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 #ifdef GL_VERSION_ES_CM_1_0
  49 #  define glOrtho glOrthof
  50 #endif
  51
  52 namespace
  53 {
  54
  55 inline void intern_draw(float left, float top, float right, float bottom,
  56                         float uv_left, float uv_top,
  57                         float uv_right, float uv_bottom,
  58                         float angle, float alpha,
  59                         const Color& color,
  60                         const Blend& blend,
  61                         DrawingEffect effect)
  62 {
  63   if(effect & HORIZONTAL_FLIP)
  64     std::swap(uv_left, uv_right);
  65
  66   if(effect & VERTICAL_FLIP)
  67     std::swap(uv_top, uv_bottom);
  68
  69   // unrotated blit
  70   glBlendFunc(blend.sfactor, blend.dfactor);
  71   glColor4f(color.red, color.green, color.blue, color.alpha * alpha);
  72
  73   if (angle == 0.0f) {
  74     float vertices[] = {
  75       left, top,
  76       right, top,
  77       right, bottom,
  78       left, bottom,
  79     };
  80     glVertexPointer(2, GL_FLOAT, 0, vertices);
  81
  82     float uvs[] = {
  83       uv_left, uv_top,
  84       uv_right, uv_top,
  85       uv_right, uv_bottom,
  86       uv_left, uv_bottom,
  87     };
  88     glTexCoordPointer(2, GL_FLOAT, 0, uvs);
  89
  90     glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
  91   } else {
  92     // rotated blit
  93     float center_x = (left + right) / 2;
  94     float center_y = (top + bottom) / 2;
  95
  96     float sa = sinf(angle/180.0f*M_PI);
  97     float ca = cosf(angle/180.0f*M_PI);
  98
  99     left  -= center_x;
 100     right -= center_x;
 101
 102     top    -= center_y;
 103     bottom -= center_y;
 104
 105     float vertices[] = {
 106         left*ca - top*sa + center_x, left*sa + top*ca + center_y,
 107         right*ca - top*sa + center_x, right*sa + top*ca + center_y,
 108         right*ca - bottom*sa + center_x, right*sa + bottom*ca + center_y,
 109         left*ca - bottom*sa + center_x, left*sa + bottom*ca + center_y
 110     };
 111     glVertexPointer(2, GL_FLOAT, 0, vertices);
 112
 113     float uvs[] = {
 114       uv_left, uv_top,
 115       uv_right, uv_top,
 116       uv_right, uv_bottom,
 117       uv_left, uv_bottom,
 118     };
 119     glTexCoordPointer(2, GL_FLOAT, 0, uvs);
 120
 121     glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
 122   }
 123
 124   // FIXME: find a better way to restore the blend mode
 125   glColor4f(1.0f, 1.0f, 1.0f, 1.0f);
 126   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 127 }
 128
 129 }
 130
 131 namespace GL {
 132
 133 Renderer::Renderer()
 134   : desktop_width(-1),
 135     desktop_height(-1)
 136 {
 137   ::Renderer::instance_ = this;
 138
 139 #if SDL_MAJOR_VERSION > 1 || SDL_MINOR_VERSION > 2 || (SDL_MINOR_VERSION == 2 && SDL_PATCHLEVEL >= 10)
 140   // unfortunately only newer SDLs have these infos.
 141   // This must be called before SDL_SetVideoMode() or it will return
 142   // the window size instead of the desktop size.
 143   const SDL_VideoInfo *info = SDL_GetVideoInfo();
 144   if (info)
 145     {
 146       desktop_width  = info->current_w;
 147       desktop_height = info->current_h;
 148     }
 149 #endif
 150
 151   if(texture_manager != 0)
 152     texture_manager->save_textures();
 153
 154 #ifndef GP2X
 155   //FIXME: This is not supported on the GP2X
 156   if(config->try_vsync) {
 157     /* we want vsync for smooth scrolling */
 158     SDL_GL_SetAttribute(SDL_GL_SWAP_CONTROL, 1);
 159   }
 160 #endif
 161
 162   SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
 163
 164   // FIXME: Hu? 16bit rendering?
