename.c_str());
 520       log_debug << "Wrote screenshot to \"" << fullFilename << "\"" << std::endl;
 521       SDL_FreeSurface(shot_surf);
 522       return;
 523     }
 524   }
 525   log_warning << "Did not save screenshot, because all files up to \"" << fullFilename << "\" already existed" << std::endl;
 526   SDL_FreeSurface(shot_surf);
 527 }
 528
 529 void
 530 Renderer::flip()
 531 {
 532   assert_gl("drawing");
 533   SDL_GL_SwapBuffers();
 534 }
 535
 536 void
 537 Renderer::resize(int w, int h)
 538 {
 539   // This causes the screen to go black, which is annoying, but seems
 540   // unavoidable with SDL at the moment
 541   SDL_SetVideoMode(w, h, 0, SDL_OPENGL | SDL_RESIZABLE);
 542
 543   config->window_width  = w;
 544   config->window_height = h;
 545
 546   apply_config();
 547 }
 548
 549 void
 550 Renderer::apply_config()
 551 {
 552   std::cout << "Applying Config:"
 553             << "\n  Desktop: " << desktop_width << "x" << desktop_height
 554             << "\n  Window:  " << config->window_width << "x" << config->window_height
 555             << "\n  FullRes: " << config->fullscreen_width << "x" << config->fullscreen_height
 556             << "\n  Aspect:  " << config->aspect_width << ":" << config->aspect_height
 557             << "\n  Magnif:  " << config->magnification
 558             << std::endl;
 559
 560   int w,h;
 561   float target_aspect  = float(config->aspect_width) / float(config->aspect_height);
 562   float desktop_aspect = 4.0f / 3.0f; // random default fallback guess
 563
 564   if (desktop_width != -1 && desktop_height != -1)
 565     {
 566       desktop_aspect = float(desktop_width) / float(desktop_height);
 567     }
 568
 569   if (config->use_fullscreen)
 570     {
 571       w = config->fullscreen_width;
 572       h = config->fullscreen_height;
 573       desktop_aspect = float(w) / float(h);
 574     }
 575   else
 576     {
 577       w = config->window_width;
 578       h = config->window_height;
 579     }
 580
 581   if (target_aspect > 1.0f)
 582     {
 583       SCREEN_WIDTH  = static_cast<int> (w * (target_aspect / desktop_aspect));
 584       SCREEN_HEIGHT = static_cast<int> (h);
 585     }
 586   else
 587     {
 588       SCREEN_WIDTH  = static_cast<int> (w);
 589       SCREEN_HEIGHT = static_cast<int> (h  * (target_aspect / desktop_aspect));
 590     }
 591
 592   SCREEN_WIDTH  = static_cast<int> ((float) SCREEN_WIDTH / config->magnification);
 593   SCREEN_HEIGHT = static_cast<int> ((float) SCREEN_HEIGHT / config->magnification);
 594
 595   int max_width  = 1600; // FIXME: Maybe 1920 is ok too
 596   int max_height = 1200;
 597
 598   if (0)
 599     {
 600       // This scales SCREEN_WIDTH/SCREEN_HEIGHT so that they never excede
 601       // max_width/max_height
 602       if (SCREEN_WIDTH > max_width || SCREEN_HEIGHT > max_height)
 603         {
 604           float scale1 = float(max_width)/SCREEN_WIDTH;
 605           float scale2 = float(max_height)/SCREEN_HEIGHT;
 606           float scale = scale1 < scale2 ? scale1 : scale2;
 607           SCREEN_WIDTH  = static_cast<int> ((float) SCREEN_WIDTH * scale);
 608           SCREEN_HEIGHT = static_cast<int> ((float) SCREEN_HEIGHT * scale);
 609         }
 610
 611       glViewport(0, 0, w, h);
 612     }
 613   else
 614     {
 615       // This works by adding black borders around the screen to limit
 616       // SCREEN_WIDTH/SCREEN_HEIGHT to max_width/max_height
 617       int nw = w;
 618       int nh = h;
 619
 620       if (SCREEN_WIDTH > max_width)
 621         {
 622           nw = static_cast<int> ((float) nw * float(max_width)/SCREEN_WIDTH);
 623           SCREEN_WIDTH = static_cast<int> (max_width);
 624         }
 625
 626       if (SCREEN_HEIGHT > max_height)
 627         {
 628           nh = static_cast<int> ((float) nh * float(max_height)/SCREEN_HEIGHT);
 629           SCREEN_HEIGHT = static_cast<int> (max_height);
 630         }
 631
 632       glClear(GL_COLOR_BUFFER_BIT);
 633
 634       std::cout << (w-nw)/2 << " "
 635                 << (h-nh)/2 << " "
 636                 << nw << "x" << nh << std::endl;
 637       glViewport(std::max(0, (w-nw)/2),
 638                  std::max(0, (h-nh)/2),
 639                  std::min(nw, w),
 640                  std::min(nh, h));
 641     }
 642
 643   std::cout << "  -> " << SCREEN_WIDTH << "x" << SCREEN_HEIGHT << std::endl;
 644
 645
 646   glMatrixMode(GL_PROJECTION);
 647   glLoadIdentity();
 648   glOrtho(0, SCREEN_WIDTH, SCREEN_HEIGHT, 0, -1.0, 1.0);
 649 }
 650
 651 } // namespace GL
 652
 653 #endif