#+TITLE: sdl2 org src

#+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