[Bf-blender-cvs] [99683f2] master: And one more fix to particle distribution!

Bastien Montagne noreply at git.blender.org
Mon Jul 4 16:15:22 CEST 2016


Commit: 99683f25e8e8bd9b1e9d8f4a0966cc6268c98fb0
Author: Bastien Montagne
Date:   Mon Jul 4 16:10:40 2016 +0200
Branches: master
https://developer.blender.org/rB99683f25e8e8bd9b1e9d8f4a0966cc6268c98fb0

And one more fix to particle distribution!

As pointed by Brecht, previous fix in rB61b49de44940 was actually incomplete,
we could still hit float rounding issue and hence same value in more than one consecutive
items of element_sum.

New solution is a bit different, we remove the 'minimal weight' check, and rather simply
ignores an item when the sum of its normalized weight to previous item's sum does not add
anything. Shall be safe and 100% effective this time!

===================================================================

M	source/blender/blenkernel/intern/particle_distribute.c

===================================================================

diff --git a/source/blender/blenkernel/intern/particle_distribute.c b/source/blender/blenkernel/intern/particle_distribute.c
index c814713..44cf5b1 100644
--- a/source/blender/blenkernel/intern/particle_distribute.c
+++ b/source/blender/blenkernel/intern/particle_distribute.c
@@ -1007,13 +1007,11 @@ static int psys_thread_context_init_distribute(ParticleThreadContext *ctx, Parti
 		MEM_freeN(vweight);
 	}
 
-#define MIN_WEIGHT 1e-7f  /* Weights too small cause issues e.g. with binary search... */
-
 	/* Calculate total weight of all elements */
 	int totmapped = 0;
 	totweight = 0.0f;
 	for (i = 0; i < totelem; i++) {
-		if (element_weight[i] > MIN_WEIGHT) {
+		if (element_weight[i] > 0.0f) {
 			totmapped++;
 			totweight += element_weight[i];
 		}
@@ -1036,22 +1034,21 @@ static int psys_thread_context_init_distribute(ParticleThreadContext *ctx, Parti
 	int *element_map = MEM_mallocN(sizeof(*element_map) * totmapped, __func__);
 	int i_mapped = 0;
 
-	for (i = 0; i < totelem && element_weight[i] <= MIN_WEIGHT; i++);
+	for (i = 0; i < totelem && element_weight[i] == 0.0f; i++);
 	element_sum[i_mapped] = element_weight[i] * inv_totweight;
 	element_map[i_mapped] = i;
 	i_mapped++;
 	for (i++; i < totelem; i++) {
-		if (element_weight[i] > MIN_WEIGHT) {
+		if (element_weight[i] > 0.0f) {
 			element_sum[i_mapped] = element_sum[i_mapped - 1] + element_weight[i] * inv_totweight;
-			BLI_assert(element_sum[i_mapped] > element_sum[i_mapped - 1]);
-			element_map[i_mapped] = i;
-			i_mapped++;
+			/* Skip elements which weight is so small that it does not affect the sum. */
+			if (element_sum[i_mapped] > element_sum[i_mapped - 1]) {
+				element_map[i_mapped] = i;
+				i_mapped++;
+			}
 		}
 	}
-
-	BLI_assert(i_mapped == totmapped);
-
-#undef MIN_WEIGHT
+	totmapped = i_mapped;
 
 	/* Finally assign elements to particles */
 	if ((part->flag & PART_TRAND) || (part->simplify_flag & PART_SIMPLIFY_ENABLE)) {




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