Light / shadow acting the wrong way on an imported mesh

Question

I've recently made a quick scene with some light tests, using GIProbes / directional light and some environment config.

And I've tried importing different mesh types into that scene, a voxel based one, which works perfectly fine, and another one with a more complex shape, and the shadows/lights looks wrong.. It looks like the direction is wrong, maybe this is caused by my mesh itself, I don't really know..

Comments

HI,
the shadow is just right.
The shading looks wrong. I would guess the normals of the mesh are inverted.
This often happens if you mirror meshes in a 3D editors.

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Yeah, you just need to flip the Normals of certain faces in your 3d modelling software. You can visualise them as red and blue in blender in the view settings.

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Thank you for your quick answer.
Here's how my mesh looks like in blender, normals doesn't seems to be wrong to me, or am I missing something?

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Hi,
can you check the scaling? Some editors just invert the scale (-100%) to mirror.
Wich is technical correct but often results in odd behaviour in realtime rendering.

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Blender scale export is 1:1
On my scene it's also looking good, I don't think the scaling is wrong

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How about checking it with a "normal shader"

make a new shader material:

shader_type spatial;
render_mode vertex_lighting, unshaded;

varying vec3 c;

void vertex() {
    c.rgb = ((WORLD_MATRIX * vec4(NORMAL.rgb,0.0)).xyz /2.0 + 0.5);
}

void fragment(){
    ALBEDO.rgb = abs(c);
}

This shows the "true" normals when rendering.
Compare it with a "normal" mesh thats looks alright with the same shader.

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Thank for the advice, this helped me realize that it's a problem with my scene and not the mesh itself, I've tried multiple obj files and they all have this shading problem at the same agnle..

I'm looking forward to find a solution, or maybe you guys can help me about this?
Thanks for the help!

Here how the two object normals renders with the shader

and here without the shader

Answer 1

I find out the issue, it was really stupid, and cause by the Bias in the Shadow option of my directional light, the value was at -2 (???) And cause the shadow render to be totally messed up.

Thanks to everyone who helped!