BNLNPPS · ggalgoczi · May 15, 2026 · May 15, 2026
diff --git a/.github/workflows/build-pull-request.yaml b/.github/workflows/build-pull-request.yaml
@@ -184,6 +184,7 @@ jobs:
           docker run --rm --gpus 'device=1' ${{ env.IMAGE_NAME }}:${{ env.IMAGE_TAG }} tests/test_opticks.sh
           docker run --rm --gpus 'device=1' ${{ env.IMAGE_NAME }}:${{ env.IMAGE_TAG }} tests/test_simg4ox.sh
           docker run --rm --gpus 'device=1' ${{ env.IMAGE_NAME }}:${{ env.IMAGE_TAG }} tests/test_GPURaytrace.sh
+          docker run --rm --gpus 'device=1' ${{ env.IMAGE_NAME }}:${{ env.IMAGE_TAG }} tests/test_triangulated.sh
           docker run --rm --gpus 'device=1' ${{ env.IMAGE_NAME }}:${{ env.IMAGE_TAG }} tests/test_GPUPhotonFileSource.sh
           docker run --rm --gpus 'device=1' ${{ env.IMAGE_NAME }}:${{ env.IMAGE_TAG }} tests/test_GPUPhotonSource_8x8SiPM.sh
           docker run --rm --gpus 'device=1' ${{ env.IMAGE_NAME }}:${{ env.IMAGE_TAG }} tests/test_wavelength_shifting.sh

diff --git a/CSGOptiX/PIP.cc b/CSGOptiX/PIP.cc
@@ -70,7 +70,7 @@ OptixPipelineCompileOptions PIP::CreatePipelineOptions(unsigned numPayloadValues
     pipeline_compile_options.numAttributeValues    = numAttributeValues ;
     pipeline_compile_options.exceptionFlags        = OPT::ExceptionFlags( CreatePipelineOptions_exceptionFlags )  ;
     pipeline_compile_options.pipelineLaunchParamsVariableName = "params";
-    pipeline_compile_options.usesPrimitiveTypeFlags = OPTIX_PRIMITIVE_TYPE_FLAGS_CUSTOM ;  
+    pipeline_compile_options.usesPrimitiveTypeFlags = OPTIX_PRIMITIVE_TYPE_FLAGS_CUSTOM | OPTIX_PRIMITIVE_TYPE_FLAGS_TRIANGLE;
 
     return pipeline_compile_options ;  
 }
@@ -410,40 +410,62 @@ PIP::createHitgroupPG
 
