SDL3-m2/showcases/showcase_clear.mod

MODULE showcase_clear ;

(*
   m2SDL3 showcase, ported from SDL upstream
   examples/renderer/01-clear/clear.c (public domain).

   Clears the window to a smoothly fading color every frame; the
   sine-wave trick picks the color from the elapsed time.

   SDL3 native form (no SDL2 adaptation needed here):
   - SDL_CreateWindowAndRenderer(title, w, h, flags, win^, ren^).
   - SDL_SetRenderDrawColorFloat takes 0.0..1.0 SHORTREAL values.
   - Callback structure flattened into a plain main loop with
     DrainEvents; auto-quit after 8 s so it terminates unattended.
*)

FROM SYSTEM IMPORT CARDINAL8;
FROM SDL3 IMPORT SDL_Init, SDL_Quit, SDL_Delay,
   SDL_GetTicks, SDLInitVideo;
FROM SDL3Video IMPORT WindowHandle, SDL_DestroyWindow, WindowResizable;
FROM SDL3Render IMPORT RendererHandle,
   SDL_CreateWindowAndRenderer, SDL_DestroyRenderer,
   SDL_SetRenderDrawColorFloat, SDL_RenderClear, SDL_RenderPresent,
   SDL_SetRenderLogicalPresentation, LogicalLetterbox;
FROM SDL3Utils IMPORT DrainEvents;
FROM MathLib0 IMPORT sin;
FROM libc IMPORT printf;

CONST FrameMs = 16; MaxMs = 8000;

VAR
   win: WindowHandle;
   ren: RendererHandle;
   quit: BOOLEAN;
   start: LONGCARD;
   t: REAL;
   r, g, b: SHORTREAL;

BEGIN
   IF NOT SDL_Init(SDLInitVideo) THEN
      printf("showcase_clear: SDL_Init failed\n");
      HALT(1)
   END;
   IF NOT SDL_CreateWindowAndRenderer("m2SDL3 clear", 640, 480,
                                      VAL(LONGCARD, WindowResizable),
                                      win, ren) THEN
      printf("showcase_clear: CreateWindowAndRenderer failed\n");
      SDL_Quit;
      HALT(1)
   END;
   SDL_SetRenderLogicalPresentation(ren, 640, 480, LogicalLetterbox);

   printf("showcase_clear: fading, close window or wait 8s\n");
   quit := FALSE;
   start := SDL_GetTicks();
   WHILE NOT quit DO
      DrainEvents(quit);
      (* seconds since start, as REAL (double). *)
      t := LFLOAT(SDL_GetTicks()) / 1000.0;
      r := VAL(SHORTREAL, 0.5 + 0.5 * sin(t));
      g := VAL(SHORTREAL, 0.5 + 0.5 * sin(t + 2.0944));
      b := VAL(SHORTREAL, 0.5 + 0.5 * sin(t + 4.1888));
      SDL_SetRenderDrawColorFloat(ren, r, g, b, VAL(SHORTREAL, 1.0));
      SDL_RenderClear(ren);
      SDL_RenderPresent(ren);
      IF SDL_GetTicks() - start > MaxMs THEN quit := TRUE END;
      SDL_Delay(FrameMs)
   END;

   SDL_DestroyRenderer(ren);
   SDL_DestroyWindow(win);
   SDL_Quit;
   printf("showcase_clear: bye\n")
END showcase_clear.