Function updateEdgeAdjacency

SHTest/Externals/meshoptimizer/simplifier.cpp:51–108

}

static void updateEdgeAdjacency(EdgeAdjacency& adjacency, const unsigned int* indices, size_t index_count, size_t vertex_count, const unsigned int* remap)
{
	size_t face_count = index_count / 3;
	unsigned int* offsets = adjacency.offsets + 1;
	EdgeAdjacency::Edge* data = adjacency.data;

	// fill edge counts
	memset(offsets, 0, vertex_count * sizeof(unsigned int));

	for (size_t i = 0; i < index_count; ++i)
	{
		unsigned int v = remap ? remap[indices[i]] : indices[i];
		assert(v < vertex_count);

		offsets[v]++;
	}

	// fill offset table
	unsigned int offset = 0;

	for (size_t i = 0; i < vertex_count; ++i)
	{
		unsigned int count = offsets[i];
		offsets[i] = offset;
		offset += count;
	}

	assert(offset == index_count);

	// fill edge data
	for (size_t i = 0; i < face_count; ++i)
	{
		unsigned int a = indices[i * 3 + 0], b = indices[i * 3 + 1], c = indices[i * 3 + 2];

		if (remap)
		{
			a = remap[a];
			b = remap[b];
			c = remap[c];
		}

		data[offsets[a]].next = b;
		data[offsets[a]].prev = c;
		offsets[a]++;

		data[offsets[b]].next = c;
		data[offsets[b]].prev = a;
		offsets[b]++;

		data[offsets[c]].next = a;
		data[offsets[c]].prev = b;
		offsets[c]++;
	}

	// finalize offsets
	adjacency.offsets[0] = 0;
	assert(adjacency.offsets[vertex_count] == index_count);
}