Flipped axis on imported Sketchup OBJ

[erixon]

Hello!

One axis is flipped when I imported an object from Sketchup/OBJ into Babylonjs. What is the easiest solution to solve this?

kind regards
Tomas

[GameMonetize]

hey!

If only one axis is inverted you can edit the mesh data (mesh.getVerticesData) and invert Y value. But I'm afraid this could be more a right handed vs. left handed question. In this case you should export your model with the right axis (check "Good things to know here:https://github.com/BabylonJS/Babylon.js/tree/master/loaders/OBJ)

[erixon]

Sketchup export options are few. One little bit odd solution is to flip in sketchup/work mirrored. Another is to make a script for the obj-file. I guess if I edit the data and like update normals also, it sounds unnecessary heavy clientside.

Thanks anyways, unfortunately this kind of development with many softwares seldom is 'it just works'. But I'm happy that I can import, some year ago I had trouble with the converter not working.

kind regards
Tomas

[GameMonetize]

An option could be to use Blender to import the obj and then export .babylon from blender

[Kesshi]

Here a typescript function i wrote some time ago to convert a geometry to left handed. I also used it in combination with th OBJ loader.
 

public static geometryToLeftHanded(pGeom: BABYLON.Geometry): void
{
	if (pGeom == null)
		return;

	//flip faces
	let tIndices = pGeom.getIndices(false);
	if (tIndices != null && tIndices.length > 0) {
		for (let i = 0; i < tIndices.length; i += 3) {
			let tTemp = tIndices[i + 0];
			tIndices[i + 0] = tIndices[i + 2];
			tIndices[i + 2] = tTemp;
		}
		pGeom.setIndices(tIndices);
	}

	//negate position.z
	let tPositions = pGeom.getVerticesData(BABYLON.VertexBuffer.PositionKind, false);
	if (tPositions != null && tPositions.length > 0) {
		for (let i = 0; i < tPositions.length; i += 3) {
			tPositions[i + 2] = -tPositions[i + 2];
		}
		pGeom.setVerticesData(BABYLON.VertexBuffer.PositionKind, tPositions, false);
	}

	//negate normal.z
	let tNormals = pGeom.getVerticesData(BABYLON.VertexBuffer.NormalKind, false);
	if (tNormals != null && tNormals.length > 0) {
		for (let i = 0; i < tNormals.length; i += 3) {
			tNormals[i + 2] = -tNormals[i + 2];
		}
		pGeom.setVerticesData(BABYLON.VertexBuffer.NormalKind, tNormals, false);
	}
}

 

[GameMonetize]

Hey Kesshi! this is worth a PR to me

[Kesshi]

7 hours ago, Deltakosh said:

Hey Kesshi! this is worth a PR to me

I will put it on my todo list ... a bit busy at the moment

[GameMonetize]

I can do it for you if you want

[Kesshi]

Yes you can do it if you have the time. Lot of things to do at work at the moment and at home my 1 year old daughter keeps me busy
I'm also not so sure if it should be a Tools function or directly a function of the Geometry class.

[GameMonetize]

Done

[Kesshi]

nice, one more function i can remove from my code base :-)

[erixon]

Thanks for the replies. I initially choosed obj because it looked like a nice compact format supported by Sketchup.

Though struggling hours in Blender with small errors in my baked textures and the flipped problem, I started to use the babylon-format and it solved more or less all my problems.

I really hate blender ui but it helps me with the baking. But Babylonjs is wonderful :-)

kind regards
Tomas

[GameMonetize]

Lol thanks!