 165   SDL_GL_SetAttribute(SDL_GL_RED_SIZE,   5);
 166   SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 5);
 167   SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE,  5);
 168
 169   int flags = SDL_OPENGL;
 170   int width;
 171   int height;
 172
 173   if(config->use_fullscreen)
 174     {
 175       flags |= SDL_FULLSCREEN;
 176       width  = config->fullscreen_width;
 177       height = config->fullscreen_height;
 178     }
 179   else
 180     {
 181       flags |= SDL_RESIZABLE;
 182       width  = config->window_width;
 183       height = config->window_height;
 184     }
 185
 186   int bpp = 0;
 187   SDL_Surface *screen = SDL_SetVideoMode(width, height, bpp, flags);
 188
 189   if(screen == 0) {
 190     std::stringstream msg;
 191     msg << "Couldn't set video mode (" << width << "x" << height
 192         << "-" << bpp << "bpp): " << SDL_GetError();
 193     throw std::runtime_error(msg.str());
 194   }
 195
 196   // setup opengl state and transform
 197   glDisable(GL_DEPTH_TEST);
 198   glDisable(GL_CULL_FACE);
 199   glEnable(GL_TEXTURE_2D);
 200   glEnable(GL_BLEND);
 201   glEnableClientState(GL_VERTEX_ARRAY);
 202   glEnableClientState(GL_TEXTURE_COORD_ARRAY);
 203   glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 204
 205   // Init the projection matrix, viewport and stuff
 206   apply_config();
 207
 208   if(texture_manager == 0)
 209     texture_manager = new TextureManager();
 210   else
 211     texture_manager->reload_textures();
 212 }
 213
 214 Renderer::~Renderer()
 215 {
 216 }
 217
 218 void
 219 Renderer::draw_surface(const DrawingRequest& request)
 220 {
 221   const Surface* surface = (const Surface*) request.request_data;
 222   GL::Texture *gltexture = dynamic_cast<GL::Texture *>(surface->get_texture());
 223   GL::SurfaceData *surface_data = reinterpret_cast<GL::SurfaceData *>(surface->get_surface_data());
 224
 225   glBindTexture(GL_TEXTURE_2D, gltexture->get_handle());
 226   intern_draw(request.pos.x, request.pos.y,
 227               request.pos.x + surface->get_width(),
 228               request.pos.y + surface->get_height(),
 229               surface_data->get_uv_left(),
 230               surface_data->get_uv_top(),
 231               surface_data->get_uv_right(),
 232               surface_data->get_uv_bottom(),
 233               request.angle,
 234               request.alpha,
 235               request.color,
 236               request.blend,
 237               request.drawing_effect);
 238 }
 239
 240 void
 241 Renderer::draw_surface_part(const DrawingRequest& request)
 242 {
 243   const SurfacePartRequest* surfacepartrequest
 244     = (SurfacePartRequest*) request.request_data;
 245   const Surface *surface = surfacepartrequest->surface;
 246   GL::Texture *gltexture = dynamic_cast<GL::Texture *>(surface->get_texture());
 247   GL::SurfaceData *surface_data = reinterpret_cast<GL::SurfaceData *>(surface->get_surface_data());
 248
 249   float uv_width = surface_data->get_uv_right() - surface_data->get_uv_left();
 250   float uv_height = surface_data->get_uv_bottom() - surface_data->get_uv_top();
 251
 252   float uv_left = surface_data->get_uv_left() + (uv_width * surfacepartrequest->source.x) / surface->get_width();
 253   float uv_top = surface_data->get_uv_top() + (uv_height * surfacepartrequest->source.y) / surface->get_height();
 254   float uv_right = surface_data->get_uv_left() + (uv_width * (surfacepartrequest->source.x + surfacepartrequest->size.x)) / surface->get_width();
 255   float uv_bottom = surface_data->get_uv_top() + (uv_height * (surfacepartrequest->source.y + surfacepartrequest->size.y)) / surface->get_height();
 256
 257   glBindTexture(GL_TEXTURE_2D, gltexture->get_handle());
