Godot 4.0: Wrong VIEW vector in light() shader

[alekseym88]

Godot version

4.0.dev (84c404f), and same for 4.0b4

System information

MacOS Monterey 12.0.1, Intel Iris Graphics 550 1536 MB

Issue description

For orthogonal camera, VIEW vector in light() part of shader should be equal vec3(0.0, 0.0, 1.0), but in real this vector has different direction

Steps to reproduce

Add camera, sphere and source of light in your project, add this shader to sphere:

shader_type spatial;

void light() {
	DIFFUSE_LIGHT += vec3( pow( dot(VIEW, NORMAL), 3.0) );
}

in editor result will be fine:

but in camera view:

As a temporary solution can use just vector vec3(0.0, 0.0, 1.0) instead VIEW

Minimal reproduction project

test_view.7z.zip

[Chaosus]

I think it's related to the position of Spotlight in your scene. Try to cover the geometry by the light volume completely and the bug will be gone.

[alekseym88]

Even it will be fully cover, VIEW vector is still remain wrong

[Chaosus]

Ah, yes, but there is not much we can do with it. Maybe detecting the orthogonality of the camera in the scene shader and replace the VIEW to vec3(0, 0, 1) ? (I'm afraid it's too performance consuming for the little benefit). cc @clayjohn

[alekseym88]

@Chaosus i think this solution is ok, its not a big problem to use just a vec3(0, 0, 1), but i think in this case better update this info in docs.godotengine.org, as it will be not so obvious for some people

[Chaosus]

Right, marked as documentation issue ^^.

[clayjohn]

It looks like there was a lot of discussion about this on the Three.js github mrdoob/three.js#17662 They ended up switching it so that orthogonal cameras use a VIEW vector of vec3(0, 0, 1). As far as I can tell, both Unity and Unreal use the same VIEW vector for both perspective and orthogonal cameras.

It seems a VIEW vector of vec3(0, 0, 1) for orthogonal cameras is more "correct" in a certain sense. Oddly enough, when setting the viewport camera to "orthogonal" mode the VIEW vector is always vec3(0.0, 0.0, 1.0), I guess that it is set at a distance away from the origin sufficient that the VIEW vector is effectively always vec3(0.0, 0.0, 1.0).

I wonder if any people are currently relying on the current "incorrect" behaviour. If no one is, then I don't mind changing the VIEW vector to vec3(0, 0, 1) for orthogonal cameras

[tetrapod00]

This was documented in godotengine/godot-docs#8708. Are we leaving this open to track potentially changing the actual behavior, or can it be closed?