OpenVDB Hello World

[Kalina]

I'm trying to figure out how to create an OpenVDB volume by writing out the voxels, to make a custom SOP.

The OpenVDB Hello World example goes something like this:

// Initialize the OpenVDB library. This must be called at least
// once per program and may safely be called multiple times.
openvdb::initialize();

// Create an empty floating-point grid with background value 0. 
openvdb::FloatGrid::Ptr grid = openvdb::FloatGrid::create();

// Get an accessor for coordinate-based access to voxels.
openvdb::FloatGrid::Accessor accessor = grid->getAccessor();

// Define a coordinate with signed indices.
openvdb::Coord xyz(5, 5, 5);

// Set the voxel value at (5, 5, 5) to 1.
accessor.setValue(xyz, 1.0);

But now how would I get this to work in Houdini in my "cookMySop()" function? How do I attach this grid to a GU_PrimVDB (or something) to actually create the OpenVDB primitive in Houdini? Could I get a Houdini-specific "Hello World" example?

 

Edited November 5, 2014 by Kalina

[edward]

Perhaps not quite so Hello World:

https://github.com/dreamworksanimation/openvdb/blob/master/openvdb_houdini/houdini/SOP_OpenVDB_Create.cc

 

But all you really need to look for in that file is the createNewGrid() function.

[Kalina]

Thanks, but that didn't get me very far. I now have:

openvdb::GridBase::Ptr grid = openvdb::FloatGrid::create();
GEO_PrimVDB* vdb = GU_PrimVDB::buildFromGrid((GU_Detail&)gdp, grid, NULL, "gridName");

which segfaults and crashes:

AP_Interface::coreDumpChaser(UTsignalHandlerArg) <libHoudiniUI.so>
AP_Interface::si_CrashHandler::chaser(UTsignalHandlerArg) <libHoudiniUI.so>
signalCallback(UTsignalHandlerArg) <libHoudiniUT.so>
UT_Signal::UT_ComboSignalHandler::operator()(int, siginfo*, void*) const <libHoudiniUT.so>
UT_Signal::processSignal(int, siginfo*, void*) <libHoudiniUT.so>
[0xf70e] <libpthread.so.0>
GA_PrimitiveFactory::lookupDefinition(GA_PrimitiveTypeId const&) const <libHoudiniGEO.so>
GA_PrimitiveFactory::create(GA_PrimitiveTypeId const&, GA_Detail&, long) const <libHoudiniGEO.so>
GEO_Detail::insertPrimitive(GA_PrimitiveTypeId const&, GEO_Primitive const*) <libHoudiniGEO.so>
GU_PrimVDB::build(GU_Detail*, bool) <libHoudiniGEO.so>
GU_PrimVDB::buildFromGridAdapter(GU_Detail&, void*, GEO_PrimVDB const*, char const*) <libHoudiniGEO.so>

Edited November 6, 2014 by Kalina

[edward]

gdp is a GU_Detail pointer, you should use *gdp to pass it as a reference.

[Kalina]

Thank you, I got it working!

openvdb::FloatGrid::Ptr grid = openvdb::FloatGrid::create();

openvdb::FloatGrid::Accessor accessor = grid->getAccessor();
openvdb::Coord xyz(5,5,5);
accessor.setValue(xyz, 1.0);
xyz.reset(0,0,0);
accessor.setValue(xyz, 1.0);

GU_PrimVDB* vdb = GU_PrimVDB::buildFromGrid((GU_Detail&)*gdp, grid, NULL, "gridName");

[Kalina]

I just updated to Houdini16, and all of a sudden this same little code snippet doesn't work anymore. Houdini crashes on the line:

GU_PrimVDB* vdb = GU_PrimVDB::buildFromGrid((GU_Detail&)*gdp, grid, NULL, "gridName");

...with no log or helpful error message, just:

undefined symbol: _ZN7openvdb11v3_3_0_sesi4math9TransformC1ERKSt10shared_ptrINS1_7MapBaseEE

Deciphering that with c++filt shows that it's complaining about:

openvdb::v3_3_0_sesi::math::Transform::Transform(std::shared_ptr<openvdb::v3_3_0_sesi::math::MapBase> const&)

...even though I'm not even using a transform. Any thoughts?

