Weather: rain falls inside under a sloped roof (about a metre past the roof surface)

sky_line commented

2026-10-27 12:10:08 +00:00

Owner

Rain falls inside a closed attic, about a metre in from the roof: the streaks appear under the sloped roof and fall onto the floor near the walls and in the middle of the room (screenshot below; dev build 2026-10-27, parcel rain). The same build shows streaks falling through a lower room's walls and floor as well.

What keeps rain out today: the weather occlusion map (#783, RenderVKWeatherOcclusion 1): a top-down depth map around the camera (coarse cascade of about half-metre texels plus the near cascade, RenderVKWeatherNearCascade 1, refreshed every RenderVKWeatherOcclusionInterval = 30 frames or on a cell change). The roof here is a steep, thin, sloped surface, so a streak can be about a metre inside it and still be let through.

Suspects to check:

Texel resolution or depth bias at a steep slope: under a 45-60 degree roof, half a metre horizontally is up to a metre vertically, so a coarse texel or a soft edge filter reads 'open sky' for points under the roof.
Which point of the streak is tested: the head, the tail, or a point offset along the wind.
Whether the roof faces are in the map at all: single-sided or back-face-culled faces seen from above, or alpha-masked faces.

Check with the occlusion debug view if there is one, else dump the map, and compare it with the roof's height in this room.

Test: in this attic (and a room under a pitched roof generally) with steady rain, no streak appears below the roof; rain still falls right up to the eaves outside.

Rain falls inside a closed attic, about a metre in from the roof: the streaks appear under the sloped roof and fall onto the floor near the walls and in the middle of the room (screenshot below; dev build 2026-10-27, parcel rain). The same build shows streaks falling through a lower room's walls and floor as well. **What keeps rain out today:** the weather occlusion map (#783, `RenderVKWeatherOcclusion` 1): a top-down depth map around the camera (coarse cascade of about half-metre texels plus the near cascade, `RenderVKWeatherNearCascade` 1, refreshed every `RenderVKWeatherOcclusionInterval` = 30 frames or on a cell change). The roof here is a steep, thin, sloped surface, so a streak can be about a metre inside it and still be let through. **Suspects to check:** - **Texel resolution or depth bias** at a steep slope: under a 45-60 degree roof, half a metre horizontally is up to a metre vertically, so a coarse texel or a soft edge filter reads 'open sky' for points under the roof. - **Which point of the streak is tested:** the head, the tail, or a point offset along the wind. - **Whether the roof faces are in the map at all:** single-sided or back-face-culled faces seen from above, or alpha-masked faces. Check with the occlusion debug view if there is one, else dump the map, and compare it with the roof's height in this room. **Test:** in this attic (and a room under a pitched roof generally) with steady rain, no streak appears below the roof; rain still falls right up to the eaves outside. ![attic rain](https://git.slipstreamviewer.org/attachments/7ae8761f-8144-4d28-ab88-a03db280a25f)

attic_rain.png

9.9 MiB

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2026-10-27 16:28:13 +00:00

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2026-10-27 17:47:37 +00:00

TheSlowly referenced this issue

2026-10-27 18:28:53 +00:00

Weather: glass roofs let rain and snow through (alpha-blend casters below 0.5 count as open sky) #1159

~~TheSlowly referenced this issue 2026-10-27 18:46:39 +00:00~~

#1145 Weather: rain no longer falls inside under a sloped roof #1163

TheSlowly referenced this issue

2026-10-27 20:23:47 +00:00

#1145 Weather: rain no longer falls inside under a sloped roof #1163

sky_line referenced this issue from a commit

2026-10-27 20:23:48 +00:00

#1145 Weather: rain no longer falls inside under a sloped roof

TheSlowly referenced this issue

2026-10-27 21:03:00 +00:00

Static prims flagged as moving objects by float noise: rain and snow inside buildings, snow coat indoors #1166

TheSlowly referenced this issue

2026-10-27 21:03:15 +00:00

#1166 Static prims no longer flagged as moving objects by float noise (rain / snow inside buildings) #1167

sky_line referenced this issue from a commit

2026-10-27 22:03:58 +00:00

#1145 Weather: rain no longer falls inside under a sloped roof

TheSlowly commented

2026-10-27 22:10:04 +00:00

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Fixed in main by ae2b972c16.

Fixed in main by ae2b972c16.

TheSlowly closed this issue

2026-10-27 22:10:04 +00:00

sky_line commented

2026-10-27 22:43:11 +00:00

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Reopened: 1.4.5 has the first part (rain no longer falls far inside), but rain still reaches inside under a sloped roof in strong wind. Follow-ups on dev: the weather map now draws without the depth bias, and the fine map is centred so a raised room (an attic) stays on it under a strong wind tilt. Testing continues.

sky_line reopened this issue

2026-10-27 22:43:11 +00:00

sky_line referenced this issue from a commit

2026-10-27 22:56:29 +00:00

#1145 Weather: rain no longer falls inside under a sloped roof

sky_line referenced this issue

2026-10-28 16:10:46 +00:00

Weather occlusion: untilted heightfield + per-drop direction march (rain shadow follows the actual rain) #1198

sky_line referenced this issue from a commit

2026-10-28 16:13:18 +00:00

Weather: run-off drips under cover are gone once they leave their edge (#1145)

sky_line referenced this issue from a commit