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a/math: Clarify comments in relation history

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This commit is contained in:
Rylie Pavlik 2024-02-07 13:00:09 -06:00
parent 328b9c7c5d
commit 46c443baa0
1 changed files with 6 additions and 3 deletions
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9
src/xrt/auxiliary/math/m_relation_history.cpp
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@ -93,7 +93,7 @@ m_relation_history_get(struct m_relation_history *rh, uint64_t at_timestamp_ns,
const auto b = rh->impl.begin();
const auto e = rh->impl.end();
// find the first element *not less than* our value. the lambda we pass is the comparison
// Find the first element *not less than* our value. the lambda we pass is the comparison
// function, to compare against timestamps.
const auto it =
std::lower_bound(b, e, at_timestamp_ns, [](const relation_history_entry &rhe, uint64_t timestamp) {
@ -104,6 +104,7 @@ m_relation_history_get(struct m_relation_history *rh, uint64_t at_timestamp_ns,
// lower bound is at the end:
// The desired timestamp is after what our buffer contains.
// (pose-prediction)
// Output flags match the most recent buffer entry.
int64_t diff_prediction_ns = static_cast<int64_t>(at_timestamp_ns) - rh->impl.back().timestamp;
double delta_s = time_ns_to_s(diff_prediction_ns);
@ -113,7 +114,8 @@ m_relation_history_get(struct m_relation_history *rh, uint64_t at_timestamp_ns,
return M_RELATION_HISTORY_RESULT_PREDICTED;
}
if (at_timestamp_ns == it->timestamp) {
// exact match
// exact match:
// Flags copied directly along with everything else.
U_LOG_T("Exact match in the buffer!");
*out_relation = it->relation;
return M_RELATION_HISTORY_RESULT_EXACT;
@ -122,6 +124,7 @@ m_relation_history_get(struct m_relation_history *rh, uint64_t at_timestamp_ns,
// lower bound is at the beginning (and it's not an exact match):
// The desired timestamp is before what our buffer contains.
// (an edge case where somebody asks for a really old pose and we do our best)
// Output flags are the same as the input flags for the history entry we use
int64_t diff_prediction_ns = static_cast<int64_t>(at_timestamp_ns) - rh->impl.front().timestamp;
double delta_s = time_ns_to_s(diff_prediction_ns);
U_LOG_T("Extrapolating %f s before the front of the buffer!", delta_s);
@ -141,7 +144,7 @@ m_relation_history_get(struct m_relation_history *rh, uint64_t at_timestamp_ns,
float amount_to_lerp = (float)diff_before / (float)(diff_before + diff_after);
// Copy relation flags
// Copy intersection of relation flags
xrt_space_relation result{};
result.relation_flags = (enum xrt_space_relation_flags)(predecessor.relation.relation_flags &
successor.relation.relation_flags);