Edited April 11, 2017 by Kalina

[Kalina]

Here is the full problematic code:
 

SOP_Testing.C:
 

#include "SOP_Testing.h"

#include <UT/UT_DSOVersion.h>
#include <OP/OP_OperatorTable.h>
#include <OP/OP_AutoLockInputs.h>

using namespace AVL_Testing;

PRM_Template SOP_Testing::myTemplateList[] = { PRM_Template() };

void newSopOperator(OP_OperatorTable *table)
{
    OP_Operator *op;
    op = new OP_Operator("avl_testing", "Testing", SOP_Testing::myConstructor, SOP_Testing::myTemplateList, 0, 0, NULL, OP_FLAG_GENERATOR );
    table->addOperator(op);
}

OP_Node* SOP_Testing::myConstructor(OP_Network *net, const char *name, OP_Operator *op)
{
    return new SOP_Testing(net, name, op);
}
SOP_Testing::SOP_Testing(OP_Network *net, const char *name, OP_Operator *op): SOP_Node(net, name, op){}
SOP_Testing::~SOP_Testing() {}

OP_ERROR SOP_Testing::cookMySop(OP_Context &context)
{
    openvdb::FloatGrid::Ptr grid = openvdb::FloatGrid::create();
    openvdb::FloatGrid::Accessor accessor = grid->getAccessor();
    openvdb::Coord xyz(5,5,5);
    accessor.setValue(xyz, 1.0);
    xyz.reset(0,0,0);
    accessor.setValue(xyz, 1.0);
    GU_PrimVDB::buildFromGrid((GU_Detail&)*gdp, grid, NULL, "gridName");  // Crashes on this line! 
                                                                          // Complains about openvdb::v3_3_0_sesi::math::Transform::Transform(std::shared_ptr<openvdb::v3_3_0_sesi::math::MapBase> const&)

    return error();
}

SOP_Testing.h:
 

#ifndef __SOP_Testing_h__
#define __SOP_Testing_h__

#include <GU/GU_PrimVDB.h>
#include <SOP/SOP_Node.h>

namespace AVL_Testing {

class SOP_Testing : public SOP_Node
{
    public:
        static OP_Node *myConstructor(OP_Network*, const char *, OP_Operator *);
        static PRM_Template myTemplateList[];

    protected:
        SOP_Testing(OP_Network *net, const char *name, OP_Operator *op);
        virtual ~SOP_Testing();
        virtual OP_ERROR cookMySop(OP_Context &context);

    };
}

#endif

Makefile:

CXX=/share/apps/bin/gcc

HOU_VERSION = 16.0

DSONAME = SOP_Testing.so
LOCATION = ~/houdini${HOU_VERSION}/dso/

SOURCES = SOP_Testing.C

include $(HFS)/toolkit/makefiles/Makefile.gnu

OPTIMIZER = -g
HOUDINI_DSO_ERROR = 2

CPPFLAGS += -fPIC

install:
    mkdir -p ${LOCATION}
    cp ${DSONAME} ${LOCATION}

 

Edited April 11, 2017 by Kalina

[goldleaf]

What version of OpenVDB are you linking against, the one that ships with Houdini 16, or from Github? And there have been some HDK/OpenVDB changes in the logs; I'd try using 16.0.557 or later if you can.

[Kalina]

I'm using whatever came with Houdini16.

Should I be using a different one?

[edward]

You need to compile with -DOPENVDB_3_ABI_COMPATIBLE (ie. define OPENVDB_3_ABI_COMPATIBLE) when you build your HDK plugin. This was accidentally left out of hcustom in early builds and looks like it's missing in the shipped Makefiles still.

[edward]

Try adding this to your Makefile

THIRDPARTYDEFS += -DOPENVDB_3_ABI_COMPATIBLE

[Kalina]

Thanks, but that didn't help. The issue is still the same.

A bit more info that may be relevant, though: I am on CentOS 6, which comes pre-packaged with gcc4.4. You may notice that my Makefile points to

CXX=/share/apps/bin/gcc

...where I have gcc4.9.3, which I'm trying to use instead. Am I using the wrong gcc version, or pointing to it incorrectly?

[edward]

H16 requires gcc 4.8 or later. To be safe I think I would try gcc 4.8

[Kalina]

OK, I'll try downgrading from 4.9.3

Edited April 19, 2017 by Kalina

[Kalina]

Updating from Houdini 16.0.504.20 to 16.0.577 fixed the issue.

[edward]

I'm pretty sure that this link error:

undefined symbol: _ZN7openvdb11v3_3_0_sesi4math9TransformC1ERKSt10shared_ptrINS1_7MapBaseEE

is caused by not compiling everything with -DOPENVDB_3_ABI_COMPATIBLE. One of the differences when this is defined is whether OpenVDB uses std::shared_ptr or boost::shared_ptr.