Vertices in LoadObj is incorrect when TINYOBJLOADER_USE_DOUBLE is on

[jasjuang]

Given below minimal obj file

test.obj

v -126.4800033569 12.4945001602 -173.8119964600
v -126.6900024414 21.4505004883 -170.0980072021
v -108.1169967651 -28.3661003113 -170.7310028076
f 1 2 3

Please see below minimal code

void ReadOBJ(const std::string &obj_file,
             std::vector<double> &vert_pos,
             std::vector<int> &tri_ind){
  tinyobj::attrib_t attrib;
  std::vector<tinyobj::shape_t> shapes;
  std::vector<tinyobj::material_t> materials;
  std::string warn;
  std::string err;

  tinyobj::LoadObj(&attrib, &shapes, &materials, &warn, &err, obj_file.c_str());

  for (double vertice : attrib.vertices){
    vert_pos.emplace_back(vertice);

    std::cout << vertice << std::endl;
  }

  for (auto &shape : shapes){
    for (auto &indice : shape.mesh.indices){
      tri_ind.emplace_back(indice.vertex_index);
    }
  }
}

int main(){
  std::vector<double> vert_pos;
  std::vector<int> tri_ind;

  ReadOBJ("test.obj", vert_pos, tri_ind);

  std::cout << "total verts: " << vert_pos.size() << std::endl;
  return 0;
}

If TINYOBJLOADER_USE_DOUBLE is set to on in CMake while compiling tinyobjloader, the output is all wrong as shown below:

3.68883e+19
-3.49406
1.08357e-19
2.64045
-3.68995e+19
-3.58948
-nan
-3.49488
7.39465e-42
2.83516
-3.68897e+19
-3.58222
-3.68878e+19
-3.42233
-2.00139
-2.94322
3.68922e+19
-3.58346
total verts: 18

whereas if TINYOBJLOADER_USE_DOUBLE is set to off in CMake while compiling tinyobjloader, the output is as expected like below:

-126.48
12.4945
-173.812
-126.69
21.4505
-170.098
-108.117
-28.3661
-170.731
total verts: 9

@syoyo @noma please take a look, many thanks.

[syoyo]

At least compiling loader_example.cc with -DTINYOBJLOADER_USE_DOUBLE=1 works fine.

Have you defined TINYOBJLOADER_USE_DOUBLE for each tiny_obj_loader.h inclusion?

#define TINYOBJLOADER_USE_DOUBLE
#include "tiny_obj_loader.h"

[jasjuang]

Thanks for the pointer. Adding target_compile_definitions(${PROJECT_NAME} PUBLIC TINYOBJLOADER_USE_DOUBLE) in the downstream CMakeLists actually does solve it for me, but why is this required when the CMake option TINYOBJLOADER_USE_DOUBLE is already set to on in the upstream?

[syoyo]

https://github.com/syoyo/tinyobjloader/blob/master/tiny_obj_loader.h#L130

real_t is ifdef'ed at header level, so you need to define TINYOBJLOADER_USE_DOUBLE for each tiny_obj_loader.h inclusion.

Using templated type for real_t will solve such a confusion #233

[jasjuang]

Thanks. Looking forward to a solution to #233.

[syoyo]

Looking forward to a solution to #233.

You can contribute to support better double-precision support(and also quadruple-precision floating point if required)

[noma]

Taking another look on the CMakeFiles.txtit would probably more modern CMake to replace the global:

add_definitions(-DTINYOBJLOADER_USE_DOUBLE)

By something like this, after the add_library():

if(TINYOBJLOADER_USE_DOUBLE)
    target_compile_definitions(${LIBRARY_NAME} PUBLIC TINYOBJLOADER_USE_DOUBLE)
endif()

Other targets within the project as well in external CMake projects using the ${LIBRARY_NAME} target as a dependency should get the define automatically this way.

[jasjuang]

@noma thanks for the suggestion, it works, please see PR #238.