How make visible the back face of a Mesh

Questions & Answers
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1

Hi,
i want to make the back face of a mesh visible. How can i make this?

Thnx

4

As @Eric5h5 said, removing backface culling works, but produces wrong lighting. You can double face the mesh by duplicating the triangles (the new ones must have inverted winding order) and the normals/vertices/uvs (you need reversed normals for the new triangles, what implies in duplicated vertices and uvs). Attach the script below to some object, and its mesh will become double faced:

function Start () {
    var mesh = GetComponent(MeshFilter).mesh;
	var vertices = mesh.vertices;
	var uv = mesh.uv;
	var normals = mesh.normals;
	var szV = vertices.length;
	var newVerts = new Vector3[szV*2];
	var newUv = new Vector2[szV*2];
	var newNorms = new Vector3[szV*2];
	for (var j=0; j< szV; j++){
		// duplicate vertices and uvs:
		newVerts[j] = newVerts[j+szV] = vertices[j];
		newUv[j] = newUv[j+szV] = uv[j];
		// copy the original normals...
		newNorms[j] = normals[j];
		// and revert the new ones
		newNorms[j+szV] = -normals[j];
	}
	var triangles = mesh.triangles;
	var szT = triangles.length;
	var newTris = new int[szT*2]; // double the triangles
	for (var i=0; i< szT; i+=3){
		// copy the original triangle
		newTris _= triangles*;*_
_*		newTris[i+1] = triangles[i+1];*_
_*		newTris[i+2] = triangles[i+2];*_
_*		// save the new reversed triangle*_
_*		j = i+szT;*_ 
_		newTris[j] = triangles*+szV;*_
_*		newTris[j+2] = triangles[i+1]+szV;*_
_*		newTris[j+1] = triangles[i+2]+szV;*_
_*	}*_
_*	mesh.vertices = newVerts;*_
_*	mesh.uv = newUv;*_
_*	mesh.normals = newNorms;*_
 _*mesh.triangles = newTris; // assign triangles last!*_
_*}*_
_*
*_
5

C# version of @aldonaletto’s script:

private void Start () {
	var mesh = GetComponent<MeshFilter>().mesh;
	var vertices = mesh.vertices;
	var uv = mesh.uv;
	var normals = mesh.normals;
	var szV = vertices.Length;
	var newVerts = new Vector3[szV*2];
	var newUv = new Vector2[szV*2];
	var newNorms = new Vector3[szV*2];
	for (var j=0; j< szV; j++){
		// duplicate vertices and uvs:
		newVerts[j] = newVerts[j+szV] = vertices[j];
		newUv[j] = newUv[j+szV] = uv[j];
		// copy the original normals...
		newNorms[j] = normals[j];
		// and revert the new ones
		newNorms[j+szV] = -normals[j];
	}
	var triangles = mesh.triangles;
	var szT = triangles.Length;
	var newTris = new int[szT*2]; // double the triangles
	for (var i=0; i< szT; i+=3){
		// copy the original triangle
		newTris _= triangles*;*_

* newTris[i+1] = triangles[i+1];*
* newTris[i+2] = triangles[i+2];*
* // save the new reversed triangle*
* var j = i+szT;*
_ newTris[j] = triangles*+szV;
 newTris[j+2] = triangles[i+1]+szV;
 newTris[j+1] = triangles[i+2]+szV;
 }
 mesh.vertices = newVerts;
 mesh.uv = newUv;
 mesh.normals = newNorms;
 mesh.triangles = newTris; // assign triangles last!
}*_

3

That’s how it works with backface culling. You can either turn off backface culling in the shader (but the lighting on the backface will be wrong), or create the mesh as double-sided.

2

Hi well the problem with this is that, it depends were you got the mesh and if you got it from the asset store or anywhere else in a unity run program, then click on the mesh in the project view and in the inspector make sure everything you want is selected, but if you got it from a 3d website like TurboSquid or if you imported it from a 3d modeling program, then most likely its the 3d modeling softwares settings, before you export a 3d model from somewhere make sure you check the export settings. And make sure everything you want to export is going to export.