[SOLVED] COLLADA Unit Support

[ulf.schroeter]

Problem

 

Current implementation of MeshFileDAE does not support COLLADA unit tag. This is bad as cool and free Google SketchUp7/8 modelling software ALWAYS exports COLLADA format with "inch" unit, even when modelling metrics are set to e.g. "meter". Google SketchUp modelled unit cube with 1 [m] edge length will be scaled by factor 39,37 (1[inch] = 0.0254[m]) on import with UNIGINE ResourceEditor tool for mesh conversion

 

<COLLADA xmlns="http://www.collada.org/2005/11/COLLADASchema" version="1.4.1">
   <asset>
       <contributor>
           <authoring_tool>Google SketchUp 8.0.4811</authoring_tool>
       </contributor>
       <unit meter="0.02539999969303608" name="inch" />
       <up_axis>Z_UP</up_axis>
   </asset>
...  

 

Proposal

 

Following lines of code in MeshFile.cpp will add generic COLLADA unit support

 

class MeshFileDAE : public MeshFile {
...
    int     up_axis;
1    float   unit_scale; // meter unit conversion scale 
...
};

void MeshFileDAE::parse_asset(const Xml *xml) {

   for(int i = 0; i < xml->getNumChilds(); i++) {
...
if(name == "up_axis") {
...
}
2       else if(name == "unit") {
3           unit_scale = x->getFloatArg("meter");
4           if( unit_scale == 0.0f )
5               unit_scale =  1.0f; // reset to default in case of parsing error
6       }
   }
}

void MeshFileDAE::parse_node(const Xml *xml,const mat4 &t) {

...
   if(name == "matrix") {
mat4 m;
x->getFloatArrayData(m,16);
7       m.m30 *= unit_scale; m.m31 *= unit_scale; m.m32 *= unit_scale;
transform = transform * transpose(m);
   }
...
   else if(name == "translate") {
vec3 t;
x->getFloatArrayData(t,3);
8       t *= unit_scale;
       transform = transform * translate(t.x,t.y,t.z);
   }
...
}

void MeshFileDAE::parse_primitive(const Xml *xml,Surface &surface) {
...
for(int i = 0; i < xml->getNumChilds(); i++) {
...
         // vertices
  for(int j = 0; j < indices.size(); j += stride) {
      Mesh::Vertex v;
             ...
             ...                
9             v.xyz *= unit_scale; // convert to COLLADA default unit meter

      vertex.append(v);
   }
          ....		
}
}

UnitCube.dae.txt

[serega]

Thanks, assigned to devs.

[frustum]

Feature is added.