 258   intern_draw(request.pos.x, request.pos.y,
 259               request.pos.x + surfacepartrequest->size.x,
 260               request.pos.y + surfacepartrequest->size.y,
 261               uv_left,
 262               uv_top,
 263               uv_right,
 264               uv_bottom,
 265               0.0,
 266               request.alpha,
 267               Color(1.0, 1.0, 1.0),
 268               Blend(),
 269               request.drawing_effect);
 270 }
 271
 272 void
 273 Renderer::draw_gradient(const DrawingRequest& request)
 274 {
 275   const GradientRequest* gradientrequest
 276     = (GradientRequest*) request.request_data;
 277   const Color& top = gradientrequest->top;
 278   const Color& bottom = gradientrequest->bottom;
 279
 280   glDisable(GL_TEXTURE_2D);
 281   glDisableClientState(GL_TEXTURE_COORD_ARRAY);
 282   glEnableClientState(GL_COLOR_ARRAY);
 283
 284   float vertices[] = {
 285     0, 0,
 286     SCREEN_WIDTH, 0,
 287     SCREEN_WIDTH, SCREEN_HEIGHT,
 288     0, SCREEN_HEIGHT
 289   };
 290   glVertexPointer(2, GL_FLOAT, 0, vertices);
 291
 292   float colors[] = {
 293     top.red, top.green, top.blue, top.alpha,
 294     top.red, top.green, top.blue, top.alpha,
 295     bottom.red, bottom.green, bottom.blue, bottom.alpha,
 296     bottom.red, bottom.green, bottom.blue, bottom.alpha,
 297   };
 298   glColorPointer(4, GL_FLOAT, 0, colors);
 299
 300   glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
 301
 302   glDisableClientState(GL_COLOR_ARRAY);
 303   glEnableClientState(GL_TEXTURE_COORD_ARRAY);
 304
 305   glEnable(GL_TEXTURE_2D);
 306   glColor4f(1, 1, 1, 1);
 307 }
 308
 309 void
 310 Renderer::draw_filled_rect(const DrawingRequest& request)
 311 {
 312   const FillRectRequest* fillrectrequest
 313     = (FillRectRequest*) request.request_data;
 314
 315   glDisable(GL_TEXTURE_2D);
 316   glColor4f(fillrectrequest->color.red, fillrectrequest->color.green,
 317             fillrectrequest->color.blue, fillrectrequest->color.alpha);
 318   glDisableClientState(GL_TEXTURE_COORD_ARRAY);
 319
 320   if (fillrectrequest->radius != 0.0f)
 321     {
 322       // draw round rect
 323       // Keep radius in the limits, so that we get a circle instead of
 324       // just graphic junk
 325       float radius = std::min(fillrectrequest->radius,
 326                               std::min(fillrectrequest->size.x/2,
 327                                        fillrectrequest->size.y/2));
 328
 329       // inner rectangle
 330       Rect irect(request.pos.x    + radius,
 331                  request.pos.y    + radius,
 332                  request.pos.x + fillrectrequest->size.x - radius,
 333                  request.pos.y + fillrectrequest->size.y - radius);
 334
 335
 336       int n = 8;
 337       int p = 0;
 338       float vertices[(n+1) * 4 * 2];
 339
 340       for(int i = 0; i <= n; ++i)
 341         {
 342           float x = sinf(i * (M_PI/2) / n) * radius;
 343           float y = cosf(i * (M_PI/2) / n) * radius;
 344
 345           vertices[p++] = irect.get_left() - x;
 346           vertices[p++] = irect.get_top()  - y;
 347
 348           vertices[p++] = irect.get_right() + x;
 349           vertices[p++] = irect.get_top()   - y;
 350         }
 351
 352       for(int i = 0; i <= n; ++i)
 353         {
 354           float x = cosf(i * (M_PI/2) / n) * radius;
 355           float y = sinf(i * (M_PI/2) / n) * radius;
 356
 357           vertices[p++] = irect.get_left()   - x;
 358           vertices[p++] = irect.get_bottom() + y;
 359
 360           vertices[p++] = irect.get_right()  + x;
 361           vertices[p++] = irect.get_bottom() + y;
 362         }
 363
 364       glVertexPointer(2, GL_FLOAT, 0, vertices);
