c++nvidiameshassimpoptix
Ray Tracing using Nvidia Optix with Open Asset Import Library (assimp) - rendering multiple meshes
I'm trying to combine the versatility of Open Asset Import Library (reading in a variety of 3D model filetypes) with NVidia Optix ray tracing to render the models.
So far, it is working whenever the model I'm rendering is made up of a single mesh. When I try to render a file with more than one mesh, I get only partial results. I can't narrow down where the issue is, looking for some insight. Relevant code here:
Loading a file using assimp importer and creating the optix buffers:
int loadAsset(const char* path)
{
Assimp::Importer importer;
scene = importer.ReadFile(
path,
aiProcess_Triangulate
//| aiProcess_JoinIdenticalVertices
| aiProcess_SortByPType
| aiProcess_ValidateDataStructure
| aiProcess_SplitLargeMeshes
| aiProcess_FixInfacingNormals
);
if (scene) {
getBoundingBox(&scene_min, &scene_max);
scene_center.x = (scene_min.x + scene_max.x) / 2.0f;
scene_center.y = (scene_min.y + scene_max.y) / 2.0f;
scene_center.z = (scene_min.z + scene_max.z) / 2.0f;
float3 optixMin = { scene_min.x, scene_min.y, scene_min.z };
float3 optixMax = { scene_max.x, scene_max.y, scene_max.z };
aabb.set(optixMin, optixMax);
unsigned int numVerts = 0;
unsigned int numFaces = 0;
if (scene->mNumMeshes > 0) {
printf("Number of meshes: %d\n", scene->mNumMeshes);
// get the running total number of vertices & faces for all meshes
for (unsigned int i = 0; i < scene->mNumMeshes; i++) {
numVerts += scene->mMeshes[i]->mNumVertices;
numFaces += scene->mMeshes[i]->mNumFaces;
}
printf("Found %d Vertices and %d Faces\n", numVerts, numFaces);
// set up buffers
optix::Buffer vertices = context->createBuffer(RT_BUFFER_INPUT, RT_FORMAT_FLOAT3, numVerts);
optix::Buffer normals = context->createBuffer(RT_BUFFER_INPUT, RT_FORMAT_FLOAT3, numVerts);
optix::Buffer faces = context->createBuffer(RT_BUFFER_INPUT, RT_FORMAT_UNSIGNED_INT3, numFaces);
optix::Buffer materials = context->createBuffer(RT_BUFFER_INPUT, RT_FORMAT_UNSIGNED_INT, numVerts);
// unused buffer
Buffer tbuffer = context->createBuffer(RT_BUFFER_INPUT, RT_FORMAT_FLOAT2, 0);
// create material
std::string defaultPtxPath = "C:\\ProgramData\\NVIDIA Corporation\\OptiX SDK 4.1.0\\SDK\\build\\lib\\ptx\\";
Program phong_ch = context->createProgramFromPTXFile(defaultPtxPath + "optixPrimitiveIndexOffsets_generated_phong.cu.ptx", "closest_hit_radiance");
Program phong_ah = context->createProgramFromPTXFile(defaultPtxPath + "optixPrimitiveIndexOffsets_generated_phong.cu.ptx", "any_hit_shadow");
Material matl = context->createMaterial();
matl->setClosestHitProgram(0, phong_ch);
matl->setAnyHitProgram(1, phong_ah);
matl["Kd"]->setFloat(0.7f, 0.7f, 0.7f);
matl["Ka"]->setFloat(1.0f, 1.0f, 1.0f);
matl["Kr"]->setFloat(0.0f, 0.0f, 0.0f);
matl["phong_exp"]->setFloat(1.0f);
std::string triangle_mesh_ptx_path(ptxPath("triangle_mesh.cu"));
Program meshIntersectProgram = context->createProgramFromPTXFile(triangle_mesh_ptx_path, "mesh_intersect");
Program meshBboxProgram = context->createProgramFromPTXFile(triangle_mesh_ptx_path, "mesh_bounds");
optix::float3 *vertexMap = reinterpret_cast<optix::float3*>(vertices->map());
optix::float3 *normalMap = reinterpret_cast<optix::float3*>(normals->map());
optix::uint3 *faceMap = reinterpret_cast<optix::uint3*>(faces->map());
unsigned int *materialsMap = static_cast<unsigned int*>(materials->map());
context["vertex_buffer"]->setBuffer(vertices);
context["normal_buffer"]->setBuffer(normals);
context["index_buffer"]->setBuffer(faces);
context["texcoord_buffer"]->setBuffer(tbuffer);
context["material_buffer"]->setBuffer(materials);
Group group = createSingleGeometryGroup(meshIntersectProgram, meshBboxProgram, vertexMap,
normalMap, faceMap, materialsMap, matl);
context["top_object"]->set(group);
context["top_shadower"]->set(group);
vertices->unmap();
normals->unmap();
faces->unmap();
materials->unmap();
}
return 0;
}
return 1;
}
And the relevant function for creating the geometries and filling the buffers:
Group createSingleGeometryGroup(Program meshIntersectProgram, Program meshBboxProgram, optix::float3 *vertexMap,
