[Bf-blender-cvs] [c486da0238b] master: Mikktspace: Reduce number of data queries to caller
Lukas Stockner
noreply at git.blender.org
Sat Apr 23 15:19:53 CEST 2022
Commit: c486da0238bd61eb304f402bd07a9ae43c3733e5
Author: Lukas Stockner
Date: Sun Apr 17 20:27:57 2022 +0200
Branches: master
https://developer.blender.org/rBc486da0238bd61eb304f402bd07a9ae43c3733e5
Mikktspace: Reduce number of data queries to caller
The current code for computing tangents is not exactly fast.
This has been a long-standing issue, and recently came up again with T97378.
The main bottleneck is fetching the mesh data, since it's handled through a callback system and each vertex might have its data queried dozens of times.
I've tried a lot of things to optimize `mikktspace.c`, but unfortunately most weren't that useful:
- Vectorizing SVec3 gives a ~5% speedup, but I'm not sure if the additional ~70 lines of code are worth it
- Keeping an internal copy of the data instead of re-querying all the time helps a lot (~50-60% time reduction), but requires a lot of extra memory (~100 byte per face)
- Going C++ and replacing the internal quicksort with std::sort shows no difference
- Restructuring the entire file to be a header-only library so that the callbacks can be inlined gives ~10% reduction, but is a major change and deviation from the original library
In the end, two simple fixes that actually help remain:
- Don't re-query the number of faces in each loop iteration
- Don't bother looking for identical vertices if there's only one vertex with that hash
With this, time for the test case in T97378 goes from 6.64sec to 4.92sec. It's something I guess.
I feel like completely refactoring this library would not be a bad idea at some point, but for now it does the job...
Differential Revision: https://developer.blender.org/D14675
===================================================================
M intern/mikktspace/mikktspace.c
===================================================================
diff --git a/intern/mikktspace/mikktspace.c b/intern/mikktspace/mikktspace.c
index 794590d30a4..e39ac4bb6ef 100644
--- a/intern/mikktspace/mikktspace.c
+++ b/intern/mikktspace/mikktspace.c
@@ -565,23 +565,26 @@ static void GenerateSharedVerticesIndexList(int piTriList_in_and_out[],
break;
}
- for (int i = blockstart; i < blockend; i++) {
- int index1 = piTriList_in_and_out[indices[i]];
- const SVec3 vP = GetPosition(pContext, index1);
- const SVec3 vN = GetNormal(pContext, index1);
- const SVec3 vT = GetTexCoord(pContext, index1);
- for (int i2 = i + 1; i2 < blockend; i2++) {
- int index2 = piTriList_in_and_out[indices[i2]];
- if (index1 == index2)
- continue;
-
- if (veq(vP, GetPosition(pContext, index2)) && veq(vN, GetNormal(pContext, index2)) &&
- veq(vT, GetTexCoord(pContext, index2))) {
- piTriList_in_and_out[indices[i2]] = index1;
- /* Once i2>i has been identified as a duplicate, we can stop since any
- * i3>i2>i that is a duplicate of i (and therefore also i2) will also be
- * compared to i2 and therefore be identified there anyways. */
- break;
+ /* If there's only one vertex with this hash, we don't have anything to compare. */
+ if (blockend > blockstart + 1) {
+ for (int i = blockstart; i < blockend; i++) {
+ int index1 = piTriList_in_and_out[indices[i]];
+ const SVec3 vP = GetPosition(pContext, index1);
+ const SVec3 vN = GetNormal(pContext, index1);
+ const SVec3 vT = GetTexCoord(pContext, index1);
+ for (int i2 = i + 1; i2 < blockend; i2++) {
+ int index2 = piTriList_in_and_out[indices[i2]];
+ if (index1 == index2)
+ continue;
+
+ if (veq(vP, GetPosition(pContext, index2)) && veq(vN, GetNormal(pContext, index2)) &&
+ veq(vT, GetTexCoord(pContext, index2))) {
+ piTriList_in_and_out[indices[i2]] = index1;
+ /* Once i2>i has been identified as a duplicate, we can stop since any
+ * i3>i2>i that is a duplicate of i (and therefore also i2) will also be
+ * compared to i2 and therefore be identified there anyways. */
+ break;
+ }
}
}
}
@@ -645,7 +648,8 @@ static int GenerateInitialVerticesIndexList(STriInfo pTriInfos[],
{
int iTSpacesOffs = 0, f = 0, t = 0;
int iDstTriIndex = 0;
- for (f = 0; f < pContext->m_pInterface->m_getNumFaces(pContext); f++) {
+ const int iNrFaces = pContext->m_pInterface->m_getNumFaces(pContext);
+ for (f = 0; f < iNrFaces; f++) {
const int verts = pContext->m_pInterface->m_getNumVerticesOfFace(pContext, f);
if (verts != 3 && verts != 4)
continue;
More information about the Bf-blender-cvs
mailing list