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/*
* Copyright (C) 2024 - Vito Caputo - <vcaputo@pengaru.com>
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published
* by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdint.h>
#include "til.h"
#include "til_fb.h"
#include "til_module_context.h"
/* This implements a "droste effect", also known as an infinity mirror:
* https://en.wikipedia.org/wiki/Droste_effect
* https://en.wikipedia.org/wiki/Infinity_mirror
*/
/* Some potential TODO items:
*
* - A default base layer so we can clear the experimental flag
*
* - Fractional, or at least runtime-configurable scaling... though
* exposing a tap for it would be fun
*
* - Runtime-configurable multisampled scaling
*
* - The current implementation is very simple but relies on the
* preservation of original contents in til_fb_fragment_snapshot(),
* which causes a full copy. This is wasteful since we only want
* the unzoomed periphery preserved from the original. Maybe there
* should be a clip mask for the preservation in
* til_fb_fragment_snapshot(), or just do the peripheral copy ourselves
* and stop asking the snapshot code to do that for us.
*
*/
typedef struct droste_context_t {
til_module_context_t til_module_context;
til_fb_fragment_t *snapshot;
} droste_context_t;
static til_module_context_t * droste_create_context(const til_module_t *module, til_stream_t *stream, unsigned seed, unsigned ticks, unsigned n_cpus, til_setup_t *setup)
{
droste_context_t *ctxt;
ctxt = til_module_context_new(module, sizeof(droste_context_t), stream, seed, ticks, n_cpus, setup);
if (!ctxt)
return NULL;
return &ctxt->til_module_context;
}
static void droste_destroy_context(til_module_context_t *context)
{
droste_context_t *ctxt = (droste_context_t *)context;
if (ctxt->snapshot)
ctxt->snapshot = til_fb_fragment_reclaim(ctxt->snapshot);
free(context);
}
/* derived from til_fragmenter_slice_per_cpu_x16(), but tweaked to only fragment the inset area */
static int droste_fragmenter(til_module_context_t *context, const til_fb_fragment_t *fragment, unsigned number, til_fb_fragment_t *res_fragment)
{
til_fb_fragment_t inset = *fragment;
unsigned slice, yoff;
assert(fragment);
assert(res_fragment);
inset.width = fragment->width >> 1;
inset.height = fragment->height >> 1;
inset.frame_width = inset.width;
inset.frame_height = inset.height;
inset.x = inset.y = 0;
inset.buf += inset.pitch * ((fragment->height - inset.height) >> 1) + ((fragment->width - inset.width) >> 1);
inset.stride += fragment->width >> 1;
slice = MAX(inset.height / context->n_cpus * 16, 1);
yoff = slice * number;
if (yoff >= inset.height)
return 0;
if (fragment->texture) {
til_fb_fragment_t inset_texture;
inset_texture = *(fragment->texture);
inset.texture = &inset_texture;
/* TODO */
assert(res_fragment->texture);
assert(fragment->frame_width == fragment->texture->frame_width);
assert(fragment->frame_height == fragment->texture->frame_height);
assert(fragment->width == fragment->texture->width);
assert(fragment->height == fragment->texture->height);
assert(fragment->x == fragment->texture->x);
assert(fragment->y == fragment->texture->y);
*(res_fragment->texture) = (til_fb_fragment_t){
.buf = fragment->texture->buf + yoff * fragment->texture->pitch,
.x = fragment->x,
.y = fragment->y + yoff,
.width = fragment->width,
.height = MIN(fragment->height - yoff, slice),
.frame_width = fragment->frame_width,
.frame_height = fragment->frame_height,
.stride = fragment->texture->stride,
.pitch = fragment->texture->pitch,
.cleared = fragment->texture->cleared,
};
}
*res_fragment = (til_fb_fragment_t){
.texture = inset.texture ? res_fragment->texture : NULL,
.buf = inset.buf + yoff * inset.pitch,
.x = inset.x,
.y = inset.y + yoff,
.width = inset.width,
.height = MIN(inset.height - yoff, slice),
.frame_width = inset.frame_width,
.frame_height = inset.frame_height,
.stride = inset.stride,
.pitch = inset.pitch,
.number = number,
.cleared = inset.cleared,
};
return 1;
}
/* Prepare a frame for concurrent drawing of fragment using multiple fragments */
static void droste_prepare_frame(til_module_context_t *context, til_stream_t *stream, unsigned ticks, til_fb_fragment_t **fragment_ptr, til_frame_plan_t *res_frame_plan)
{
*res_frame_plan = (til_frame_plan_t){ .fragmenter = droste_fragmenter };
{
droste_context_t *ctxt = (droste_context_t *)context;
til_fb_fragment_t *fragment = *fragment_ptr;
til_fb_fragment_t *snapshot = ctxt->snapshot;
if (!snapshot)
return;
if (fragment->frame_width != snapshot->frame_width ||
fragment->frame_height != snapshot->frame_height ||
fragment->height != snapshot->height ||
fragment->width != snapshot->width) {
/* discard the snapshot which will prevent doing anything this frame,
* since it doesn't match the incoming fragment (like a resize situation)
*/
ctxt->snapshot = til_fb_fragment_reclaim(ctxt->snapshot);
return;
}
/* TODO: if we're not used as an overlay, here'd be a good place to generate something or
* just use another module as a base layer... until we do something sensible here, we should
* keep this as an experimental module so it doesn't get used by automation as a base layer..
* it also needs something to show in montage.
*/
}
}
static void droste_render_fragment(til_module_context_t *context, til_stream_t *stream, unsigned ticks, unsigned cpu, til_fb_fragment_t **fragment_ptr)
{
droste_context_t *ctxt = (droste_context_t *)context;
til_fb_fragment_t *fragment = *fragment_ptr;
til_fb_fragment_t *snapshot = ctxt->snapshot;
if (!snapshot)
return;
for (unsigned y = fragment->y; y < fragment->y + fragment->height; y++) {
for (unsigned x = fragment->x; x < fragment->x + fragment->width; x++) {
uint32_t color;
color = til_fb_fragment_get_pixel_clipped(snapshot, x << 1, y << 1);
til_fb_fragment_put_pixel_unchecked(fragment, 0, x, y, color);
}
}
}
static int droste_finish_frame(til_module_context_t *context, til_stream_t *stream, unsigned int ticks, til_fb_fragment_t **fragment_ptr)
{
droste_context_t *ctxt = (droste_context_t *)context;
/* if we have a stowed frame clean it up */
if (ctxt->snapshot)
ctxt->snapshot = til_fb_fragment_reclaim(ctxt->snapshot);
/* stow the new frame for the next time around to sample from */
ctxt->snapshot = til_fb_fragment_snapshot(fragment_ptr, 1);
return 0;
}
til_module_t droste_module = {
.create_context = droste_create_context,
.destroy_context = droste_destroy_context,
.prepare_frame = droste_prepare_frame,
.render_fragment = droste_render_fragment,
.finish_frame = droste_finish_frame,
.name = "droste",
.description = "Droste effect (threaded)",
.author = "Vito Caputo <vcaputo@pengaru.com>",
.flags = TIL_MODULE_OVERLAYABLE | TIL_MODULE_EXPERIMENTAL,
};
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