I was researching some real example application Greedy Mesh WITH TEXTURES working in jME and found a GitHub project. But unfortunately, when I turn textures they were white, asked the author of the topic and he told me it’s because I do not have modern OpenGL, but making a game without support older PC is not an option for me, so I wanted some help as to make this code work on old OpenGL.
Github project + Screenshots here: Textures not working · Issue #3 · Sleaker/Cubed · GitHub
This project uses texture arrays to support a large number of textures. Texture arrays require OpenGL 3.0 or higher.
You will need to use a different shader if you want to support older platforms.
“You will need to use a different shader if you want to support older platforms.”
The problem is that I am jME beginner, and I have no idea how to do this.
That library was not designed to run on older devices, basically. You can try asking the author to make a version which does not use texture arrays.
Cube worlds / Minecraft clones are probably not a good start for a beginner, as they are fairly complex.