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Evas ETC2: Fix alpha encoding with high quality 

Use an exhaustive search when encoding alpha at high quality.
This can be very slow if we don't have a perfect solution.
This commit is contained in:
Jean-Philippe Andre 2014-06-09 19:34:34 +09:00
parent 90f58b2a57
commit 878641f6dc
1 changed files with 22 additions and 15 deletions
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37
src/static_libs/rg_etc/etc2_encoder.c
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@ -198,10 +198,10 @@ static int
_etc2_alpha_encode(uint8_t *etc2_alpha, const uint32_t *bgra,
const rg_etc1_pack_params *params)
{
int alphas[16], avg = 0, diff = 0, maxDiff = INT_MAX, minErr = INT_MAX;
int alphas[16], avg = 0, diff = 0, maxDiff = 0, minErr = INT_MAX;
int base_codeword;
int multiplier, bestMult = 0;
int modifierIdx, bestIdx = 0;
int modifierIdx, bestIdx = 0, bestBase = 128;
int err, base_range, base_step = 1, max_error = 0;
// Try to select the best alpha value (avg)
@ -215,7 +215,7 @@ _etc2_alpha_encode(uint8_t *etc2_alpha, const uint32_t *bgra,
for (int i = 0; i < 16; i++)
{
int thisDiff = ABS(alphas[i] - avg);
maxDiff = MIN(thisDiff, maxDiff);
maxDiff = MAX(thisDiff, maxDiff);
diff += thisDiff;
}
@ -234,27 +234,29 @@ _etc2_alpha_encode(uint8_t *etc2_alpha, const uint32_t *bgra,
{
// The follow parameters are completely arbitrary.
// Need some real testing.
case rg_etc1_high_quality:
base_range = 15;
case rg_etc1_high_quality: // exhaustive search
base_range = 255;
base_step = 1;
break;
case rg_etc1_medium_quality:
base_range = 6;
base_step = 2;
case rg_etc1_medium_quality: // tweaked for "decent" results
base_range = 40;
base_step = 4;
break;
case rg_etc1_low_quality:
base_range = 0;
case rg_etc1_low_quality: // fast (not even fastest)
base_range = 8;
base_step = 4;
break;
}
// for loop avg, avg-1, avg+1, avg-2, avg+2, ...
for (int step = 0; step < base_range; step += base_step)
for (base_codeword = avg - step; base_codeword <= avg + step; base_codeword += 2 * step)
for (base_codeword = CLAMP(avg - step);
base_codeword <= CLAMP(avg + step);)
{
for (modifierIdx = 0; modifierIdx < 16; modifierIdx++)
for (multiplier = 0; multiplier < 16; multiplier++)
{
if ((ABS(multiplier * kAlphaModifiers[modifierIdx][3])) < maxDiff)
if ((ABS(multiplier * kAlphaModifiers[modifierIdx][3]) + ABS(base_codeword - avg)) < maxDiff)
continue;
err = _etc2_alpha_block_pack(etc2_alpha, base_codeword,
@ -264,16 +266,21 @@ _etc2_alpha_encode(uint8_t *etc2_alpha, const uint32_t *bgra,
minErr = err;
bestMult = multiplier;
bestIdx = modifierIdx;
if (err < max_error)
bestBase = base_codeword;
if (err <= max_error)
goto pack_now;
}
}
if (step <= 0) break;
if (base_codeword < 255)
base_codeword = CLAMP(base_codeword + 2 * step);
else
break;
}
pack_now:
err = _etc2_alpha_block_pack(etc2_alpha, base_codeword,
err = _etc2_alpha_block_pack(etc2_alpha, bestBase,
bestMult, bestIdx, bgra, EINA_TRUE);
return err;
}
@ -986,7 +993,7 @@ etc2_rgba8_block_pack(unsigned char *etc2, const unsigned int *bgra,
#ifdef DEBUG
cnt[bestSolution]++;
DBG("Block count by mode: ETC1: %d T/H: %d Planar: %d", cnt[0], cnt[1], cnt[2]);
DBG("Block count by mode: ETC1: %d T/H: %d Planar: %d. Err %d", cnt[0], cnt[1], cnt[2], minErr);
#endif
return minErr;