optix::float3 *normalMap, optix::uint3 *faceMap, unsigned int *materialsMap, Material matl) {
Group group = context->createGroup();
optix::Acceleration accel = context->createAcceleration("Trbvh");
group->setAcceleration(accel);
std::vector<GeometryInstance> gis;
unsigned int vertexOffset = 0u;
unsigned int faceOffset = 0u;
for (unsigned int m = 0; m < scene->mNumMeshes; m++) {
aiMesh *mesh = scene->mMeshes[m];
if (!mesh->HasPositions()) {
throw std::runtime_error("Mesh contains zero vertex positions");
}
if (!mesh->HasNormals()) {
throw std::runtime_error("Mesh contains zero vertex normals");
}
printf("Mesh #%d\n\tNumVertices: %d\n\tNumFaces: %d\n", m, mesh->mNumVertices, mesh->mNumFaces);
// add points
for (unsigned int i = 0u; i < mesh->mNumVertices; i++) {
aiVector3D pos = mesh->mVertices[i];
aiVector3D norm = mesh->mNormals[i];
vertexMap[i + vertexOffset] = optix::make_float3(pos.x, pos.y, pos.z) + aabb.center();
normalMap[i + vertexOffset] = optix::normalize(optix::make_float3(norm.x, norm.y, norm.z));
materialsMap[i + vertexOffset] = 0u;
}
// add faces
for (unsigned int i = 0u; i < mesh->mNumFaces; i++) {
aiFace face = mesh->mFaces[i];
// add triangles
if (face.mNumIndices == 3) {
faceMap[i + faceOffset] = optix::make_uint3(face.mIndices[0], face.mIndices[1], face.mIndices[2]);
}
else {
printf("face indices != 3\n");
faceMap[i + faceOffset] = optix::make_uint3(-1);
}
}
// create geometry
optix::Geometry geometry = context->createGeometry();
geometry->setPrimitiveCount(mesh->mNumFaces);
geometry->setIntersectionProgram(meshIntersectProgram);
geometry->setBoundingBoxProgram(meshBboxProgram);
geometry->setPrimitiveIndexOffset(faceOffset);
optix::GeometryInstance gi = context->createGeometryInstance(geometry, &matl, &matl + 1);
gis.push_back(gi);
vertexOffset += mesh->mNumVertices;
faceOffset += mesh->mNumFaces;
}
printf("VertexOffset: %d\nFaceOffset: %d\n", vertexOffset, faceOffset);
// add all geometry instances to a geometry group
GeometryGroup gg = context->createGeometryGroup();
gg->setChildCount(static_cast<unsigned int>(gis.size()));
for (unsigned i = 0u; i < gis.size(); i++) {
gg->setChild(i, gis[i]);
}
Acceleration a = context->createAcceleration("Trbvh");
gg->setAcceleration(a);
group->setChildCount(1);
group->setChild(0, gg);
return group;
}
Running the above code on a sample file from assimp (using the dwarf.x, file contains 2 meshes) yields this result:
You can see only part of the second mesh (the dwarf's body) is rendered. I tried rendering each mesh separately, one at a time, and they render in full. But when putting them together I get this.
I'm thinking the issue is either with creating the geometry, perhaps I have these lines wrong:
geometry->setPrimitiveCount(mesh->mNumFaces);
geometry->setPrimitiveIndexOffset(faceOffset);
or the assimp postprocessing flags
scene = importer.ReadFile(
path,
aiProcess_Triangulate
//| aiProcess_JoinIdenticalVertices
| aiProcess_SortByPType
| aiProcess_ValidateDataStructure
| aiProcess_SplitLargeMeshes
| aiProcess_FixInfacingNormals
);
(note above, I had to comment out JoinIdenticalVertices because it gave me a horribly wrong result shown below):
Has anyone been able to successfully combine nvidia optix with open asset import library for rendering files with multiple meshes?
Solution
I found a solution, although not sure how optimal.
Each mesh still gets its own geometry, however instead of creating single vertex, index and normal buffers which are shared among all geometries, I create separate buffers for each geometry.
Then, instead of
context["vertex_buffer"]->setBuffer(vertices);
context["normal_buffer"]->setBuffer(normals);
context["index_buffer"]->setBuffer(faces);
context["texcoord_buffer"]->setBuffer(tbuffer);
context["material_buffer"]->setBuffer(materials);
I use
geometry["vertex_buffer"]->setBuffer(vertices);
geometry["normal_buffer"]->setBuffer(normals);
geometry["index_buffer"]->setBuffer(faces);
geometry["texcoord_buffer"]->setBuffer(tbuffer);
geometry["material_buffer"]->setBuffer(materials);
The result:
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