Hi, I'm doing a retro style game and I'm using this "Playstation 1 style" vertex snapping shader on my meshes, it works perfectly fine with shadows off, but with shadows turned on all the shadows are glitched:

I can sort of see why this shader would break shadows, (actual old games didn't have shadows like that either obviously), but I don't know enough about Godot to know if there's any easy fix for this issue. With this game my aim is to have the game look retro but with a couple of little modern enhancements (instead of, like, a 1:1 playstation/nintendo 64 looking game), and being able to use shadows as normal would really help with that idea.

Here's the code:

shader_type spatial;
render_mode vertex_lighting, skip_vertex_transform, 
			specular_schlick_ggx, diffuse_lambert_wrap;
 
uniform sampler2D albedo: hint_default_black, filter_nearest, repeat_enable; 
uniform sampler2D specular: hint_default_black;
uniform sampler2D emission: hint_default_black;

uniform float jitter: hint_range(0.0, 1.0) = 0.5;
uniform bool jitter_z_coordinate = true;
uniform bool jitter_depth_independent = true;
uniform bool affine_texture_mapping = true;
uniform float alpha_scissor: hint_range(0.0, 1.0) = 1.0;
 
void vertex() {
	VERTEX = (MODELVIEW_MATRIX * vec4(VERTEX, 1.0)).xyz;
 
	float z_orig = VERTEX.z;
	float i = (1.0 - jitter) * min(VIEWPORT_SIZE.x, VIEWPORT_SIZE.y) / 2.0;
 
	if (jitter_depth_independent) {
		float w = (PROJECTION_MATRIX * vec4(VERTEX, 1.0)).w;
		VERTEX = round(VERTEX / w * i) / i * w;
	} else {
		VERTEX = round(VERTEX * i) / i;
	}
 
	if (!jitter_z_coordinate) {
		VERTEX.z = z_orig;
	}
 
	if (affine_texture_mapping) {
		UV *= VERTEX.z;
	}
}
 
void fragment() {
	vec2 uv = UV;
 
	if (affine_texture_mapping) {
		uv /= VERTEX.z;
	}
 
	ALBEDO = texture(albedo, uv).rgb;
	ALPHA = texture(albedo, uv).a;
	ALPHA_SCISSOR_THRESHOLD = alpha_scissor;
	EMISSION = texture(emission, uv).rgb;
	SPECULAR = texture(specular, uv).r;
}

Any help would be greatly appreciated!