 void PIP::createHitgroupPG()
 {
-    OptixProgramGroupDesc desc = {};
-    desc.kind = OPTIX_PROGRAM_GROUP_KIND_HITGROUP;
-
-    desc.hitgroup.moduleIS            = module ;
-    desc.hitgroup.entryFunctionNameIS =  IS ;
-
-    desc.hitgroup.moduleCH            = module  ; 
-    desc.hitgroup.entryFunctionNameCH = CH ;
-
-    desc.hitgroup.moduleAH            = nullptr ;
-    desc.hitgroup.entryFunctionNameAH = nullptr ; 
-
-    size_t sizeof_log = 0 ; 
-    char log[2048]; 
-    unsigned num_program_groups = 1 ; 
-
-
-    OPTIX_CHECK_LOG( optixProgramGroupCreate(
-                Ctx::context,
-                &desc,
-                num_program_groups,
-                &program_group_options,
-                log,
-                &sizeof_log,
-                &hitgroup_pg
-                ) );
-
-    if(sizeof_log > 0) std::cout << log << std::endl ; 
-    assert( sizeof_log == 0); 
+    size_t   sizeof_log = 0;
+    char     log[2048];
+    unsigned num_program_groups = 1;
+
+    // analytic (custom primitive) hitgroup: custom IS + CH
+    OptixProgramGroupDesc desc_ana = {};
+    desc_ana.kind = OPTIX_PROGRAM_GROUP_KIND_HITGROUP;
+    desc_ana.hitgroup.moduleIS = module;
+    desc_ana.hitgroup.entryFunctionNameIS = IS;
+    desc_ana.hitgroup.moduleCH = module;
+    desc_ana.hitgroup.entryFunctionNameCH = CH;
+    desc_ana.hitgroup.moduleAH = nullptr;
+    desc_ana.hitgroup.entryFunctionNameAH = nullptr;
+
+    OPTIX_CHECK_LOG(optixProgramGroupCreate(
+        Ctx::context,
+        &desc_ana,
+        num_program_groups,
+        &program_group_options,
+        log,
+        &sizeof_log,
+        &hitgroup_pg));
+
+    if (sizeof_log > 0)
+        std::cout << log << std::endl;
+    assert(sizeof_log == 0);
+
+    // triangle hitgroup: builtin IS (must be null) + CH
+    sizeof_log = 0;
+    OptixProgramGroupDesc desc_tri = {};
+    desc_tri.kind = OPTIX_PROGRAM_GROUP_KIND_HITGROUP;
+    desc_tri.hitgroup.moduleIS = nullptr;
+    desc_tri.hitgroup.entryFunctionNameIS = nullptr;
+    desc_tri.hitgroup.moduleCH = module;
+    desc_tri.hitgroup.entryFunctionNameCH = CH;
+    desc_tri.hitgroup.moduleAH = nullptr;
+    desc_tri.hitgroup.entryFunctionNameAH = nullptr;
+
+    OPTIX_CHECK_LOG(optixProgramGroupCreate(
+        Ctx::context,
+        &desc_tri,
+        num_program_groups,
+        &program_group_options,
+        log,
+        &sizeof_log,
+        &hitgroup_pg_tri));
+
+    if (sizeof_log > 0)
+        std::cout << log << std::endl;
+    assert(sizeof_log == 0);
 }
 
 void PIP::destroyHitgroupPG()
 {
     OPTIX_CHECK( optixProgramGroupDestroy( hitgroup_pg ) );
+    OPTIX_CHECK(optixProgramGroupDestroy(hitgroup_pg_tri));
 }
 
 
@@ -482,7 +504,7 @@ std::string PIP::Desc_PipelineLinkOptions(const OptixPipelineLinkOptions& pipeli
 
 void PIP::linkPipeline(unsigned max_trace_depth)
 {
-    OptixProgramGroup program_groups[] = { raygen_pg, miss_pg, hitgroup_pg };
+    OptixProgramGroup program_groups[] = {raygen_pg, miss_pg, hitgroup_pg, hitgroup_pg_tri};
 
     OptixPipelineLinkOptions pipeline_link_options = {};
     pipeline_link_options.maxTraceDepth          = max_trace_depth ;
@@ -550,13 +572,15 @@ void PIP::configureStack()
     OptixStackSizes stackSizes = {};
 
 #if OPTIX_VERSION <= 70600
-    OPTIX_CHECK( optixUtilAccumulateStackSizes( raygen_pg,   &stackSizes ) ); 
-    OPTIX_CHECK( optixUtilAccumulateStackSizes( miss_pg,     &stackSizes ) ); 
-    OPTIX_CHECK( optixUtilAccumulateStackSizes( hitgroup_pg, &stackSizes ) ); 
+    OPTIX_CHECK(optixUtilAccumulateStackSizes(raygen_pg, &stackSizes));
+    OPTIX_CHECK(optixUtilAccumulateStackSizes(miss_pg, &stackSizes));
+    OPTIX_CHECK(optixUtilAccumulateStackSizes(hitgroup_pg, &stackSizes));
+    OPTIX_CHECK(optixUtilAccumulateStackSizes(hitgroup_pg_tri, &stackSizes));
 #else
-    OPTIX_CHECK( optixUtilAccumulateStackSizes( raygen_pg,   &stackSizes, pipeline ) ); 
-    OPTIX_CHECK( optixUtilAccumulateStackSizes( miss_pg,     &stackSizes, pipeline ) ); 
-    OPTIX_CHECK( optixUtilAccumulateStackSizes( hitgroup_pg, &stackSizes, pipeline ) ); 
+    OPTIX_CHECK(optixUtilAccumulateStackSizes(raygen_pg, &stackSizes, pipeline));
+    OPTIX_CHECK(optixUtilAccumulateStackSizes(miss_pg, &stackSizes, pipeline));
+    OPTIX_CHECK(optixUtilAccumulateStackSizes(hitgroup_pg, &stackSizes, pipeline));
+    OPTIX_CHECK(optixUtilAccumulateStackSizes(hitgroup_pg_tri, &stackSizes, pipeline));
 #endif
 