 365       glDrawArrays(GL_TRIANGLE_STRIP, 0,  sizeof(vertices)/sizeof(float)/2);
 366     }
 367   else
 368     {
 369       float x = request.pos.x;
 370       float y = request.pos.y;
 371       float w = fillrectrequest->size.x;
 372       float h = fillrectrequest->size.y;
 373
 374       float vertices[] = {
 375         x,   y,
 376         x+w, y,
 377         x+w, y+h,
 378         x,   y+h
 379       };
 380       glVertexPointer(2, GL_FLOAT, 0, vertices);
 381
 382       glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
 383     }
 384
 385   glEnableClientState(GL_TEXTURE_COORD_ARRAY);
 386   glEnable(GL_TEXTURE_2D);
 387   glColor4f(1, 1, 1, 1);
 388 }
 389
 390 void
 391 Renderer::draw_inverse_ellipse(const DrawingRequest& request)
 392 {
 393   const InverseEllipseRequest* ellipse = (InverseEllipseRequest*)request.request_data;
 394
 395   glDisable(GL_TEXTURE_2D);
 396   glColor4f(ellipse->color.red,  ellipse->color.green,
 397             ellipse->color.blue, ellipse->color.alpha);
 398
 399   float x = request.pos.x;
 400   float y = request.pos.y;
 401   float w = ellipse->size.x/2.0f;
 402   float h = ellipse->size.y/2.0f;
 403
 404   static const int slices = 16;
 405   static const int points = (slices+1) * 12;
 406
 407   float vertices[points * 2];
 408   int   p = 0;
 409
 410   // Bottom
 411   vertices[p++] = SCREEN_WIDTH; vertices[p++] = SCREEN_HEIGHT;
 412   vertices[p++] = 0;            vertices[p++] = SCREEN_HEIGHT;
 413   vertices[p++] = x;            vertices[p++] = y+h;
 414
 415   // Top
 416   vertices[p++] = SCREEN_WIDTH; vertices[p++] = 0;
 417   vertices[p++] = 0;            vertices[p++] = 0;
 418   vertices[p++] = x;            vertices[p++] = y-h;
 419
 420   // Left
 421   vertices[p++] = SCREEN_WIDTH; vertices[p++] = 0;
 422   vertices[p++] = SCREEN_WIDTH; vertices[p++] = SCREEN_HEIGHT;
 423   vertices[p++] = x+w;          vertices[p++] = y;
 424
 425   // Right
 426   vertices[p++] = 0;            vertices[p++] = 0;
 427   vertices[p++] = 0;            vertices[p++] = SCREEN_HEIGHT;
 428   vertices[p++] = x-w;          vertices[p++] = y;
 429
 430   for(int i = 0; i < slices; ++i)
 431     {
 432       float ex1 = sinf(M_PI/2 / slices * i) * w;
 433       float ey1 = cosf(M_PI/2 / slices * i) * h;
 434
 435       float ex2 = sinf(M_PI/2 / slices * (i+1)) * w;
 436       float ey2 = cosf(M_PI/2 / slices * (i+1)) * h;
 437
 438       // Bottom/Right
 439       vertices[p++] = SCREEN_WIDTH; vertices[p++] = SCREEN_HEIGHT;
 440       vertices[p++] = x + ex1;      vertices[p++] = y + ey1;
 441       vertices[p++] = x + ex2;      vertices[p++] = y + ey2;
 442
 443       // Top/Left
 444       vertices[p++] = 0;            vertices[p++] = 0;
 445       vertices[p++] = x - ex1;      vertices[p++] = y - ey1;
 446       vertices[p++] = x - ex2;      vertices[p++] = y - ey2;
 447
 448       // Top/Right
 449       vertices[p++] = SCREEN_WIDTH; vertices[p++] = 0;
 450       vertices[p++] = x + ex1;      vertices[p++] = y - ey1;
 451       vertices[p++] = x + ex2;      vertices[p++] = y - ey2;
 452
 453       // Bottom/Left
 454       vertices[p++] = 0;            vertices[p++] = SCREEN_HEIGHT;
 455       vertices[p++] = x - ex1;      vertices[p++] = y + ey1;
 456       vertices[p++] = x - ex2;      vertices[p++] = y + ey2;
 457     }
 458
 459   glDisableClientState(GL_TEXTURE_COORD_ARRAY);
 460   glVertexPointer(2, GL_FLOAT, 0, vertices);
 461
 462   glDrawArrays(GL_TRIANGLES, 0, points);
 463
 464   glEnableClientState(GL_TEXTURE_COORD_ARRAY);
 465
 466   glEnable(GL_TEXTURE_2D);
 467   glColor4f(1, 1, 1, 1);
 468 }
 469
 470 void
 471 Renderer::do_take_screenshot()
 472 {
 473   // [Christoph] TODO: Yes, this method also takes care of the actual disk I/O. Split it?
