OBJ File for ARCore Application Development

Question

What is the significance of the andy.obj file in the ARCore Sample?

Let's say if we replace the andy.png with a new image, how can we generate .obj file for the new image?

Answer 1

The OBJ file describes the geometry, the png file the texture to "stretch" over this 3D object. You have to use a 3D modelling program like Blender to create a new model.

This is how you export OBJ files in Blender: https://blender.stackexchange.com/questions/121/how-do-i-export-a-model-to-obj-format

Answer 2

The sample code only can handle the simplest OBJ models that only have 1 texture file.

Fo those complicated OBJ models, they usually come with a MTL file that refers to several different texture files. To be able to handle that ,you need some extra work on the existing code. Please check the code I implement for this case if you are interested @https://github.com/JohnLXiang/arcore-sandbox . Specifially ,you can take a look at ObjectRenderer.createOnGlThread().