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