 474
 475   SDL_Surface *shot_surf;
 476   // create surface to hold screenshot
 477 #if SDL_BYTEORDER == SDL_BIG_ENDIAN
 478   shot_surf = SDL_CreateRGBSurface(SDL_SWSURFACE, SCREEN_WIDTH, SCREEN_HEIGHT, 24, 0x00FF0000, 0x0000FF00, 0x000000FF, 0);
 479 #else
 480   shot_surf = SDL_CreateRGBSurface(SDL_SWSURFACE, SCREEN_WIDTH, SCREEN_HEIGHT, 24, 0x000000FF, 0x0000FF00, 0x00FF0000, 0);
 481 #endif
 482   if (!shot_surf) {
 483     log_warning << "Could not create RGB Surface to contain screenshot" << std::endl;
 484     return;
 485   }
 486
 487   // read pixels into array
 488   char* pixels = new char[3 * SCREEN_WIDTH * SCREEN_HEIGHT];
 489   if (!pixels) {
 490     log_warning << "Could not allocate memory to store screenshot" << std::endl;
 491     SDL_FreeSurface(shot_surf);
 492     return;
 493   }
 494   glReadPixels(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT, GL_RGB, GL_UNSIGNED_BYTE, pixels);
 495
 496   // copy array line-by-line
 497   for (int i = 0; i < SCREEN_HEIGHT; i++) {
 498     char* src = pixels + (3 * SCREEN_WIDTH * (SCREEN_HEIGHT - i - 1));
 499     if(SDL_MUSTLOCK(shot_surf))
 500       {
 501         SDL_LockSurface(shot_surf);
 502       }
 503     char* dst = ((char*)shot_surf->pixels) + i * shot_surf->pitch;
 504     memcpy(dst, src, 3 * SCREEN_WIDTH);
 505     if(SDL_MUSTLOCK(shot_surf))
 506       {
 507         SDL_UnlockSurface(shot_surf);
 508       }
 509   }
 510
 511   // free array
 512   delete[](pixels);
 513
 514   // save screenshot
 515   static const std::string writeDir = PHYSFS_getWriteDir();
 516   static const std::string dirSep = PHYSFS_getDirSeparator();
 517   static const std::string baseName = "screenshot";
 518   static const std::string fileExt = ".bmp";
 519   std::string fullFilename;
 520   for (int num = 0; num < 1000; num++) {
 521     std::ostringstream oss;
 522     oss << baseName;
 523     oss << std::setw(3) << std::setfill('0') << num;
 524     oss << fileExt;
 525     std::string fileName = oss.str();
 526     fullFilename = writeDir + dirSep + fileName;
 527     if (!PHYSFS_exists(fileName.c_str())) {
 528       SDL_SaveBMP(shot_surf, fullFilename.c_str());
 529       log_debug << "Wrote screenshot to \"" << fullFilename << "\"" << std::endl;
 530       SDL_FreeSurface(shot_surf);
 531       return;
 532     }
 533   }
 534   log_warning << "Did not save screenshot, because all files up to \"" << fullFilename << "\" already existed" << std::endl;
 535   SDL_FreeSurface(shot_surf);
 536 }
 537
 538 void
 539 Renderer::flip()
 540 {
 541   assert_gl("drawing");
 542   SDL_GL_SwapBuffers();
 543 }
 544
 545 void
 546 Renderer::resize(int w, int h)
 547 {
 548   // This causes the screen to go black, which is annoying, but seems
 549   // unavoidable with SDL at the moment
 550   SDL_SetVideoMode(w, h, 0, SDL_OPENGL | SDL_RESIZABLE);
 551
 552   config->window_width  = w;
 553   config->window_height = h;
 554
 555   apply_config();
 556 }
 557
 558 void
 559 Renderer::apply_config()
 560 {
 561   if (0)
 562     {
 563       std::cout << "Applying Config:"
 564                 << "\n  Desktop: " << desktop_width << "x" << desktop_height
 565                 << "\n  Window:  " << config->window_width << "x" << config->window_height
 566                 << "\n  FullRes: " << config->fullscreen_width << "x" << config->fullscreen_height
 567                 << "\n  Aspect:  " << config->aspect_width << ":" << config->aspect_height
 568                 << "\n  Magnif:  " << config->magnification
 569                 << std::endl;
 570     }
 571
 572   int w,h;
 573   float target_aspect = float(desktop_width) / desktop_height;
 574
