Walk Navigation fails to use gravity with intersecting objects #47838

New Issue

Alex · 2016-03-18T13:52:26+01:00

Alex commented

2016-03-18 13:52:26 +01:00

System Information
Intel Core i7, 8 Gb RAM, AMD Radeon HD 7700
Windows 7 x64

Blender Version
Broken: 2.77 cc12fc1
Worked: 2.76b f337fea

Short description of error
Walk Navigation fails to use gravity with intersecting objects

Exact steps for others to reproduce the error
This bug took me more than two weeks to separate the exact reproducible case so please take a look at the attached Blend file: open the file, activate View -> Navigation -> Walk Navigation and teleport to the selected (new) plane. Activate gravity by pressing "G" and walk towards the next (old) plane:

In 2.76 you will eventually step on the old plane and go up just as expected.
In 2.77 you will walk through it instead of going up. Sometimes this doesn’t happen right away so you’ll just have to walk across the intersection a couple of times.
Just in case I’ve tried to add Solidify modifier and it didn’t help and later I was able to reproduce the same case with squashed cubes so it happens on solid objects as well.

If you want to reproduce the case itself, here are the steps to do it:

Open Blender, remove the default Cube and add a single Plane.
Scale that plane by regular scaling so it will be big enough to walk on (something like 20x20 should be enough) and apply the scale. (I'm not sure, but it looks like that scale is not the issue here.)
Enter Edit Mode, select the right edge and raise it to create a slope. Exit Edit Mode.
Create another plane by adding another primitive or by duplicating the first one. (It looks like that the key point here is to have a new object.)
Enter Edit Mode on the second plane and raise the left edge so both planes will become intersected somewhere. Exit Edit Mode. (The key point here is that planes are intersecting.)
Use View -> Navigation -> Walk Navigation and move or teleport to the first (old) plane. Activate gravity by pressing "G" and try to walk from one plane to another a couple of times.

The whole thing proved to be a problem for level design because you won’t be able to walk through your level if some of its parts are intersecting. This is not a major bug, but it doesn’t happen in 2.76 and it may indicate a problem somewhere else so I really hope that it will be fixed.
WalkModeBug.blend

**System Information** Intel Core i7, 8 Gb RAM, AMD Radeon HD 7700 Windows 7 x64 **Blender Version** Broken: 2.77 cc12fc1 Worked: 2.76b f337fea **Short description of error** Walk Navigation fails to use gravity with intersecting objects **Exact steps for others to reproduce the error** This bug took me more than two weeks to separate the exact reproducible case so please take a look at the attached Blend file: open the file, activate View -> Navigation -> Walk Navigation and teleport to the selected (new) plane. Activate gravity by pressing "G" and walk towards the next (old) plane: 1. In 2.76 you will eventually step on the old plane and go up just as expected. 2. In 2.77 you will walk through it instead of going up. Sometimes this doesn’t happen right away so you’ll just have to walk across the intersection a couple of times. Just in case I’ve tried to add Solidify modifier and it didn’t help and later I was able to reproduce the same case with squashed cubes so it happens on solid objects as well. If you want to reproduce the case itself, here are the steps to do it: 1. Open Blender, remove the default Cube and add a single Plane. 2. Scale that plane by regular scaling so it will be big enough to walk on (something like 20x20 should be enough) and apply the scale. (I'm not sure, but it looks like that scale is not the issue here.) 3. Enter Edit Mode, select the right edge and raise it to create a slope. Exit Edit Mode. 4. Create another plane by adding another primitive or by duplicating the first one. (It looks like that the key point here is to have a new object.) 5. Enter Edit Mode on the second plane and raise the left edge so both planes will become intersected somewhere. Exit Edit Mode. (The key point here is that planes are intersecting.) 6. Use View -> Navigation -> Walk Navigation and move or teleport to the first (old) plane. Activate gravity by pressing "G" and try to walk from one plane to another a couple of times. The whole thing proved to be a problem for level design because you won’t be able to walk through your level if some of its parts are intersecting. This is not a major bug, but it doesn’t happen in 2.76 and it may indicate a problem somewhere else so I really hope that it will be fixed. [WalkModeBug.blend](https://archive.blender.org/developer/F296741/WalkModeBug.blend)

Alex commented

2016-03-18 13:52:26 +01:00

Changed status to: 'Open'

Alex commented

2016-03-18 13:52:26 +01:00

Added subscriber: @SpectreFirst

NikoLeopold commented

2016-03-19 01:14:27 +01:00

Added subscriber: @NikoLeopold

Sergey Sharybin commented

2016-03-22 16:57:50 +01:00

Added subscriber: @Sergey

Bastien Montagne was assigned by Sergey Sharybin

2016-03-22 16:57:50 +01:00

Sergey Sharybin commented

2016-03-22 16:57:50 +01:00

Caused by 3ad0344.

Caused by 3ad0344.

