Z-axis pointing up

[minexew]

Hello,

I've started porting my PlayCanvas-based project to BABYLON.js, but I seem to be stuck on a fairly basic thing - I cannot figure how to convince the engine that in my scene, the up axis is not Y, but Z.

Basically I'm looking for the BABYLON equivalent of the following code:

var camera = new pc.Entity();
g_camera = camera.addComponent("camera", {
    clearColor: new pc.Color(zoneData.bgColor[0], zoneData.bgColor[1], zoneData.bgColor[2])
});
app.root.addChild(camera);

var cameraDist = 10;

// look at [0 0 0] from [-1 -1 1]*cameraDist to get a Diablo-style view
// [0 0 1] points up
var camVec = new pc.Vec3(-1, -1, 1);
camVec.scale(cameraDist / camVec.length());

var camLookAt = pc.Vec3.ZERO;
var camUp = new pc.Vec3(1, 1, 1);
camUp.normalize();

camera.setPosition(camVec);
camera.lookAt(camLookAt, camUp);

// later on - translate camera to follow the player
camera.setPosition(camVec.clone().add(self.playerEntity.getPosition()));

 

I wouldn't mind using ArcRotateCamera if I can get it to work.

I tried setting camera.upVector, but that just ended up distorting the view.

Then I tried the following dirty hack, but that didn't do the job either (no errors, but nothing is displayed)

(<any>camera)._camMatrix = BABYLON.Matrix.Zero();
BABYLON.Matrix.LookAtLHToRef(camVec, camLookAt, camUp, (<any> camera)._camMatrix);

Thanks for any help.

[GameMonetize]

Hello and welcome,

can you provide a sample repro case on the playground. Setting up camera.upVector should work

[minexew]

Indeed, seems to work in the playground (except for mouse control, but that's not important for me).

I'll re-check my code.

[GameMonetize]

I love when a plan comes together

[minexew]

Part of what I had done wrong was setting upVector to the "correct" [1 1 1].normalize() instead of simply [0 0 1].

However, as you can see in the playground I linked, the view is still not quite correct - it's shifted the right and looks slightly tilted. What would be the right way to fix that?

[GameMonetize]

I know. THe best option by far would be to keep upAxis unchanged and just rotate your models after loading them.

 

Babylonjs is left handed, Y up.

[minexew]

Well crap, thought I wasn't asking that much.

Chaging to Y-up would mean not only rotating all the models, but also their placement, and also all logic dealing with entities' position, rotation and so on. The codebase is not that small.

Is it possible to transform the entire world except the camera? That would do without changing everything.

[Sebavan]

Maybe you could place all your Mesh under one node used only for its transform moving from Y to Z up ?

I guess your pivot Matrix could look like this:

1 0 0 0

0 0 1 0

0 1 0 0

0 0 0 1

 

[minexew]

That was the first thing I tried to do. Lights seem to ignore the transformation though - see http://www.babylonjs-playground.com/#QQJSV#1

 

What options do I have left? Would implementing my own Camera work?

[Sebavan]

Seems to work with directional light :-)

http://www.babylonjs-playground.com/#QQJSV#2

well lit on z up. Hemispheric Light define their direction in world space directly. so basically, as long as you correct hemispheric light maunallly (and probably a few other bits) it should be ok. 

 

[minexew]

I ended up copying ArcRotateCamera, throwing most of the guts away and fixing what I needed. Seems to work good enough so far.

[dbawel]

@minexew,

Could it be that you exported from a Z axis up application? Perhaps take a look at the last post I wrote on the link below - bottom of the page:

DB

[GameMonetize]

@minexew: I'm interested by what you changed in the ArcRotateCamera. Perhaps we can integrate your changes?

[minexew]

On 4/11/2016 at 7:56 AM, dbawel said:

@minexew,

Could it be that you exported from a Z axis up application?

All our assets, as well as the server software, are built as Z-up. I intend to keep it that way, not just because the work involved in changing everything, but because Z-up is really the only system that makes sense to me in any non-trivial 3D world.

 

On 4/11/2016 at 11:20 PM, Deltakosh said:

@minexew: I'm interested by what you changed in the ArcRotateCamera. Perhaps we can integrate your changes?

I did it in a rather hacky way, implementing only the absolute minimum needed. However, if you're interesting in merging this, I can look into developing a proper patch.

 

Thanks for all the help.

[GameMonetize]

No worry, I understand  I'm happy as long as it works for you,