Particles spawn scattered around the prim instead of at its centre (follow-source / target-linear) #173

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opened 2026-09-29 19:11:14 +00:00 by sky_line · 0 comments

sky_line commented

2026-09-29 19:11:14 +00:00

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Reported by a user: particles that should all spawn at the centre of the prim spawned at random positions around it. Firestorm draws them correctly.

Cause: LLViewerPartSourceScript::update zeroes the burst radius for particles with PSYS_PART_FOLLOW_SRC_MASK or PSYS_PART_TARGET_LINEAR_MASK (SVC-193, VWR-717), so they start exactly at the source. The Vulkan GPU emitter was given the raw PSYS_SRC_BURST_RADIUS, and placed them on a sphere of that radius around the prim.

Fixed in c05cd59eb1 (verified in-world). The same change also matched two more LL spawn rules in clean_particle_emit.comp:

the DROP pattern takes precedence over the other pattern bits;
sources using the deprecated angle parameters (no PSYS_PART_USE_NEW_ANGLE) get LL's extra rotation by the outer angle.

Related: #35 (particle parity).

**Reported by a user:** particles that should all spawn at the centre of the prim spawned at random positions around it. Firestorm draws them correctly. **Cause:** `LLViewerPartSourceScript::update` zeroes the burst radius for particles with `PSYS_PART_FOLLOW_SRC_MASK` or `PSYS_PART_TARGET_LINEAR_MASK` (SVC-193, VWR-717), so they start exactly at the source. The Vulkan GPU emitter was given the raw `PSYS_SRC_BURST_RADIUS`, and placed them on a sphere of that radius around the prim. **Fixed in c05cd59eb1** (verified in-world). The same change also matched two more LL spawn rules in `clean_particle_emit.comp`: - the DROP pattern takes precedence over the other pattern bits; - sources using the deprecated angle parameters (no `PSYS_PART_USE_NEW_ANGLE`) get LL's extra rotation by the outer angle. Related: #35 (particle parity).

sky_line closed this issue

2026-09-29 19:11:15 +00:00

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sky_line/Slipstream#173

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