Create mesh like plane (side not visible)

[benjydel]

Hi !

I have to create a room in babylon js. I have used 4 plane for the walls and a ground for the ground. With that, we can see all the time on the room because some side are visible and some not.

I would like to know if we can do that with some other mesh like ligne. I have to do a grid on the wall and the ground.

 

Tkanks !

[jerome]

to design a grid made with several lines, the LineSystem would be the right candidate : http://doc.babylonjs.com/tutorials/Mesh_CreateXXX_Methods_With_Options_Parameter#linesystem

[benjydel]

29 minutes ago, jerome said:

to design a grid made with several lines, the LineSystem would be the right candidate : http://doc.babylonjs.com/tutorials/Mesh_CreateXXX_Methods_With_Options_Parameter#linesystem

Ho thank you but i can't find the documentation about this thing 

[adam]

If you need one side of the LineSystem to be invisible, you can do something like this:

http://www.babylonjs-playground.com/#1DKDYG#3

The sideOrientation property doesn't work for LineSystem or LinesMesh.

[benjydel]

12 hours ago, adam said:

If you need one side of the LineSystem to be invisible, you can do something like this:

http://www.babylonjs-playground.com/#1DKDYG#3

The sideOrientation property doesn't work for LineSystem or LinesMesh.

Thank you very much 

I try to understand how your solution works but i am blocked at this lines :
 

var mat = camera.getWorldMatrix();
		
		camVec.x = mat.m[8];
		camVec.y = mat.m[9];
		camVec.z = mat.m[10];

How do you know which coordonate is the "camVec" ?
Because i need to repeat this on other planes

An other question : 
Can i add several  registerBeforeRender() ?? I mean, if y iterate this again won't it be erase ??

Thank you very much again

[adam]

It appears as though you can add several registerBeforeRender functions.

http://www.babylonjs-playground.com/#1DKDYG#4

1 hour ago, benjydel said:

How do you know which coordonate is the "camVec" ?
Because i need to repeat this on other planes

You can do this instead:

http://www.babylonjs-playground.com/#1DKDYG#6

If the dot product of the camera direction vector and the normal of the plane is negative, then the plane should be facing you.

I'm not sure why it isn't working perfectly though if the plane is translated like this:

http://www.babylonjs-playground.com/#1DKDYG#5

Maybe someone else here will know what the issue is.

 

[benjydel]

Thank you @adam I finally found the issue.

But i can't explain how it work, I have been inspired of your solution:

    var VecteurNormal;
    var camVec = BABYLON.Vector3.Zero();
    
            VecteurNormal = BABYLON.Vector3.Cross(new BABYLON.Vector3(0,-1,0), new BABYLON.Vector3(0,0,-1));
           
    scene.registerBeforeRender(function () {
        var mat = camera.getWorldMatrix();
        camVec.x = mat.m[12];
        camVec.y = mat.m[13];
        camVec.z = mat.m[14];
        var dot = BABYLON.Vector3.Dot(camVec, VecteurNormal);
        if (dot > 0) {
            ligne.visibility = 1;
        } else {
            ligne.visibility = 0;
        }
    });

And if there is a translation :

camVec.x = mat.m[12]+xTranslation;
camVec.y = mat.m[13]+yTranslation;
camVec.z = mat.m[14]+zTranslation;

 

[adam]

19 hours ago, benjydel said:

And if there is a translation :

camVec.x = mat.m[12]+xTranslation;
camVec.y = mat.m[13]+yTranslation;
camVec.z = mat.m[14]+zTranslation;

You are going to need the dot product of normalized vectors.

[adam]

I think I figured out what I was doing wrong:

http://www.babylonjs-playground.com/#1DKDYG#7

https://en.wikipedia.org/wiki/Back-face_culling#Implementation