const int LogicDataSnapshot::MipMapScalePower = 4;
const int LogicDataSnapshot::MipMapScaleFactor = 1 << MipMapScalePower;
+const float LogicDataSnapshot::LogMipMapScaleFactor = logf(MipMapScaleFactor);
const uint64_t LogicDataSnapshot::MipMapDataUnit = 64*1024; // bytes
LogicDataSnapshot::LogicDataSnapshot(
void LogicDataSnapshot::get_subsampled_edges(
std::vector<EdgePair> &edges,
int64_t start, int64_t end,
- int64_t quantization_length, int sig_index)
+ float min_length, int sig_index)
{
+ int64_t index = start;
+ int level;
+ bool last_sample;
+ bool fast_forward;
+
assert(start >= 0);
- assert(end < get_sample_count());
+ assert(end <= get_sample_count());
assert(start <= end);
- assert(quantization_length > 0);
+ assert(min_length > 0);
assert(sig_index >= 0);
assert(sig_index < SR_MAX_NUM_PROBES);
- const uint64_t sig_mask = 1 << sig_index;
+ const int64_t block_length = (int64_t)max(min_length, 1.0f);
+ const int min_level = max((int)floorf(logf(min_length) /
+ LogMipMapScaleFactor) - 1, 0);
+ const uint64_t sig_mask = 1ULL << sig_index;
- // Add the initial state
- bool last_sample = get_sample(start) & sig_mask;
- edges.push_back(pair<int64_t, bool>(start, last_sample));
+ // Store the initial state
+ last_sample = (get_sample(start) & sig_mask) != 0;
+ edges.push_back(pair<int64_t, bool>(index++, last_sample));
- for(int64_t i = start + 1; i < end; i++)
+ while(index + block_length <= end)
{
- const bool sample = get_sample(i) & sig_mask;
+ //----- Continue to search -----//
+ level = min_level;
+ fast_forward = true;
- // Check if we hit an edge
- if(sample != last_sample)
+ if(min_length < MipMapScaleFactor)
+ {
+ // Search individual samples up to the beginning of
+ // the next first level mip map block
+ const uint64_t final_index = min(end,
+ pow2_ceil(index, MipMapScalePower));
+
+ for(index;
+ index < final_index &&
+ (index & ~(~0 << MipMapScalePower)) != 0;
+ index++)
+ {
+ const bool sample =
+ (get_sample(index) & sig_mask) != 0;
+
+ // If there was a change we cannot fast forward
+ if(sample != last_sample) {
+ fast_forward = false;
+ break;
+ }
+ }
+ }
+ else
{
- // Take the last sample of the quanization block
- const int64_t final_index =
- min((i - (i % quantization_length) +
- quantization_length - 1), end);
-
- // Store the final state
- const bool final_sample = get_sample(final_index) & sig_mask;
- edges.push_back(pair<int64_t, bool>(
- final_index, final_sample));
-
- // Continue to sampling
- i = final_index;
- last_sample = final_sample;
+ // If resolution is less than a mip map block,
+ // round up to the beginning of the mip-map block
+ // for this level of detail
+ const int min_level_scale_power =
+ (level + 1) * MipMapScalePower;
+ index = pow2_ceil(index, min_level_scale_power);
+ if(index >= end)
+ break;
+
+ // We can fast forward only if there was no change
+ const bool sample =
+ (get_sample(index) & sig_mask) != 0;
+ fast_forward = last_sample == sample;
+ }
+
+ if(fast_forward) {
+
+ // Fast forward: This involves zooming out to higher
+ // levels of the mip map searching for changes, then
+ // zooming in on them to find the point where the edge
+ // begins.
+
+ // Slide right and zoom out at the beginnings of mip-map
+ // blocks until we encounter a change
+ while(1) {
+ const int level_scale_power =
+ (level + 1) * MipMapScalePower;
+ const uint64_t offset =
+ index >> level_scale_power;
+ assert(offset >= 0);
+
+ // Check if we reached the last block at this
+ // level, or if there was a change in this block
+ if(offset >= _mip_map[level].length ||
+ (get_subsample(level, offset) &
+ sig_mask))
+ break;
+
+ if((offset & ~(~0 << MipMapScalePower)) == 0) {
+ // If we are now at the beginning of a
+ // higher level mip-map block ascend one
+ // level
+ if(level + 1 >= ScaleStepCount ||
+ !_mip_map[level + 1].data)
+ break;
+
+ level++;
+ } else {
+ // Slide right to the beginning of the
+ // next mip map block
+ index = pow2_ceil(index + 1,
+ level_scale_power);
+ }
+ }
+
+ // Zoom in, and slide right until we encounter a change,
+ // and repeat until we reach min_level
+ while(1) {
+ assert(_mip_map[level].data);
+
+ const int level_scale_power =
+ (level + 1) * MipMapScalePower;
+ const uint64_t offset =
+ index >> level_scale_power;
+ assert(offset >= 0);
+
+ // Check if we reached the last block at this
+ // level, or if there was a change in this block
+ if(offset >= _mip_map[level].length ||
+ (get_subsample(level, offset) &
+ sig_mask)) {
+ // Zoom in unless we reached the minimum
+ // zoom
+ if(level == min_level)
+ break;
+
+ level--;
+ } else {
+ // Slide right to the beginning of the
+ // next mip map block
+ index = pow2_ceil(index + 1,
+ level_scale_power);
+ }
+ }
+
+ // If individual samples within the limit of resolution,
+ // do a linear search for the next transition within the
+ // block
+ if(min_length < MipMapScaleFactor) {
+ for(index; index < end; index++) {
+ const bool sample = (get_sample(index) &
+ sig_mask) != 0;
+ if(sample != last_sample)
+ break;
+ }
+ }
}
+
+ //----- Store the edge -----//
+
+ // Take the last sample of the quanization block
+ const int64_t final_index = index + block_length;
+ if(index + block_length > end)
+ break;
+
+ // Store the final state
+ const bool final_sample =
+ (get_sample(final_index - 1) & sig_mask) != 0;
+ edges.push_back(pair<int64_t, bool>(index, final_sample));
+
+ index = final_index;
+ last_sample = final_sample;
}
// Add the final state
edges.push_back(pair<int64_t, bool>(end,
get_sample(end) & sig_mask));
}
+
+uint64_t LogicDataSnapshot::get_subsample(int level, uint64_t offset) const
+{
+ assert(level >= 0);
+ assert(_mip_map[level].data);
+ return *(uint64_t*)((uint8_t*)_mip_map[level].data +
+ _unit_size * offset);
+}
+
+int64_t LogicDataSnapshot::pow2_ceil(int64_t x, unsigned int power)
+{
+ const int64_t p = 1 << power;
+ return ((x < 0) ? x : (x + p - 1)) / p * p;
+}