[Intel][OpenGL] glDepthFunc(GL_EQUAL) doesn't work correctly on Intel Linux Mesa OpenGL drivers
It seems glDepthFunc(GL_EQUAL) doesn't work correctly on Intel Linux Mesa OpenGL drivers.
Steps to reproduce:
- Download and unzip OpenGL_test_write_depth.zip
- Run ./test or build it from "test.c" with "gcc -o test test.c -lX11 -lepoxy"
On Ubuntu 20.04 (Mesa version 20.0.8) using Intel UHD630 GPU, the output is wrong:
GLError after glReadPixels: 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
GLError after glMapBufferRange: 0
While on AMD, NVidia, and Windows Intel OpenGL driver (also UHD630), we can get the correct output:
GLError after glReadPixels: 0
1 1 1 1
1 1 1 1
1 1 1 1
1 1 1 1
GLError after glMapBufferRange: 0