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