Update nodes between rendering cause segmentation fault

u6046121 — Wed, 13 Dec 2023 21:55:43 GMT

When reading the official example for arnold python api, I notice that the example deletes all relevant nodes before replacing them with the new ones. I was wondering if it is possible to just update the parameters of those nodes between frames using `AiNodeSetXXX`? (However, a segmentation fault is generated in this process, I do not know whether this is the correct way to do so)

A minimum working example:

#include <ai.h> #include <string> #include <vector> #include <iostream> #include <algorithm> #include <filesystem> namespace fs = std::filesystem; int main() { const fs::path ass_path = "test.ass"; AiBegin(); auto universe = AiUniverse(); auto session = AiRenderSession(universe, AI_SESSION_BATCH); auto load_ass_param = AiParamValueMap(); AiParamValueMapSetInt(load_ass_param, AtString("mask"), AI_NODE_ALL); AiSceneLoad (universe, ass_path.c_str(), load_ass_param); AiMsgInfo("Finish rendering"); /* preprocess */ AiRender(session); AtArray* vlist = AiArrayAllocate(8, 1, AI_TYPE_VECTOR); AiArraySetVec(vlist, 0, AtVector(0.200000003, -0.200000003, 0.200000003)); AiArraySetVec(vlist, 1, AtVector(0.200000003, -0.200000003, -0.200000003)); AiArraySetVec(vlist, 2, AtVector(-0.200000003, -0.200000003, 0.200000003)); AiArraySetVec(vlist, 3, AtVector(-0.200000003, -0.200000003, -0.200000003)); AiArraySetVec(vlist, 4, AtVector(0.200000003, 0.200000003, 0.200000003)); AiArraySetVec(vlist, 5, AtVector(0.200000003, 0.200000003, -0.200000003)); AiArraySetVec(vlist, 6, AtVector(-0.200000003, 0.200000003, 0.200000003)); AiArraySetVec(vlist, 7, AtVector(-0.200000003, 0.200000003, -0.200000003)); auto node = AiNodeLookUpByName(universe, AtString("/cube:Mesh/cube:MeshShape")); AiNodeSetArray(node, AtString("vlist"), vlist); // auto new_node = AiNodeClone(node); // AiNodeSetArray(new_node, AtString("vlist"), vlist); // AiNodeReplace(node, new_node, true); AiRender(session); AiMsgInfo("Finish rendering"); AiRenderSessionDestroy(session); AiUniverseDestroy(universe); AiEnd(); return 0; }

And my test.ass is:

### exported: Wed Dec 13 14:34:47 2023 ### from: Arnold 7.2.4.1 [1fee86c4] linux x86_64 clang-15.0.7 oiio-2.4.1 osl-1.12.9 vdb-7.1.1 adlsdk-7.4.2.47 clmhub-3.1.1.43 rlm-14.2.5 optix-6.6.0 2023/10/17 03:09:19 ### host app: MtoA 5.3.4.1 4d32feb2 (fix-5.3.4) Maya 2024 ### user: hansljy ### render_layer: defaultRenderLayer ### bounds: -0.2 -0.2 -0.2 0.2 0.2 0.2 ### meters_per_unit: 0.010000 options { AA_samples 3 AA_seed 300 outputs "RGBA RGBA defaultArnoldFilter/gaussian_filter defaultArnoldDriver/driver_exr.RGBA" xres 960 yres 540 texture_per_file_stats on texture_searchpath "/home/hansljy/maya/projects/textures/sourceimages" texture_automip off camera "/persp/perspShape" color_manager "defaultColorMgtGlobals" meters_per_unit 0.xxx-xxxxxxxx frame 300 procedural_searchpath "/home/hansljy/maya/projects/textures/" GI_diffuse_depth 1 GI_specular_depth 1 GI_transmission_depth 8 declare render_layer constant STRING render_layer "defaultRenderLayer" enable_dependency_graph true } gaussian_filter { name defaultArnoldFilter/gaussian_filter } driver_exr { name defaultArnoldDriver/driver_exr.RGBA filename "/home/hansljy/maya/projects/textures/images/untitled.exr" color_space "" } color_manager_ocio { name defaultColorMgtGlobals config "/usr/autodesk/maya/resources/OCIO-configs/Maya2022-default/config.ocio" color_space_linear "ACEScg" } persp_camera { name /persp/perspShape matrix 0.719401479 0.694594502 0 0 -0.320911646 0.332372785 0.886873186 0 0.616017222 -0.638017893 0.462012947 0 6.23699188 -6.45974159 4.67774391 1 near_clip 0.100000001 far_clip 10000 shutter_start 0 shutter_end 0 shutter_type "box" rolling_shutter "off" rolling_shutter_duration 0 motion_start 0 motion_end 0 exposure 0 fov 54.4322243 uv_remap 0 0 0 1 declare dcc_name constant STRING dcc_name "perspShape" } polymesh { name /cube:Mesh/cube:MeshShape visibility 255 sidedness 255 matrix 1 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 shader "standardSurface1" id 3745223389 nsides 12 1 UINT 3 3 3 3 3 3 3 3 3 3 3 3 vidxs 36 1 UINT 4 2 0 2 7 3 6 5 7 1 7 5 0 3 1 4 1 5 4 6 2 2 6 7 6 4 5 1 3 7 0 2 3 4 0 1 nidxs 36 1 UINT 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 vlist 8 1 VECTOR 0.200000003 -0.200000003 0.200000003 0.200000003 -0.200000003 -0.200000003 -0.200000003 -0.200000003 0.200000003 -0.200000003 -0.200000003 -0.200000003 0.200000003 0.200000003 0.200000003 0.200000003 0.200000003 -0.200000003 -0.200000003 0.200000003 0.200000003 -0.200000003 0.200000003 -0.200000003 nlist 36 1 VECTOR 0 0 1 0 0 1 0 0 1 -1 0 0 -1 0 0 -1 0 0 0 1 0 0 1 0 0 1 0 0 0 -1 0 0 -1 0 0 -1 0 -1 0 0 -1 0 0 -1 0 1 0 0 1 0 0 1 0 0 0 0 1 0 0 1 0 0 1 -1 0 0 -1 0 0 -1 0 0 0 1 0 0 1 0 0 1 0 0 0 -1 0 0 -1 0 0 -1 0 -1 0 0 -1 0 0 -1 0 1 0 0 1 0 0 1 0 0 smoothing on disp_padding 0 disp_height 1 disp_zero_value 0 disp_autobump off autobump_visibility 1 step_size 0 volume_padding 0 declare dcc_name constant STRING dcc_name "cube:MeshShape" } standard_surface { name standardSurface1 base_color 0.400000006 0.400000006 0.400000006 specular_roughness 0.5 transmit_aovs on normal 1 1 1 tangent 1 1 1 }

The program will crash on the second render call:

00:00:00 129MB | [ass] loading test.ass ... 00:00:00 129MB | [ass] read 3212 bytes, 7 nodes in 0:00.00 00:00:00 129MB | Finish rendering 00:00:00 227MB | parameter vlist on /cube:Mesh/cube:MeshShape was modified - reinitializing node [1] 138736 segmentation fault (core dumped) ./test

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Update nodes between rendering cause segmentation fault