Bastien Montagne was unassigned by Germano Cavalcante

2016-03-22 19:39:27 +01:00

Germano Cavalcante self-assigned this 2016-03-22 19:39:27 +01:00

Germano Cavalcante commented

2016-03-22 19:39:27 +01:00

Added subscriber: @mont29

Germano Cavalcante commented

2016-03-22 20:49:16 +01:00

Here is a possible solution.

diff --git a/source/blender/editors/transform/transform_snap.c b/source/blender/editors/transform/transform_snap.c
index 3622012..26c2427 100644
--- a/source/blender/editors/transform/transform_snap.c
+++ b/source/blender/editors/transform/transform_snap.c
@@ -1574,7 +1574,7 @@ static bool snapDerivedMesh(
                                        bb = &bb_temp;
                                }
 
-                               len_diff = local_depth;
+                               len_diff = BVH_RAYCAST_DIST_MAX;
                                if (!BKE_boundbox_ray_hit_check(bb, ray_start_local, ray_normal_local, &len_diff)) {
                                        return retval;
                                }

When the ray is inside the bound the box, the lamda of "BKE_boundbox_ray_hit_check" can be greater than the depth of the object. :/

Here is a possible solution. ``` diff --git a/source/blender/editors/transform/transform_snap.c b/source/blender/editors/transform/transform_snap.c index 3622012..26c2427 100644 --- a/source/blender/editors/transform/transform_snap.c +++ b/source/blender/editors/transform/transform_snap.c @@ -1574,7 +1574,7 @@ static bool snapDerivedMesh( bb = &bb_temp; } - len_diff = local_depth; + len_diff = BVH_RAYCAST_DIST_MAX; if (!BKE_boundbox_ray_hit_check(bb, ray_start_local, ray_normal_local, &len_diff)) { return retval; } ``` When the ray is inside the bound the box, the lamda of "BKE_boundbox_ray_hit_check" can be greater than the depth of the object. :/

Germano Cavalcante removed their assignment 2016-03-22 20:56:13 +01:00

Bastien Montagne was assigned by Germano Cavalcante

2016-03-22 20:56:13 +01:00

Germano Cavalcante commented

2016-03-22 20:56:13 +01:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2016-03-22 21:43:21 +01:00

Another solution is to use "isect_ray_aabb_v3", it is much more efficient, allows depth negative and still ignores BoundBox that are fully behind the ray.

However it is not very accurate.

diff --git a/source/blender/editors/transform/transform_snap.c b/source/blender/editors/transform/transform_snap.c
index 3622012..1a3033a 100644
--- a/source/blender/editors/transform/transform_snap.c
+++ b/source/blender/editors/transform/transform_snap.c
@@ -1574,8 +1574,12 @@ static bool snapDerivedMesh(
 					bb = &bb_temp;
 				}
 
-				len_diff = local_depth;
-				if (!BKE_boundbox_ray_hit_check(bb, ray_start_local, ray_normal_local, &len_diff)) {
+				//len_diff = local_depth
+				/* BKE_boundbox_ray_hit_check does not accept negative values for the lambda */
+				struct IsectRayAABB_Precalc data;
+				isect_ray_aabb_v3_precalc(&data, ray_start_local, ray_normal_local);
+				if (!isect_ray_aabb_v3(&data, bb->vec[0], bb->vec[6], &len_diff) ||
+				   (len_diff > local_depth)) {
 					return retval;
 				}
 				need_ray_start_correction_init = false;

Another solution is to use "isect_ray_aabb_v3", it is much more efficient, allows depth negative and still ignores BoundBox that are fully behind the ray. However it is not very accurate. ``` diff --git a/source/blender/editors/transform/transform_snap.c b/source/blender/editors/transform/transform_snap.c index 3622012..1a3033a 100644 --- a/source/blender/editors/transform/transform_snap.c +++ b/source/blender/editors/transform/transform_snap.c @@ -1574,8 +1574,12 @@ static bool snapDerivedMesh( bb = &bb_temp; } - len_diff = local_depth; - if (!BKE_boundbox_ray_hit_check(bb, ray_start_local, ray_normal_local, &len_diff)) { + //len_diff = local_depth + /* BKE_boundbox_ray_hit_check does not accept negative values for the lambda */ + struct IsectRayAABB_Precalc data; + isect_ray_aabb_v3_precalc(&data, ray_start_local, ray_normal_local); + if (!isect_ray_aabb_v3(&data, bb->vec[0], bb->vec[6], &len_diff) || + (len_diff > local_depth)) { return retval; } need_ray_start_correction_init = false; ```

Campbell Barton commented

2016-03-24 07:51:54 +01:00

Changed status from 'Open' to: 'Resolved'

Campbell Barton closed this issue

2016-03-24 07:51:54 +01:00

blender-admin commented

2016-03-24 07:52:31 +01:00

This issue was referenced by 75849b099f

This issue was referenced by 75849b099f28cfcecd578122e2bfd227468eacf5

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Walk Navigation fails to use gravity with intersecting objects #47838