merged in main

CMakeLists.txt

shaders/basic.vert

shaders/ground.frag

shaders/surface.frag

shaders/surface.vert

src/hdr.h

src/main.cpp

src/surface.cpp

src/surface.h

textures/autumn_field_puresky_4k.hdr

textures/dirt.tga

textures/grass.tga