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sexblitter: collect minimum difference as we go

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nick black 2020-10-28 04:18:20 -04:00 committed by Nick Black
parent e1582a2784
commit 21c579633f
1 changed files with 33 additions and 10 deletions
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43
src/lib/blit.c
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@ -495,6 +495,14 @@ collect_diffs(unsigned* diff, unsigned bitstring, const uint8_t* rgba1,
return false;
}
// if the candidate diff is less than the minimum diff, update mindiffidx
static inline void
collect_mindiff(unsigned* mindiffidx, const unsigned diffs[15], unsigned candidate){
if(diffs[candidate] < diffs[*mindiffidx]){
*mindiffidx = candidate;
}
}
// sextant check for transparency. returns an EGC if we found transparent pixels
// and have solved for colors (this EGC ought then be loaded into the cell).
// returns NULL otherwise. transparency trumps everything else in terms of
@ -509,38 +517,53 @@ strans_check(uint64_t* channels, bool bgr, bool blendcolors, unsigned diffs[15],
const uint8_t* rgbbase_l2, const uint8_t* rgbbase_r2,
const uint8_t* rgbbase_l3, const uint8_t* rgbbase_r3){
// there are 15 sums of absolute differences between pixels:
// l1 - r1, l1 - l2, l1 - r2, l1 - l3, l1 - r3
// r1 - l2, r1 - r2, r1 - l3, r1 - r3
// l2 - r2, l2 - l3, l2 - r3
// r2 - l3, r2 - r3
// l3 - r3
// l1 - r1, l1 - l2, l1 - r2, l1 - l3, l1 - r3 (0, 1, 2, 3, 4)
// r1 - l2, r1 - r2, r1 - l3, r1 - r3 (5, 6, 7, 8)
// l2 - r2, l2 - l3, l2 - r3 (9, 10, 11)
// r2 - l3, r2 - r3 (12, 13)
// l3 - r3 (14)
// if either pixel is transparent, the difference is UINT_MAX
unsigned bitstring = 0;
unsigned div = 0;
unsigned r, g, b;
r = g = b = 0;
bool allzerodiffs = true;
unsigned mindiffidx = 0;
strans_fold(&bitstring, 1u, rgbbase_l1, bgr, &r, &g, &b, &div);
strans_fold(&bitstring, 2u, rgbbase_r1, bgr, &r, &g, &b, &div);
allzerodiffs &= collect_diffs(&diffs[0], bitstring, rgbbase_r1, 2u, rgbbase_l1, 1u);
strans_fold(&bitstring, 4u, rgbbase_l2, bgr, &r, &g, &b, &div);
allzerodiffs &= collect_diffs(&diffs[1], bitstring, rgbbase_l2, 4u, rgbbase_l1, 1u);
collect_mindiff(&mindiffidx, diffs, 1);
allzerodiffs &= collect_diffs(&diffs[5], bitstring, rgbbase_l2, 4u, rgbbase_r1, 2u);
collect_mindiff(&mindiffidx, diffs, 5);
strans_fold(&bitstring, 8u, rgbbase_r2, bgr, &r, &g, &b, &div);
allzerodiffs &= collect_diffs(&diffs[2], bitstring, rgbbase_r2, 8u, rgbbase_l1, 1u);
allzerodiffs &= collect_diffs(&diffs[6], bitstring, rgbbase_r2, 8u, rgbbase_r1, 2u);
allzerodiffs &= collect_diffs(&diffs[9], bitstring, rgbbase_r2, 8u, rgbbase_l1, 4u);
allzerodiffs &= collect_diffs(&diffs[9], bitstring, rgbbase_r2, 8u, rgbbase_l2, 4u);
collect_mindiff(&mindiffidx, diffs, 2);
collect_mindiff(&mindiffidx, diffs, 6);
collect_mindiff(&mindiffidx, diffs, 9);
strans_fold(&bitstring, 16u, rgbbase_l3, bgr, &r, &g, &b, &div);
allzerodiffs &= collect_diffs(&diffs[3], bitstring, rgbbase_l3, 16u, rgbbase_l1, 1u);
allzerodiffs &= collect_diffs(&diffs[7], bitstring, rgbbase_l3, 16u, rgbbase_r1, 2u);
allzerodiffs &= collect_diffs(&diffs[9], bitstring, rgbbase_l3, 16u, rgbbase_l2, 4u);
allzerodiffs &= collect_diffs(&diffs[10], bitstring, rgbbase_l3, 16u, rgbbase_l2, 4u);
allzerodiffs &= collect_diffs(&diffs[12], bitstring, rgbbase_l3, 16u, rgbbase_r2, 8u);
collect_mindiff(&mindiffidx, diffs, 3);
collect_mindiff(&mindiffidx, diffs, 7);
collect_mindiff(&mindiffidx, diffs, 10);
collect_mindiff(&mindiffidx, diffs, 12);
strans_fold(&bitstring, 32u, rgbbase_r3, bgr, &r, &g, &b, &div);
allzerodiffs &= collect_diffs(&diffs[4], bitstring, rgbbase_r3, 32u, rgbbase_l1, 1u);
allzerodiffs &= collect_diffs(&diffs[8], bitstring, rgbbase_r3, 32u, rgbbase_r1, 2u);
allzerodiffs &= collect_diffs(&diffs[10], bitstring, rgbbase_r3, 32u, rgbbase_l2, 4u);
allzerodiffs &= collect_diffs(&diffs[11], bitstring, rgbbase_r3, 32u, rgbbase_r2, 8u);
allzerodiffs &= collect_diffs(&diffs[13], bitstring, rgbbase_r3, 32u, rgbbase_l3, 16u);
allzerodiffs &= collect_diffs(&diffs[11], bitstring, rgbbase_r3, 32u, rgbbase_l2, 4u);
allzerodiffs &= collect_diffs(&diffs[13], bitstring, rgbbase_r3, 32u, rgbbase_r2, 8u);
allzerodiffs &= collect_diffs(&diffs[14], bitstring, rgbbase_r3, 32u, rgbbase_l3, 16u);
collect_mindiff(&mindiffidx, diffs, 4);
collect_mindiff(&mindiffidx, diffs, 8);
collect_mindiff(&mindiffidx, diffs, 11);
collect_mindiff(&mindiffidx, diffs, 13);
collect_mindiff(&mindiffidx, diffs, 14);
if(!bitstring){ // no transparent pixels, use main solver unless all are same
if(allzerodiffs){
channels_set_bg_rgb8(channels, r / div, g / div, b / div);