void sort(Itr begin, Itr end)
{
_shuffle(begin, end);
_sort(begin, end);
_insertion_sort(begin, end);
}
void _sort_rects(DArray rects_in) {
assert(rects_in.size > 1);
// Insertion sort for small buffers
if(rects_in.size <= 8) {
_insertion_sort(rects_in);
return;
}
// Assure out buffer is big enough
rects_out.size = 0;
if(rects_out.reserved < rects_in.size)
darray_reserve(&rects_out, MAX(rects_in.size, rects_out.reserved*2));
assert(rects_out.reserved >= rects_in.size);
assert(rects_out.item_size == rects_in.item_size);
TexturedRectDesc* r_in = DARRAY_DATA_PTR(rects_in, TexturedRectDesc);
TexturedRectDesc* r_out = DARRAY_DATA_PTR(rects_out, TexturedRectDesc);
uint i, unique_textures = 0, switches = 0;
memset(radix_counts, 0, sizeof(radix_counts));
// If there is more than 255 textures our simple count sort won't work
assert(textures.size < 256);
// Calculate histogram, unsorted texture switches, unique textures
for(i = 0; i < rects_in.size; ++i) {
size_t idx = r_in[i].tex & 0xFF;
radix_counts[idx]++;
if (radix_counts[idx] == 1)
unique_textures++;
if(i > 0 && r_in[i].tex != r_in[i-1].tex)
switches++;
}
// Don't bother sorting if it wouldn't decrease batch count
if(unique_textures < 3 || unique_textures == switches)
return;
// Convert histogram to start indices
for(i = 1; i < 256; ++i)
radix_counts[i] = radix_counts[i-1] + radix_counts[i];
// Count sort (single pass of radix sort - texture amount is not a large
// number)
uint r0 = 0;
for(i = 0; i < rects_in.size; ++i) {
size_t idx = r_in[i].tex & 0xFF;
uint* dest = idx ? &radix_counts[idx-1] : &r0;
r_out[(*dest)++] = r_in[i];
}
memcpy(r_in, r_out, rects_in.size * rects_in.item_size);
}
