Dirt Cleaning Shader
Hey everyone.
This is updated for Godot 4.3
This shader simulates cleaning a surface of a plane for a “Dirt Cleaning” effect.
After searching online for a while I coudn’t find any other tutorials that seemed to be straight forward for a simple plane so I made this.
It works by using a Collider for the plane, passing a raycast at the mouse coordinates, then translating those coordinates to local coordinates to the plane mesh. Then drawing on a mask and giving the new mask to the shader to remove the dirt.
You will have to modify how collision is handled most likely for your game.
I also added a way to calculate how much of the dirt has been cleaned.
Shader code
shader_type spatial;
uniform sampler2D clean_texture;
uniform sampler2D dirty_texture;
uniform sampler2D dirt_mask;
// Control for the amount of dirtiness applied
uniform float dirt_strength : hint_range(0.0, 1.0);
void fragment() {
// Sample colors from the clean and dirty textures
vec4 clean_color = texture(clean_texture, UV);
vec4 dirty_color = texture(dirty_texture, UV);
// Sample the dirt mask (typically a grayscale texture)
float mask_value = texture(dirt_mask, UV).r;
// Adjust the mask by dirt_strength to control the blending
float adjusted_mask = mask_value * dirt_strength;
// Final blend factor considering both the mask and the dirty texture's alpha
float blend_factor = adjusted_mask * dirty_color.a;
// Blend the clean and dirty colors, preserving some of the clean texture's influence
vec4 final_color = mix(clean_color, dirty_color, blend_factor);
// For ALPHA, use the higher of clean or dirty alpha to ensure visibility
ALBEDO = final_color.rgb;
ALPHA = max(clean_color.a, blend_factor);
}