 

diff --git a/CSGOptiX/PIP.h b/CSGOptiX/PIP.h
@@ -31,9 +31,10 @@ struct PIP
 
     OptixModule module = nullptr;
 
-    OptixProgramGroup raygen_pg   = nullptr;
-    OptixProgramGroup miss_pg     = nullptr;
-    OptixProgramGroup hitgroup_pg = nullptr;
+    OptixProgramGroup raygen_pg = nullptr;
+    OptixProgramGroup miss_pg = nullptr;
+    OptixProgramGroup hitgroup_pg = nullptr;     // analytic (custom primitive): IS + CH
+    OptixProgramGroup hitgroup_pg_tri = nullptr; // triangle: CH only (builtin IS)
 
     OptixPipeline pipeline = nullptr;
 

diff --git a/CSGOptiX/SBT.cc b/CSGOptiX/SBT.cc
@@ -899,9 +899,6 @@ void SBT::createHitgroup()
     hitgroup = new HitGroup[tot_rec] ;
     HitGroup* hg = hitgroup ;
 
-    for(unsigned i=0 ; i < tot_rec ; i++)   // pack headers CPU side
-         OPTIX_CHECK( optixSbtRecordPackHeader( pip->hitgroup_pg, hitgroup + i ) );
-
     unsigned sbt_offset = 0 ;
 
     for(IT it=vgas.begin() ; it !=vgas.end() ; it++)
@@ -974,6 +971,9 @@ void SBT::createHitgroup()
                 int boundary = foundry->getPrimBoundary_(prim);
                 assert( boundary > -1 );
 
+                OptixProgramGroup record_pg = trimesh ? pip->hitgroup_pg_tri : pip->hitgroup_pg;
+                OPTIX_CHECK(optixSbtRecordPackHeader(record_pg, hg));
+
                 if( trimesh == false )  // analytic
                 {
                     setPrimData( hg->data.prim, prim );  // copy numNode, nodeOffset from CSGPrim into hg->data

diff --git a/tests/test_triangulated.sh b/tests/test_triangulated.sh
@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+# Forcing triangulation of a box-shaped solid (here G4_WATER_solid in
+# opticks_raindrop.gdml) must produce bit-identical GPU hit counts vs
+# the analytic CSG path: a G4Box triangulates to 12 flat triangles that
+# coincide with the analytic surface, so the only thing this test can
+# detect breaking is the triangulated-GAS wiring (pipeline flags, second
+# hitgroup PG, per-record SBT header packing).
+set -e
+
+GDML="$OPTICKS_HOME/tests/geom/opticks_raindrop.gdml"
+MAC="$OPTICKS_HOME/tests/run.mac"
+SEED=42
+
+ANA=$(USER=ci GEOM=triraindrop_ana \
+    GPURaytrace -g "$GDML" -m "$MAC" -s "$SEED" 2>&1 \
+    | awk '/Opticks: NumHits:/ {print $NF}')
+
+TRI=$(USER=ci GEOM=triraindrop_tri stree__force_triangulate_solid=G4_WATER_solid \
+    GPURaytrace -g "$GDML" -m "$MAC" -s "$SEED" 2>&1 \
+    | awk '/Opticks: NumHits:/ {print $NF}')
+
+echo "analytic=$ANA triangulated=$TRI"
+[ -n "$ANA" ] && [ "$ANA" = "$TRI" ] || { echo "FAILED: triangulated($TRI) != analytic($ANA)"; exit 1; }
+echo "PASSED"