Bugfix [#33852] Scale of a strip in NLA is changed after moving it long distance

using numeric input

When using numeric input to move strips, the strip extent clamping code could
end up prematurely truncating one endpoint. This was because the clamping code
uses the values of the other end (e.g. end for start, and start for end) as one
of the limits on its allowable range to prevent inverted strips.

Now we just set these values twice - the first time, one of the endpoints may
still get truncated (while the other one will be able to go to its correct
value), then the second time both will get set correctly (and validated too).

2 files changed, 10 insertions, 3 deletions

diff --git a/source/blender/editors/transform/transform_generics.c b/source/blender/editors/transform/transform_generics.c
index 2591c61c5ab..d56bb5cb7ef 100644
--- a/source/blender/editors/transform/transform_generics.c
+++ b/source/blender/editors/transform/transform_generics.c
@@ -550,13 +550,20 @@ static void recalcData_nla(TransInfo *t)
 				break;
 		}
 		
-		/* use RNA to write the values... */
-		// TODO: do we need to write in 2 passes to make sure that no truncation goes on?
+		/* Use RNA to write the values to ensure that constraints on these are obeyed
+		 * (e.g. for transition strips, the values are taken from the neighbours)
+		 * 
+		 * NOTE: we write these twice to avoid truncation errors which can arise when
+		 * moving the strips a large distance using numeric input [#33852] 
+		 */
 		RNA_pointer_create(NULL, &RNA_NlaStrip, strip, &strip_ptr);
 		
 		RNA_float_set(&strip_ptr, "frame_start", tdn->h1[0]);
 		RNA_float_set(&strip_ptr, "frame_end", tdn->h2[0]);
 		
+		RNA_float_set(&strip_ptr, "frame_start", tdn->h1[0]);
+		RNA_float_set(&strip_ptr, "frame_end", tdn->h2[0]);
+		
 		/* flush transforms to child strips (since this should be a meta) */
 		BKE_nlameta_flush_transforms(strip);
 		
diff --git a/source/blender/makesrna/intern/rna_nla.c b/source/blender/makesrna/intern/rna_nla.c
index 574f06e9107..2b7f6a182a0 100644
--- a/source/blender/makesrna/intern/rna_nla.c
+++ b/source/blender/makesrna/intern/rna_nla.c
@@ -115,7 +115,7 @@ static void rna_NlaStrip_start_frame_set(PointerRNA *ptr, float value)
 		if (data->prev->type == NLASTRIP_TYPE_TRANSITION) {
 			CLAMP(value, data->prev->start + NLASTRIP_MIN_LEN_THRESH, data->end - NLASTRIP_MIN_LEN_THRESH);
 			
-			/* readjust the transition to stick to the endpoints of the action-clips */
+			/* re-adjust the transition to stick to the endpoints of the action-clips */
 			data->prev->end = value;
 		}
 		else {