From cde858ae98a5bcc214cabae0890a09b5b41e9909 Mon Sep 17 00:00:00 2001 From: Stefan Werner Date: Wed, 20 Jan 2021 11:17:32 +0100 Subject: Particles: Fixed thread work size calculation. Dividing the workload by number of tasks in float is imprecise and lead in some cases to particles not being calculated at all (example: 20000 particles, 144 tasks). Switching this calculation to integer makes sure we don't lose count. Differential Revision: https://developer.blender.org/D10157 --- source/blender/blenkernel/intern/particle_system.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/source/blender/blenkernel/intern/particle_system.c b/source/blender/blenkernel/intern/particle_system.c index b3472bfe716..615c4350fe4 100644 --- a/source/blender/blenkernel/intern/particle_system.c +++ b/source/blender/blenkernel/intern/particle_system.c @@ -476,20 +476,24 @@ void psys_tasks_create(ParticleThreadContext *ctx, { ParticleTask *tasks; int numtasks = min_ii(BLI_system_thread_count() * 4, endpart - startpart); - float particles_per_task = (float)(endpart - startpart) / (float)numtasks, p, pnext; - int i; + int particles_per_task = numtasks > 0 ? (endpart - startpart) / numtasks : 0; + int remainder = numtasks > 0 ? (endpart - startpart) - particles_per_task * numtasks : 0; tasks = MEM_callocN(sizeof(ParticleTask) * numtasks, "ParticleThread"); *r_numtasks = numtasks; *r_tasks = tasks; - p = (float)startpart; - for (i = 0; i < numtasks; i++, p = pnext) { - pnext = p + particles_per_task; - + int p = startpart; + for (int i = 0; i < numtasks; i++) { tasks[i].ctx = ctx; - tasks[i].begin = (int)p; - tasks[i].end = min_ii((int)pnext, endpart); + tasks[i].begin = p; + p = p + particles_per_task + (i < remainder ? 1 : 0); + tasks[i].end = p; + } + + /* Verify that all particles are accounted for. */ + if (numtasks > 0) { + BLI_assert(tasks[numtasks - 1].end == endpart); } } -- cgit v1.2.3