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/*
* This file is part of OpenTTD.
* OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
* OpenTTD 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 OpenTTD. If not, see <http://www.gnu.org/licenses/>.
*/
/** @file viewport_sprite_sorter_sse4.cpp Sprite sorter that uses SSE4.1. */
#ifdef WITH_SSE
#include "stdafx.h"
#include "cpu.h"
#include "smmintrin.h"
#include "viewport_sprite_sorter.h"
#include <forward_list>
#include <map>
#include <stack>
#include "safeguards.h"
#ifdef POINTER_IS_64BIT
static_assert((sizeof(ParentSpriteToDraw) % 16) == 0);
# define LOAD_128 _mm_load_si128
#else
# define LOAD_128 _mm_loadu_si128
#endif
void ViewportSortParentSpritesSSE41(ParentSpriteToSortVector *psdv)
{
if (psdv->size() < 2) return;
const __m128i mask_ptest = _mm_setr_epi8(-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 0, 0, 0);
/* We rely on sprites being, for the most part, already ordered.
* So we don't need to move many of them and can keep track of their
* order efficiently by using stack. We always move sprites to the front
* of the current position, i.e. to the top of the stack.
* Also use special constants to indicate sorting state without
* adding extra fields to ParentSpriteToDraw structure.
*/
const uint32 ORDER_COMPARED = UINT32_MAX; // Sprite was compared but we still need to compare the ones preceding it
const uint32 ORDER_RETURNED = UINT32_MAX - 1; // Mark sorted sprite in case there are other occurrences of it in the stack
std::stack<ParentSpriteToDraw *> sprite_order;
uint32 next_order = 0;
std::forward_list<std::pair<int64, ParentSpriteToDraw *>> sprite_list; // We store sprites in a list sorted by xmin+ymin
/* Initialize sprite list and order. */
for (auto p = psdv->rbegin(); p != psdv->rend(); p++) {
sprite_list.push_front(std::make_pair((*p)->xmin + (*p)->ymin, *p));
sprite_order.push(*p);
(*p)->order = next_order++;
}
sprite_list.sort();
std::vector<ParentSpriteToDraw *> preceding; // Temporarily stores sprites that precede current and their position in the list
auto preceding_prev = sprite_list.begin(); // Store iterator in case we need to delete a single preciding sprite
auto out = psdv->begin(); // Iterator to output sorted sprites
while (!sprite_order.empty()) {
auto s = sprite_order.top();
sprite_order.pop();
/* Sprite is already sorted, ignore it. */
if (s->order == ORDER_RETURNED) continue;
/* Sprite was already compared, just need to output it. */
if (s->order == ORDER_COMPARED) {
*(out++) = s;
s->order = ORDER_RETURNED;
continue;
}
preceding.clear();
/* We only need sprites with xmin <= s->xmax && ymin <= s->ymax && zmin <= s->zmax
* So by iterating sprites with xmin + ymin <= s->xmax + s->ymax
* we get all we need and some more that we filter out later.
* We don't include zmin into the sum as there are usually more neighbors on x and y than z
* so including it will actually increase the amount of false positives.
* Also min coordinates can be > max so using max(xmin, xmax) + max(ymin, ymax)
* to ensure that we iterate the current sprite as we need to remove it from the list.
*/
auto ssum = std::max(s->xmax, s->xmin) + std::max(s->ymax, s->ymin);
auto prev = sprite_list.before_begin();
auto x = sprite_list.begin();
while (x != sprite_list.end() && ((*x).first <= ssum)) {
auto p = (*x).second;
if (p == s) {
/* We found the current sprite, remove it and move on. */
x = sprite_list.erase_after(prev);
continue;
}
auto p_prev = prev;
prev = x++;
/* Check that p->xmin <= s->xmax && p->ymin <= s->ymax && p->zmin <= s->zmax */
__m128i s_max = LOAD_128((__m128i*) &s->xmax);
__m128i p_min = LOAD_128((__m128i*) &p->xmin);
__m128i r1 = _mm_cmplt_epi32(s_max, p_min);
if (!_mm_testz_si128(mask_ptest, r1))
continue;
/* Check if sprites overlap, i.e.
* s->xmin <= p->xmax && s->ymin <= p->ymax && s->zmin <= p->zmax
*/
__m128i s_min = LOAD_128((__m128i*) &s->xmin);
__m128i p_max = LOAD_128((__m128i*) &p->xmax);
__m128i r2 = _mm_cmplt_epi32(p_max, s_min);
if (_mm_testz_si128(mask_ptest, r2)) {
/* Use X+Y+Z as the sorting order, so sprites closer to the bottom of
* the screen and with higher Z elevation, are drawn in front.
* Here X,Y,Z are the coordinates of the "center of mass" of the sprite,
* i.e. X=(left+right)/2, etc.
* However, since we only care about order, don't actually divide / 2
*/
if (s->xmin + s->xmax + s->ymin + s->ymax + s->zmin + s->zmax <=
p->xmin + p->xmax + p->ymin + p->ymax + p->zmin + p->zmax) {
continue;
}
}
preceding.push_back(p);
preceding_prev = p_prev;
}
if (preceding.empty()) {
/* No preceding sprites, add current one to the output */
*(out++) = s;
s->order = ORDER_RETURNED;
continue;
}
/* Optimization for the case when we only have 1 sprite to move. */
if (preceding.size() == 1) {
auto p = preceding[0];
/* We can only output the preceding sprite if there can't be any other sprites preceding it. */
if (p->xmax <= s->xmax && p->ymax <= s->ymax && p->zmax <= s->zmax) {
p->order = ORDER_RETURNED;
s->order = ORDER_RETURNED;
sprite_list.erase_after(preceding_prev);
*(out++) = p;
*(out++) = s;
continue;
}
}
/* Sort all preceding sprites by order and assign new orders in reverse (as original sorter did). */
std::sort(preceding.begin(), preceding.end(), [](const ParentSpriteToDraw *a, const ParentSpriteToDraw *b) {
return a->order > b->order;
});
s->order = ORDER_COMPARED;
sprite_order.push(s); // Still need to output so push it back for now
for (auto p: preceding) {
p->order = next_order++;
sprite_order.push(p);
}
}
}
/**
* Check whether the current CPU supports SSE 4.1.
* @return True iff the CPU supports SSE 4.1.
*/
bool ViewportSortParentSpritesSSE41Checker()
{
return HasCPUIDFlag(1, 2, 19);
}
#endif /* WITH_SSE */
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