mirror of https://github.com/OpenTTD/OpenTTD.git
178 lines
6.2 KiB
C++
178 lines
6.2 KiB
C++
/*
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* This file is part of OpenTTD.
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* 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.
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* 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.
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* 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/>.
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*/
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/** @file viewport_sprite_sorter_sse4.cpp Sprite sorter that uses SSE4.1. */
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#ifdef WITH_SSE
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#include "stdafx.h"
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#include "cpu.h"
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#include "smmintrin.h"
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#include "viewport_sprite_sorter.h"
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#include <forward_list>
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#include <stack>
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#include "safeguards.h"
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#ifdef POINTER_IS_64BIT
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static_assert((sizeof(ParentSpriteToDraw) % 16) == 0);
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# define LOAD_128 _mm_load_si128
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#else
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# define LOAD_128 _mm_loadu_si128
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#endif
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GNU_TARGET("sse4.1")
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void ViewportSortParentSpritesSSE41(ParentSpriteToSortVector *psdv)
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{
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if (psdv->size() < 2) return;
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const __m128i mask_ptest = _mm_setr_epi8(-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 0, 0, 0);
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/* We rely on sprites being, for the most part, already ordered.
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* So we don't need to move many of them and can keep track of their
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* order efficiently by using stack. We always move sprites to the front
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* of the current position, i.e. to the top of the stack.
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* Also use special constants to indicate sorting state without
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* adding extra fields to ParentSpriteToDraw structure.
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*/
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const uint32_t ORDER_COMPARED = UINT32_MAX; // Sprite was compared but we still need to compare the ones preceding it
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const uint32_t ORDER_RETURNED = UINT32_MAX - 1; // Mark sorted sprite in case there are other occurrences of it in the stack
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std::stack<ParentSpriteToDraw *> sprite_order;
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uint32_t next_order = 0;
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std::forward_list<std::pair<int64_t, ParentSpriteToDraw *>> sprite_list; // We store sprites in a list sorted by xmin+ymin
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/* Initialize sprite list and order. */
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for (auto p = psdv->rbegin(); p != psdv->rend(); p++) {
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sprite_list.emplace_front((*p)->xmin + (*p)->ymin, *p);
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sprite_order.push(*p);
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(*p)->order = next_order++;
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}
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sprite_list.sort();
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std::vector<ParentSpriteToDraw *> preceding; // Temporarily stores sprites that precede current and their position in the list
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auto preceding_prev = sprite_list.begin(); // Store iterator in case we need to delete a single preciding sprite
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auto out = psdv->begin(); // Iterator to output sorted sprites
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while (!sprite_order.empty()) {
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auto s = sprite_order.top();
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sprite_order.pop();
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/* Sprite is already sorted, ignore it. */
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if (s->order == ORDER_RETURNED) continue;
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/* Sprite was already compared, just need to output it. */
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if (s->order == ORDER_COMPARED) {
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*(out++) = s;
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s->order = ORDER_RETURNED;
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continue;
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}
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preceding.clear();
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/* We only need sprites with xmin <= s->xmax && ymin <= s->ymax && zmin <= s->zmax
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* So by iterating sprites with xmin + ymin <= s->xmax + s->ymax
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* we get all we need and some more that we filter out later.
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* We don't include zmin into the sum as there are usually more neighbors on x and y than z
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* so including it will actually increase the amount of false positives.
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* Also min coordinates can be > max so using max(xmin, xmax) + max(ymin, ymax)
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* to ensure that we iterate the current sprite as we need to remove it from the list.
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*/
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auto ssum = std::max(s->xmax, s->xmin) + std::max(s->ymax, s->ymin);
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auto prev = sprite_list.before_begin();
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auto x = sprite_list.begin();
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while (x != sprite_list.end() && ((*x).first <= ssum)) {
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auto p = (*x).second;
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if (p == s) {
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/* We found the current sprite, remove it and move on. */
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x = sprite_list.erase_after(prev);
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continue;
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}
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auto p_prev = prev;
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prev = x++;
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/* Check that p->xmin <= s->xmax && p->ymin <= s->ymax && p->zmin <= s->zmax */
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__m128i s_max = LOAD_128((__m128i*) &s->xmax);
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__m128i p_min = LOAD_128((__m128i*) &p->xmin);
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__m128i r1 = _mm_cmplt_epi32(s_max, p_min);
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if (!_mm_testz_si128(mask_ptest, r1))
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continue;
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/* Check if sprites overlap, i.e.
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* s->xmin <= p->xmax && s->ymin <= p->ymax && s->zmin <= p->zmax
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*/
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__m128i s_min = LOAD_128((__m128i*) &s->xmin);
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__m128i p_max = LOAD_128((__m128i*) &p->xmax);
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__m128i r2 = _mm_cmplt_epi32(p_max, s_min);
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if (_mm_testz_si128(mask_ptest, r2)) {
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/* Use X+Y+Z as the sorting order, so sprites closer to the bottom of
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* the screen and with higher Z elevation, are drawn in front.
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* Here X,Y,Z are the coordinates of the "center of mass" of the sprite,
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* i.e. X=(left+right)/2, etc.
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* However, since we only care about order, don't actually divide / 2
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*/
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if (s->xmin + s->xmax + s->ymin + s->ymax + s->zmin + s->zmax <=
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p->xmin + p->xmax + p->ymin + p->ymax + p->zmin + p->zmax) {
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continue;
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}
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}
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preceding.push_back(p);
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preceding_prev = p_prev;
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}
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if (preceding.empty()) {
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/* No preceding sprites, add current one to the output */
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*(out++) = s;
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s->order = ORDER_RETURNED;
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continue;
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}
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/* Optimization for the case when we only have 1 sprite to move. */
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if (preceding.size() == 1) {
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auto p = preceding[0];
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/* We can only output the preceding sprite if there can't be any other sprites preceding it. */
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if (p->xmax <= s->xmax && p->ymax <= s->ymax && p->zmax <= s->zmax) {
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p->order = ORDER_RETURNED;
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s->order = ORDER_RETURNED;
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sprite_list.erase_after(preceding_prev);
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*(out++) = p;
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*(out++) = s;
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continue;
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}
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}
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/* Sort all preceding sprites by order and assign new orders in reverse (as original sorter did). */
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std::sort(preceding.begin(), preceding.end(), [](const ParentSpriteToDraw *a, const ParentSpriteToDraw *b) {
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return a->order > b->order;
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});
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s->order = ORDER_COMPARED;
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sprite_order.push(s); // Still need to output so push it back for now
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for (auto p: preceding) {
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p->order = next_order++;
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sprite_order.push(p);
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}
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}
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}
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/**
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* Check whether the current CPU supports SSE 4.1.
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* @return True iff the CPU supports SSE 4.1.
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*/
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bool ViewportSortParentSpritesSSE41Checker()
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{
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return HasCPUIDFlag(1, 2, 19);
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}
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#endif /* WITH_SSE */
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