Commit: 0079460dc79a6c4798ec41e86550d8f0882ed313 Author: Chris Blackbourn Date: Fri Dec 16 17:22:41 2022 +1300 Branches: master https://developer.blender.org/rB0079460dc79a6c4798ec41e86550d8f0882ed313
Fix T102923: replace zero check with epsilons with uv constrain to bounds Small roundoff errors during UV editing can sometimes occur, most likely due to so-called "catastrophic cancellation". Here we set a tolerance around zero when using Constrain-To-Bounds and UV Scaling. The tolerance is set at one quarter of a texel, on a 65536 x 65536 texture. TODO: If this fix holds, we should formalize the tolerance into the UV editing subsystem, perhaps as a helper function, and investigate where else it needs to be applied. Differential Revision: https://developer.blender.org/D16702 =================================================================== M source/blender/editors/transform/transform_mode_resize.c =================================================================== diff --git a/source/blender/editors/transform/transform_mode_resize.c b/source/blender/editors/transform/transform_mode_resize.c index 70599c3577c..4e671768721 100644 --- a/source/blender/editors/transform/transform_mode_resize.c +++ b/source/blender/editors/transform/transform_mode_resize.c @@ -95,9 +95,14 @@ static void constrain_scale_to_boundary(const float numerator, const float denominator, float *scale) { - if (denominator == 0.0f) { - /* The origin of the scale is on the edge of the boundary. */ - if (numerator < 0.0f) { + /* It's possible the numerator or denominator can be very close to zero due to so-called + * "catastrophic cancellation". See T102923 for an example. We use epsilon tests here to + * distinguish between genuine negative coordinates versus coordinates that should be rounded off + * to zero. */ + const float epsilon = 0.25f / 65536.0f; /* i.e. Quarter of a texel on a 65536 x 65536 texture. */ + if (fabsf(denominator) < epsilon) { + /* The origin of the scale is very near the edge of the boundary. */ + if (numerator < -epsilon) { /* Negative scale will wrap around and put us outside the boundary. */ *scale = 0.0f; /* Hold at the boundary instead. */ } _______________________________________________ Bf-blender-cvs mailing list Bf-blender-cvs@blender.org List details, subscription details or unsubscribe: https://lists.blender.org/mailman/listinfo/bf-blender-cvs
