#+TITLE: sdl2 org src
#+AUTHOR: screwtape
* Rich media sdl2 C applications
(skip past window settings in your reading; they are just better at the top)
** Various updates
  Now has odd inline
  | SDL_HasIntersection(SDL_Rect *, SDL_Rect *)                             |
  | SDL_IntersectRectAndLine(SDL_Rect *, int *x0, int *y0, int *x1, int *y1 |
  | Array of SDL_Rect rocks being used somehow                              |
  Note that SDL_IntersectRectAndLine clobbers intersected endpoint int *s.
  both intersections should be compared with SDL_TRUE / SDL_FALSE.
** Window settings
#+NAME: w-sizing
#+HEADER: :includes "/usr/local/include/SDL2/SDL.h"
#+begin_src C
SDL_WINDOW_RESIZABLE
#+end_src

#+NAME: w-height
#+begin_src C
768
#+end_src

#+NAME: w-width
#+begin_src C
1280
#+end_src

** template
#+BEGIN_EXAMPLE
 This template does seem a little bit  goto cleanup rather than some clunky
 long, but that is because it handles  quit flag;  but then,  it was easier
 keyboard  and mouse events and mouse  to goto quit which gotos cleanup. At
 position  in the general case.  I do  least the loop isn't goto based!
#+END_EXAMPLE
includes and libs might need to be customized. I found that  my  sdl2-config
flags on arm64 openbsd didn't actually work!
#+name: template
#+HEADER: :includes "/usr/local/include/SDL2/SDL.h" <stdlib.h>
#+HEADER: :libs "-L/usr/local/lib -lSDL2"
#+HEADER: :exports code
#+HEADER: :results none
#+HEADER: :noweb yes
#+begin_src C

 <<hero-init>>

 /* random */
 int ra, rb;
 time_t rt;
 srand((unsigned)time(&rt));
 /* /rand */

 /* Some rocks */
 int NROCKS = 2;
 int r;

 struct SDL_Rect rocks[NROCKS];
 rocks[0].x = 100; rocks[0].y = 120;
 rocks[0].w = 50; rocks[0].h = 40;

 rocks[1].x = 200; rocks[1].y = 220;
 rocks[1].w = 50; rocks[1].h = 40;



 /* Sort of clock */
 int cycle_limit = 10000;
 int cycle_now = 0;


 /* spinning animation */
 int ticks = 0;
 int tox, toy, centerx, centery;
 float xoff=0.0, yoff=0.0, l;

 int hitx, hity, hitcx, hitcy;

 centerx = 635; centery = 384; l = 100.0;
 /*/spinning animation */

 <<sdlstart>>

 for(;;){
   while(SDL_PollEvent(&e))
     if (e.type == SDL_QUIT)
     quit:
       goto cleanup;
     else if (e.type == SDL_MOUSEBUTTONDOWN)
       switch (1){
       default:
         break;
       }
     else if (e.type == SDL_MOUSEBUTTONUP)
       switch (1){
       default:
         break;
       }
     else if (e.type == SDL_KEYDOWN)
       switch (e.key.keysym.sym){
       case SDLK_UP:
         if (hero.alive == 1)
           hero.rect.y -= 10;
         for (r=0;r<NROCKS; r++)
           if (SDL_TRUE == SDL_HasIntersection(&(hero.rect),&(rocks[r])))
             hero.rect.y += 10;
         break;
       case SDLK_RIGHT:
         if (hero.alive == 1)
           hero.rect.x += 10;
         break;
       case SDLK_DOWN:
         if (hero.alive == 1)
           hero.rect.y += 10;
         break;
       case SDLK_LEFT:
         if (hero.alive == 1)
           hero.rect.x -= 10;
         break;
       case SDLK_r:
         hero.rect.x = rand() % 1000;
         hero.rect.y = rand() % 500;
         hero.alive = 1;
         break;
       case SDLK_q:
         goto quit;
       default:
         break;
       }
     else if (e.type == SDL_KEYUP)
       switch (1){
       default:
         break;
       }

   mdown = SDL_GetMouseState(&mx, &my);

   SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
   SDL_RenderClear(renderer);

   <<hero-update>>

       SDL_SetRenderDrawColor(renderer, 100, 200, 200, 255);


   /* spinning animation */
   ticks++;

   xoff= l * SDL_sin((float)ticks / (2.0 * M_PI));
   tox = centerx + (int)xoff;
   yoff= l * SDL_cos((float)ticks / (2.0 * M_PI));
   toy = centery + (int)yoff;

   SDL_RenderDrawLine(renderer, centerx, centery, tox, toy);
   /*/spinning animation */

   /* Potentially kill hero */
   hitcx = centerx; hitcy = centery;
   hitx = tox; hity = toy;
   if (hero.alive== 1 &&
       SDL_IntersectRectAndLine(&(hero.rect),
                                &hitcx, &hitcy,
                                &hitx, &hity)
       == SDL_TRUE)
     hero.alive=0;
   /* Potentially killed hero */

 /* Draw rocks */
   SDL_SetRenderDrawColor(renderer, 50, 50, 50, 255);
 for (r=0; r<NROCKS; r++)
   SDL_RenderFillRect(renderer, &rocks[r]);
 /* Drawn rocks */


   SDL_RenderPresent(renderer);
   SDL_Delay(25);

   if ((cycle_now+=25) < cycle_limit) {
     if (cycle_now < (cycle_limit / 2)) centerx--;
     else centerx++;
   } else {
     cycle_now = 0;
   }
  }
 cleanup:
 <<sdlcleanup>>
#+end_src

** My macros
*** Hero
**** Hero init
#+name: hero-init
#+begin_src C
 struct hero{
   int xpos, ypos, width, height, r, g, b, a, speed, alive;
   SDL_Rect rect;
 } hero;

   SDL_Event e;
   int mx, my;
   Uint32 mdown;

 hero.alive = 1;
 hero.rect.x=100; hero.rect.y=200; hero.rect.w=50; hero.rect.h=60;

 hero.r = 30; hero.g = 60; hero.b = 90; hero.a = 255;
 hero.speed = 10;
#+end_src

**** Hero update
#+name: hero-update
#+begin_src C
 if(hero.alive == 1)
   SDL_SetRenderDrawColor(renderer, hero.r, hero.g, hero.b, hero.a);
  else
    SDL_SetRenderDrawColor(renderer, 255, 0, 0, hero.a);
 SDL_RenderFillRect(renderer, &(hero.rect));
#+end_src


** Simple SDL2, window, renderer init
#+NAME: sdlstart
#+HEADER: :noweb yes
#+begin_src C
 SDL_Window *window;
 SDL_Renderer *renderer;

 if (SDL_Init(SDL_INIT_VIDEO) < 0){
   SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to init SDL: %s",
                SDL_GetError());
   return 3;
  }

 if (SDL_CreateWindowAndRenderer(<<w-width>>, <<w-height>>,
                                 <<w-sizing>>, &window, &renderer)){
   SDL_LogError(SDL_LOG_CATEGORY_APPLICATION, "Failed to create renderer and window: %s",
                SDL_GetError());
   return 3;
  }
#+end_src

** Simple SDL2 cleanup
#+NAME: sdlcleanup
#+begin_src C
 SDL_DestroyRenderer(renderer);
 SDL_DestroyWindow(window);
 SDL_Quit();
 return 0;
#+end_src