Normal Mapping Adventures // OpenGL Intermediate Series

[@OGLDEV]

Clone the sources:
git clone --recurse-submodules github.com/emeiri/ogldev.git
If you want to get the same version that was used in the video you can checkout the tag 'TUT_52_NORMAL_MAPPING'.
Build on Windows:
Open the Visual Studio solution: ogldev\Windows\ogldev_vs_2022\ogldev_vs_2022.sln
Build the project 'OpenGL\Tutorials\Tutorial52_NormalMapping'

[@CodeParticles]

@OGLDEV, just for fun Joey de Vries has a hasty function in GLSL's Fragment shader that calculates tangent normals to world space instead of bringing over tangent and bitangent attributes to the Vertex shader by using derivatives. I tried comparing both methods but I couldn't visually tell which was better; Perhaps just a smidge but he did mention this technique was more overhead than the former:
vec3 Get_TBN()
{
vec3 Tangent_Normal = texture(Normal_Map, Texture_Coordinates).xyz * 2.f - 1.f;
vec3 WderivX = dFdx(World_Position);
vec3 WderivY = dFdy(World_Position);
vec2 TderivX = dFdx(Texture_Coordinates);
vec2 TderivY = dFdy(Texture_Coordinates);
vec3 T = normalize(WderivX * TderivY.t - WderivY * TderivX.t);
vec3 N = normalize(Normal);
vec3 B = -normalize(cross(N, T));
mat3 TBN = mat3(T, B, N);
return normalize(TBN * Tangent_Normal);
}

[@OGLDEV]

Thanks. This is quite advanced. I still haven't used the derivatives in my tutorials.

[@tanveerasif5978]

Thank you so much.

[@OGLDEV]

You're welcome :-)

[@alfonsomaparicio6130]

Amazing explanation !!

[@OGLDEV]

Thank you!

[@frag-z3354]

Great explanations!

[@OGLDEV]

Thanks!

[@radueduard587]

Great video! I implemented this technique in my renderer the other day! I did it with vec4 tangents where the w component was the direction of the bitangent in raport to the cross product between the normal and the first 3 components. It is a bit more computationally expensive but saves some space. One thing I had some trouble with was the fact that the normal texture had to be in the UNORM format. I am adding this just in case other people encounter this issue. Also I am not sure if it is an issue in OpenGL. My renderer uses Vulkan

[@OGLDEV]

Thanks! When you sample the normal from the UNORM texture what is the range of the result components?

[@radueduard587]

@@OGLDEV Sorry i completely forgot about the comment. It is [0, 1] so i double it and subtract one to get the actual normal

[@OGLDEV]

So it doesn't really matter if you use a UNORM texture, right? Did you get it working eventually?

[@alejandro9609]

Ok..good job 👍

[@OGLDEV]

Thanks 👍