what are the common differences that i should know about? also specifically ive heard that opengl and directx has different light ray direction? which one is which
Buffer direction is probably what they meant. OpenGL by default starts from the bottom left whereas DirectX starts from the top left. Meaning pixel 0,0 in DX is top left, pixel 0,0 in OpenGL is bottom left. However, this can be changed in code so it's not always an issue, Substance Designer/Painter use DirectX vs OpenGL normal naming conventions for historic reasons more than anything.
Other differences include matrix operation orders, handedness (though since DX9/10 I believe they're the same handedness by default) and shader compilers. The shader compilers is a pretty big one, it means that HLSL compilers may or may not have some features that GLSL compilers have and vice versa.
Worth mentioning that DX12 is a bit more like Vulkan than OpenGL. Also Just because Vulkan is more "powerful" (driver level), doesn't mean that OpenGL is going anywhere, at least for now.
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Buffer direction is probably what they meant. OpenGL by default starts from the bottom left whereas DirectX starts from the top left. Meaning pixel 0,0 in DX is top left, pixel 0,0 in OpenGL is bottom left. However, this can be changed in code so it's not always an issue, Substance Designer/Painter use DirectX vs OpenGL normal naming conventions for historic reasons more than anything.
Other differences include matrix operation orders, handedness (though since DX9/10 I believe they're the same handedness by default) and shader compilers. The shader compilers is a pretty big one, it means that HLSL compilers may or may not have some features that GLSL compilers have and vice versa.
Worth mentioning that DX12 is a bit more like Vulkan than OpenGL. Also Just because Vulkan is more "powerful" (driver level), doesn't mean that OpenGL is going anywhere, at least for now.
For an artist: None of this matters.
also found this one after 2 minutes:
https://www.turbosquid.com/3d-modeling/stemcell/materials-texturing-stemcell/stemcell-texturing-guide/