fix compatibility decal alpha

src/shaders/editor_functions.glsl

@@ -31,7 +31,7 @@ uniform sampler2D[3] _editor_decal : source_color, filter_linear, repeat_disable
 uniform vec2 _editor_decal_position[3];
 uniform float _editor_decal_size[3];
 uniform float _editor_decal_rotation[3];
-uniform vec3 _editor_decal_color[3] : source_color;
+uniform vec4 _editor_decal_color[3] : source_color;
 uniform bool _editor_decal_visible[3];
 
 // expects uv (Texture/world space 0 to +/- inf 1m units).
@@ -50,7 +50,7 @@ vec3 get_decal(vec3 albedo, vec2 uv) {
 			continue;
 		}
 		float decal = smoothstep(0.1,1.0,texture(_editor_decal[i],decal_uv + 0.5).r);
-		albedo =  mix(albedo, _editor_decal_color[i], clamp(decal * 0.25, 0.0, 0.25));
+		albedo =  mix(albedo, _editor_decal_color[i].rgb, decal * _editor_decal_color[i].a);
 	}
 
 	return albedo;