Alembic: speed up export of packed UV islands.

Differential Revision: https://developer.blender.org/D3510

1 files changed, 31 insertions, 6 deletions

diff --git a/source/blender/alembic/intern/abc_customdata.cc b/source/blender/alembic/intern/abc_customdata.cc
index b98d82f0c7d..8ab9f1118f4 100644
--- a/source/blender/alembic/intern/abc_customdata.cc
+++ b/source/blender/alembic/intern/abc_customdata.cc
@@ -26,6 +26,7 @@
 
 #include <Alembic/AbcGeom/All.h>
 #include <algorithm>
+#include <unordered_map>
 
 extern "C" {
 #include "DNA_customdata_types.h"
@@ -51,6 +52,27 @@ using Alembic::Abc::V2fArraySample;
 using Alembic::AbcGeom::OV2fGeomParam;
 using Alembic::AbcGeom::OC4fGeomParam;
 
+
+static inline uint64_t uv_to_hash_key(Imath::V2f v)
+{
+	/* Convert -0.0f to 0.0f, so bitwise comparison works. */
+	if (v.x == 0.0f) {
+		v.x = 0.0f;
+	}
+	if (v.y == 0.0f) {
+		v.y = 0.0f;
+	}
+
+	/* Pack floats in 64bit. */
+	union {
+		float xy[2];
+		uint64_t key;
+	} tmp;
+	tmp.xy[0] = v.x;
+	tmp.xy[1] = v.y;
+	return tmp.key;
+}
+
 static void get_uvs(const CDStreamConfig &config,
                     std::vector<Imath::V2f> &uvs,
                     std::vector<uint32_t> &uvidx,
@@ -84,6 +106,9 @@ static void get_uvs(const CDStreamConfig &config,
 		}
 	}
 	else {
+		std::unordered_map<uint64_t, int> idx_map;
+		int idx_count = 0;
+
 		for (int i = 0; i < num_poly; ++i) {
 			MPoly &current_poly = polygons[i];
 			MLoopUV *loopuvpoly = mloopuv_array + current_poly.loopstart + current_poly.totloop;
@@ -91,15 +116,15 @@ static void get_uvs(const CDStreamConfig &config,
 			for (int j = 0; j < current_poly.totloop; ++j) {
 				loopuvpoly--;
 				Imath::V2f uv(loopuvpoly->uv[0], loopuvpoly->uv[1]);
-
-				std::vector<Imath::V2f>::iterator it = std::find(uvs.begin(), uvs.end(), uv);
-
-				if (it == uvs.end()) {
-					uvidx.push_back(uvs.size());
+				uint64_t k = uv_to_hash_key(uv);
+				std::unordered_map<uint64_t, int>::iterator it = idx_map.find(k);
+				if (it == idx_map.end()) {
+					idx_map[k] = idx_count;
 					uvs.push_back(uv);
+					uvidx.push_back(idx_count++);
 				}
 				else {
-					uvidx.push_back(std::distance(uvs.begin(), it));
+					uvidx.push_back(it->second);
 				}
 			}
 		}