(C++) Add your own cube node

[rogerborg]

I was asked about how to get the mesh from a cube node created by ISceneManager::addCubeSceneNode(), and as far as I can see, you can't, because it creates an internal class, CCubeSceneNode, which has no interface that exposes its mesh.

So, short of modifying the engine (to make CCubeSceneNode an IMeshSceneNode and return an IMeshSceneNode from addCubeSceneNode()), I'd do it with something like this:

Code: Select all

	f32 cubeSize = 5.f;
	video::SColor cubeColour(255,255,255,255);

	SMeshBuffer * buffer = new SMeshBuffer();
	u16 u[36] = {   0,2,1,   0,3,2,   1,5,4,   1,2,5,   4,6,7,   4,5,6, 
            7,3,0,   7,6,3,   9,5,2,   9,8,5,   0,11,10,   0,10,7};

	buffer->Indices.set_used(36);
	for (s32 i=0; i<36; ++i)
		buffer->Indices[i] = u[i];

	buffer->Vertices.set_used(12);
	buffer->Vertices[0]  = video::S3DVertex(0,0,0, -1,-1,-1, cubeColour, 0, 1); 
	buffer->Vertices[1]  = video::S3DVertex(1,0,0,  1,-1,-1, cubeColour, 1, 1); 
	buffer->Vertices[2]  = video::S3DVertex(1,1,0,  1, 1,-1, cubeColour, 1, 0); 
	buffer->Vertices[3]  = video::S3DVertex(0,1,0, -1, 1,-1, cubeColour, 0, 0); 
	buffer->Vertices[4]  = video::S3DVertex(1,0,1,  1,-1, 1, cubeColour, 0, 1); 
	buffer->Vertices[5]  = video::S3DVertex(1,1,1,  1, 1, 1, cubeColour, 0, 0); 
	buffer->Vertices[6]  = video::S3DVertex(0,1,1, -1, 1, 1, cubeColour, 1, 0); 
	buffer->Vertices[7]  = video::S3DVertex(0,0,1, -1,-1, 1, cubeColour, 1, 1); 
	buffer->Vertices[8]  = video::S3DVertex(0,1,1, -1, 1, 1, cubeColour, 0, 1); 
	buffer->Vertices[9]  = video::S3DVertex(0,1,0, -1, 1,-1, cubeColour, 1, 1); 
	buffer->Vertices[10] = video::S3DVertex(1,0,1,  1,-1, 1, cubeColour, 1, 0); 
	buffer->Vertices[11] = video::S3DVertex(1,0,0,  1,-1,-1, cubeColour, 0, 0); 

	buffer->BoundingBox.reset(0,0,0); 

	for (int i=0; i<12; ++i)
	{
		buffer->Vertices[i].Pos -= core::vector3df(0.5f, 0.5f, 0.5f);
		buffer->Vertices[i].Pos *= cubeSize;
		buffer->BoundingBox.addInternalPoint(buffer->Vertices[i].Pos);
	}

	SMesh * cubeMesh = new SMesh();
	cubeMesh->addMeshBuffer(buffer);

	ISceneNode * cubeSceneNode = smgr->addMeshSceneNode(cubeMesh);

... then set up cubeSceneNode with any properties that you need.

[de3000]

Thanx rogerborg I was just about to post a question about this.

and yes i do know this thread is old but is nice to say thanx

[rogerborg]

And it's nice to be thanked.

Is this the part where we kiss?

[hybrid]

Yeah, go for it and show some video of it

[rogerborg]

No way, that's a DMCA takedown waiting to happen.

[sio2]

Note that if you want to texture each face you'll need 24 vertices - fewer depending on how many corners can share texcoords.

[de3000]

And it's nice to be thanked.

Is this the part where we kiss?

Kiss? ummm NO! lol

ANYWAY....

im using Jirr wrapper and well mesh buffers aren't friendly just yet. lol

[Helderash]

Would there be any way to loop around the section setting vertices, e.g.

buffer->Vertices[0] = video::S3DVertex(0,0,0, -1,-1,-1, cubeColour, 0, 1);

to automatically generate cubes from a larger number of vertices? I'm working on some deformation experiments, and need to form a large cube from a number of smaller elements (smaller cubes). I'm just terrified of having to assign them one after another, especially when I plan to be using over 1000 vertices in some cases.

Thanks!

[hybrid]

Best thing would be to check the CSphereSceneNode and copy over the node handling to CubeSceneNode. It should allow to define the vertical and horizontal vertices, defaulting to 1 for backward compatibility. Then upload the new class and we will add it to Irrlicht

[BlindSide]

So if I wanted to look at this cube from the inside, eg, skybox, all I would need to do is invert the Indice direction vector numbers? (eg -1,-1,-1 to 1,1,1)

[vitek]

No, that would just change the normal that is used for lighting calculations. Actually the normals that are provided in this code are invalid as they should be normalized.

Anyways, you would need to reorder the indices in the index buffer if you wanted to see the box from the inside. Either that or disable backface culling on the material for the box.

Travis

[BlindSide]

Yeah I just times them by a negative number and it was sweet.
(The vertex positions)

Cheers

[Cyberdrill]

Please, tell how Vertices for Mesh Buffer were defined!? I try, but can't find any regularities... And how defined their normales?... And why there are 12 vertices? (cube has only 8 geometric vertices...) I'm really panic now )))