Vulkan: Fixed Fog is no longer radial and fades according to the view plane instead

[mrjustaguy]

Godot version

v4.0.dev.custom_build [5a612d6]

System information

Windows 10, Vulkan, Nvidia Quadro K2000 461.92

Issue description

Fog is no longer radial, as opposed to Fog in 3.x

(3.x)

In 3.x, the Fog fade is like in the picture, while in 4.0 the Fog fades in a linear fashion (like the camera far cuts off, also visible in the picture)

The Radial Fog is important because the angle of the camera doesn't affect how foggy something is, only distance matters, while without Radial Fogs rotating a camera can reveal things that are supposed to be foggy

Steps to reproduce

Create a Scene with Fogs in 3.x and Master and observe the behaviors of the 2 Fogs when rotating the camera with objects in the Fog

In Master, the fog level of objects will change as the camera rotates, but in 3.x it will not.

Minimal reproduction project

No response

[clayjohn]

I guess the difference is just that in 3.x we us the distance to a given point while in 4.0 we just use the camera-space z value

GLES3:

godot/drivers/gles3/shaders/scene.glsl

Line 2231 in 1cbb1f2

float fog_z = smoothstep(fog_depth_begin, fog_far, length(vertex));

Master:

godot/servers/rendering/renderer_rd/shaders/scene_forward_clustered.glsl

Line 527 in f77b1f4

float fog_amount = 1.0 - exp(min(0.0, vertex.z * scene_data.fog_density));

Note for whoever works on this:
Fog in master is calculated in multiple places:

• scene_forward_clustered.glsl
• scene_forward_mobile.glsl and
• sky.glsl