api to skip frames

[yamt]

for games, it's often more important to provide a constant game speed than drawing every single frames.
it would be nicer for wasm4 to provide a mechanism for skipping frames.
especially for graphics-heavy games on slow hardware.

eg. a simple timestamp (maybe in fps) on the shared memory area.

static unsigned int n = 0;

update()
{
  if (TIMESTAMP > n++) {
    /* somehow reduce computation for this frame */
  }
}

[JerwuQu]

You could set the SYSTEM_PRESERVE_FRAMEBUFFER flag in SYSTEM_FLAGS and then skip drawing depending on frame number.

Example drawing at 30fps:

#include "wasm4.h"

const size_t FRAME_SKIP = 2; // Draw every 2nd frame

void start() {
    *SYSTEM_FLAGS |= SYSTEM_PRESERVE_FRAMEBUFFER;
}

size_t frame = 0;
void update() {
    frame++;
    if ((frame % FRAME_SKIP) == 0) {
        // Regular processing here
        rect(10, 10, 32, 32);
    }
}