Vertex Color RGB Material Blender

A fork of @spamrakuen‘s ORM vertex color blender.

Using a mesh that has been painted with vertex colors, the red, greens and blues will be repalced with ORM materials you assign. Blending can be adjsuted in several ways. This fork isn’t far from the original, I’ve only added another color channel/material and added a few more sliders sliders let you adjust the ORM AO, Roughness, and Metallic levels after the fact as well.

Shader code

shader_type spatial;
render_mode blend_mix, depth_draw_opaque, cull_back, diffuse_burley, specular_schlick_ggx;

// Textures for material A, B, C, and the transition noise
group_uniforms textures;
uniform sampler2D texture_albedo_a : source_color, filter_linear_mipmap, repeat_enable;
uniform sampler2D texture_orm_a : hint_roughness_g, filter_linear_mipmap, repeat_enable;
uniform sampler2D texture_normal_a : hint_roughness_normal, filter_linear_mipmap, repeat_enable;

uniform sampler2D texture_albedo_b : source_color, filter_linear_mipmap, repeat_enable;
uniform sampler2D texture_orm_b : hint_roughness_g, filter_linear_mipmap, repeat_enable;
uniform sampler2D texture_normal_b : hint_roughness_normal, filter_linear_mipmap, repeat_enable;

uniform sampler2D texture_albedo_c : source_color, filter_linear_mipmap, repeat_enable;
uniform sampler2D texture_orm_c : hint_roughness_g, filter_linear_mipmap, repeat_enable;
uniform sampler2D texture_normal_c : hint_roughness_normal, filter_linear_mipmap, repeat_enable;

uniform sampler2D texture_noise : source_color, filter_linear_mipmap, repeat_enable;

group_uniforms main_settings;
uniform vec4 albedo_a : source_color = vec4(1.0, 1.0, 1.0, 1.0);
uniform vec4 albedo_b : source_color = vec4(1.0, 1.0, 1.0, 1.0);
uniform vec4 albedo_c : source_color = vec4(1.0, 1.0, 1.0, 1.0);
uniform float normal_scale : hint_range(-16, 16) = 1.0;
uniform float ao_light_affect = 1.0;
uniform float roughness_control : hint_range(0, 2) = 1.0;
uniform float metallic_control : hint_range(0, 2) = 1.0;
uniform vec3 uv1_scale = vec3(1.0, 1.0, 1.0);
uniform vec3 uv1_offset;

group_uniforms blend_settings;
uniform float blend_threshold = 0.5;
uniform float blend_noise_intensity = 0.5;
uniform float blend_noise_scale = 2.0;
uniform float blend_softness = 0.5;
uniform vec4 blend_transition_color : source_color = vec4(0.0, 0.0, 0.0, 0.25);

void vertex() {
    UV = UV * uv1_scale.xy + uv1_offset.xy;
}

void fragment() {
    vec2 base_uv = UV;
    vec2 noise_uv = UV * blend_noise_scale;

    float mask_a = COLOR.r;
    float mask_b = COLOR.g;
    float mask_c = COLOR.b;

    float noise = texture(texture_noise, noise_uv).r * blend_noise_intensity;
    float threshold = clamp(blend_threshold + noise, 0.0, 1.0);

    float blend_a = smoothstep(threshold - blend_softness, threshold + blend_softness, mask_a);
    float blend_b = smoothstep(threshold - blend_softness, threshold + blend_softness, mask_b);
    float blend_c = smoothstep(threshold - blend_softness, threshold + blend_softness, mask_c);

    float total_blend = blend_a + blend_b + blend_c;
    if (total_blend > 0.0) {
        blend_a /= total_blend;
        blend_b /= total_blend;
        blend_c /= total_blend;
    } else {
        blend_a = 1.0; // Avoid black spots by defaulting to material A
    }

    vec4 albedo_tex_a = texture(texture_albedo_a, base_uv) * albedo_a;
    vec4 albedo_tex_b = texture(texture_albedo_b, base_uv) * albedo_b;
    vec4 albedo_tex_c = texture(texture_albedo_c, base_uv) * albedo_c;

    vec3 albedo_mixed = albedo_tex_a.rgb * blend_a +
                         albedo_tex_b.rgb * blend_b +
                         albedo_tex_c.rgb * blend_c;

    float transition = clamp(1.0 - smoothstep(blend_softness * 0.5, blend_softness * 1.5, abs(mask_a - threshold)), 0.0, 1.0);
    vec3 transition_visual = mix(albedo_mixed.rgb, blend_transition_color.rgb, transition * min(blend_transition_color.a, 0.5));
    ALBEDO = transition_visual;

    vec4 orm_tex_a = texture(texture_orm_a, base_uv);
    vec4 orm_tex_b = texture(texture_orm_b, base_uv);
    vec4 orm_tex_c = texture(texture_orm_c, base_uv);

    ROUGHNESS = (orm_tex_a.g * blend_a +
             orm_tex_b.g * blend_b +
             orm_tex_c.g * blend_c) * roughness_control;

    METALLIC = (orm_tex_a.b * blend_a +
            orm_tex_b.b * blend_b +
            orm_tex_c.b * blend_c) * metallic_control;

    vec3 normal_map_a = texture(texture_normal_a, base_uv).rgb;
    vec3 normal_map_b = texture(texture_normal_b, base_uv).rgb;
    vec3 normal_map_c = texture(texture_normal_c, base_uv).rgb;

    vec3 normal_mixed = normal_map_a * blend_a +
                        normal_map_b * blend_b +
                        normal_map_c * blend_c;

    NORMAL_MAP = normal_mixed;
    NORMAL_MAP_DEPTH = normal_scale;

    AO = orm_tex_a.r * blend_a +
         orm_tex_b.r * blend_b +
         orm_tex_c.r * blend_c;

    AO_LIGHT_AFFECT = ao_light_affect;
}

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