 575   if (config->aspect_width != 0 && config->aspect_height != 0)
 576     target_aspect = float(config->aspect_width) / float(config->aspect_height);
 577
 578   float desktop_aspect = 4.0f / 3.0f; // random default fallback guess
 579
 580   if (desktop_width != -1 && desktop_height != -1)
 581     {
 582       desktop_aspect = float(desktop_width) / float(desktop_height);
 583     }
 584
 585   // Get the screen width
 586   if (config->use_fullscreen)
 587     {
 588       w = config->fullscreen_width;
 589       h = config->fullscreen_height;
 590       desktop_aspect = float(w) / float(h);
 591     }
 592   else
 593     {
 594       w = config->window_width;
 595       h = config->window_height;
 596     }
 597
 598   if (target_aspect > 1.0f)
 599     {
 600       SCREEN_WIDTH  = static_cast<int>(w * (target_aspect / desktop_aspect));
 601       SCREEN_HEIGHT = static_cast<int>(h);
 602     }
 603   else
 604     {
 605       SCREEN_WIDTH  = static_cast<int>(w);
 606       SCREEN_HEIGHT = static_cast<int>(h  * (target_aspect / desktop_aspect));
 607     }
 608
 609   int max_width  = 1600; // FIXME: Maybe 1920 is ok too
 610   int max_height = 1200;
 611
 612   if (config->magnification == 0.0f) // Magic value that means 'minfill'
 613     {
 614       // This scales SCREEN_WIDTH/SCREEN_HEIGHT so that they never excede
 615       // max_width/max_height
 616       if (SCREEN_WIDTH > max_width || SCREEN_HEIGHT > max_height)
 617         {
 618           float scale1  = float(max_width)/SCREEN_WIDTH;
 619           float scale2  = float(max_height)/SCREEN_HEIGHT;
 620           float scale   = (scale1 < scale2) ? scale1 : scale2;
 621           SCREEN_WIDTH  = static_cast<int>(SCREEN_WIDTH  * scale);
 622           SCREEN_HEIGHT = static_cast<int>(SCREEN_HEIGHT * scale);
 623         }
 624
 625       glViewport(0, 0, w, h);
 626     }
 627   else
 628     {
 629       SCREEN_WIDTH  = static_cast<int>(SCREEN_WIDTH  / config->magnification);
 630       SCREEN_HEIGHT = static_cast<int>(SCREEN_HEIGHT / config->magnification);
 631
 632       // This works by adding black borders around the screen to limit
 633       // SCREEN_WIDTH/SCREEN_HEIGHT to max_width/max_height
 634       int nw = w;
 635       int nh = h;
 636
 637       if (SCREEN_WIDTH > max_width)
 638         {
 639           nw = static_cast<int>((float) nw * float(max_width)/SCREEN_WIDTH);
 640           SCREEN_WIDTH = static_cast<int>(max_width);
 641         }
 642
 643       if (SCREEN_HEIGHT > max_height)
 644         {
 645           nh = static_cast<int>((float) nh * float(max_height)/SCREEN_HEIGHT);
 646           SCREEN_HEIGHT = static_cast<int>(max_height);
 647         }
 648
 649       // Clear both buffers so that we get a clean black border without junk
 650       glClear(GL_COLOR_BUFFER_BIT);
 651       SDL_GL_SwapBuffers();
 652       glClear(GL_COLOR_BUFFER_BIT);
 653       SDL_GL_SwapBuffers();
 654
 655       if (0)
 656         std::cout << (w-nw)/2 << " "
 657                   << (h-nh)/2 << " "
 658                   << nw << "x" << nh << std::endl;
 659
 660       glViewport(std::max(0, (w-nw)/2),
 661                  std::max(0, (h-nh)/2),
 662                  std::min(nw, w),
 663                  std::min(nh, h));
 664     }
 665
 666   if (0)
 667     std::cout << "  -> " << SCREEN_WIDTH << "x" << SCREEN_HEIGHT << std::endl;
 668
 669   glMatrixMode(GL_PROJECTION);
 670   glLoadIdentity();
 671
 672   glOrtho(0, SCREEN_WIDTH, SCREEN_HEIGHT, 0, -1, 1);
 673
 674   glMatrixMode(GL_MODELVIEW);
 675   glLoadIdentity();
 676   glTranslatef(0, 0, 0);
 677   check_gl_error("Setting up view matrices");
 678 }
 679
 680 } // namespace GL
 681
 682 #endif