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Sort objects without extra copying

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This commit is contained in:
Kp 2014-11-21 03:29:28 +00:00
parent 98dcc26080
commit fb521e9b75
1 changed files with 30 additions and 70 deletions
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100
similar/main/render.cpp
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@ -1076,22 +1076,31 @@ static void add_obj_to_seglist(render_state_t &rstate, objnum_t objnum, segnum_t
o.emplace_back(render_state_t::per_segment_state_t::distant_object{objnum});
}
#if defined(DXX_BUILD_DESCENT_I)
#define SORT_LIST_SIZE 50
#elif defined(DXX_BUILD_DESCENT_II)
#define SORT_LIST_SIZE 100
#endif
struct sort_item
struct render_compare_context_t
{
objnum_t objnum;
fix64 dist_squared;
struct element
{
fix64 dist_squared;
};
typedef array<element, MAX_OBJECTS> array_t;
array_t a;
array_t::reference operator[](std::size_t i) { return a[i]; }
array_t::const_reference operator[](std::size_t i) const { return a[i]; }
render_compare_context_t(const render_state_t::per_segment_state_t &segstate)
{
range_for (auto t, segstate.objects)
{
auto objp = &Objects[t.objnum];
auto &e = (*this)[t.objnum];
e.dist_squared = vm_vec_dist2(objp->pos, Viewer_eye);
}
}
};
//compare function for object sort.
static bool compare_func(const sort_item &a,const sort_item &b)
static bool compare_func(const render_compare_context_t &c, const render_state_t::per_segment_state_t::distant_object &a,const render_state_t::per_segment_state_t::distant_object &b)
{
fix64 delta_dist_squared = a.dist_squared - b.dist_squared;
fix64 delta_dist_squared = c[a.objnum].dist_squared - c[b.objnum].dist_squared;
#if defined(DXX_BUILD_DESCENT_II)
const auto obj_a = &Objects[a.objnum];
@ -1124,6 +1133,15 @@ static bool compare_func(const sort_item &a,const sort_item &b)
return delta_dist_squared < 0; //return distance
}
static void sort_segment_object_list(render_state_t::per_segment_state_t &segstate)
{
render_compare_context_t context(segstate);
typedef render_state_t::per_segment_state_t::distant_object distant_object;
const auto predicate = [&context](const distant_object &a, const distant_object &b) { return compare_func(context, a, b); };
auto &v = segstate.objects;
std::sort(v.begin(), v.end(), predicate);
}
static void build_object_lists(render_state_t &rstate)
{
int nn;
@ -1197,65 +1215,7 @@ static void build_object_lists(render_state_t &rstate)
for (nn=0;nn < rstate.N_render_segs;nn++) {
auto segnum = rstate.Render_list[nn];
if (segnum != segment_none) {
array<sort_item, SORT_LIST_SIZE> sort_list;
uint_fast32_t n_sort_items;
auto &v = rstate.render_seg_map[segnum].objects;
int n;
//first count the number of objects & copy into sort list
n_sort_items = 0;
range_for (auto t, v)
if (n_sort_items < SORT_LIST_SIZE-1) { //add if room
sort_list[n_sort_items].objnum = t.objnum;
//NOTE: maybe use depth, not dist - quicker computation
sort_list[n_sort_items].dist_squared = vm_vec_dist2(Objects[t.objnum].pos,Viewer_eye);
n_sort_items++;
}
#if defined(DXX_BUILD_DESCENT_II)
else { //no room for object
int ii;
Int3(); //Get Matt!!!
//Now try to find a place for this object by getting rid
//of an object we don't care about
for (ii=0;ii<SORT_LIST_SIZE;ii++) {
int objnum = sort_list[ii].objnum;
object *obj = &Objects[objnum];
int type = obj->type;
//replace debris & fireballs
if (type == OBJ_DEBRIS || type == OBJ_FIREBALL) {
fix64 dist_squared = vm_vec_dist2(Objects[t.objnum].pos,Viewer_eye);
//don't replace same kind of object unless new
//one is closer
if (Objects[t.objnum].type != type || dist_squared < sort_list[ii].dist_squared) {
sort_list[ii].objnum = t.objnum;
sort_list[ii].dist_squared = dist_squared;
break;
}
}
}
Int3(); //still couldn't find a slot
}
#endif
//now call qsort
std::sort(sort_list.begin(), std::next(sort_list.begin(), n_sort_items), compare_func);
//now copy back into list
n = n_sort_items;
range_for (auto &t, v)
if (n <= 0)
break;
else
t.objnum = sort_list[--n].objnum;
sort_segment_object_list(rstate.render_seg_map[segnum]);
}
}
}