[SOLVED!] Polygon render order problem

bgsteffens · Post by **bgsteffens** » Fri Dec 08, 2006 6:14 am

Hello all

I made a basic mesh of a house in Maya, exported to OBJ format, and loaded into Irrlicht with the following code:

IAnimatedMesh* meshHouse = smgr->getMesh("house.obj");
IAnimatedMeshSceneNode* house = smgr->addAnimatedMeshSceneNode(meshHouse);
if(house)
{
	house->setMaterialFlag(EMF_LIGHTING, false);
}

As you can see below, the house seems to display correctly..

But when viewed from the side or below..

Download the evil mesh here

Any insight into the cause of this problem would be greatly appreciated. Thanks!

JP · Post by JP » Fri Dec 08, 2006 12:19 pm

Turn the back face culling off, i think it's setMaterialFlag(EMF_BACK_FACE_CULLING, false);

bgsteffens · Post by **bgsteffens** » Fri Dec 08, 2006 5:52 pm

That just makes everything turn inside-out. O_O

With back-face culling set to false:

JP · Post by JP » Fri Dec 08, 2006 6:26 pm

Ok, now just after you load the mesh, but before you create a node with it, use the meshManipulator from the smgr to flip the surfaces of your model and that might fix it.

hybrid · Post by **hybrid** » Fri Dec 08, 2006 9:03 pm

Better fix the model in your 3d editor.

bgsteffens · Post by **bgsteffens** » Sat Dec 09, 2006 1:29 am

Thanks for the replies, guys.

JP: After flipping the surfaces:

hybrid: I did assume this was a problem with the model itself, not the code used to load it. Any insight into what the problem with the model could be? I know next-to-nothing about modelling and am only trying to understand it as it applies to game programming so that I can make basic testing meshes.

Thanks both of you

zeno60 · Post by **zeno60** » Sat Dec 09, 2006 3:09 am

I know nothing about modeling myself, but is it looking like no matter where you view your model from it is "inside-out"? If this is the case, then see if you have an option in your modeling program about "flipping normals." In 3DS Max you can do this by applying a normal modifier and check/uncheck "flip normals." I'm assuming it would be done a similar way in any other modeling program. Hope this helps.

bgsteffens · Post by **bgsteffens** » Sat Dec 09, 2006 3:25 am

After flipping normals:

bitplane · Post by **bitplane** » Sat Dec 09, 2006 10:42 pm

as i was about to say on irc, it could be a transparency problem. try setting a solid material with setMaterial

bgsteffens · Post by **bgsteffens** » Sat Dec 09, 2006 11:13 pm

Code: Select all

house->setMaterialType(EMT_SOLID);

FIXED!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

bitplane, I love you =P

bitplane · Post by **bitplane** » Sun Dec 10, 2006 2:06 am

for future reference, the wrong material was set due to a bug in the MTL loader- if your .MTL file includes the line-

Code: Select all

Tf 1.0,1.0,1.0

then EMT_TRANSPARENT_VERTEX_ALPHA was set, this is now fixed in the latest revision.
if you're exporting non-transparent objects from Maya, either delete the line out of your MTL file, or use svn revision 335 or later