Rendering bugs with Radeon HD 3650 (RV635) on Linux with Mesa

[illwieckz]

Given we recommend OpenGL 3.2 GPU (and the game may work with OpenGL 2.1) I may attempt to plug some older GPU to my computer to drive some tests.

I just did it with a Radeon HD 3650 (RV635) on Linux with Mesa 20.0.8 and glxinfo tells me OpenGL 3.3 is supported.

Don't expect a stellar experience (expect a 30~40 fps range) but it works, and except a warning telling me SSAO is not used because GL_ARB_texture_gather is not available, all features seems to work as far as I've seen (even relief mapping works, but you have to disable it because of performance).

The bug is that some far surfaces that are hidden by close geometry are rendered atop the close geometry hiding them. I can get that bug in plat23 or yocto maps for example. On chasm map when being outside the skybox is rendered above everything.

It may also be a driver bug, I don't know.

When outside is not rendered:

When outside is rendered (walked a bit to the left):

I'm close to a wall entirely hiding my viewport but I still see through:

The plat23 map really makes this bug very obvious:

You can also get the bug in yocto:

A bug affects the skybox in chasm, may be another bug or the same, I don't know: