Godot Version
4.5.stable
Question
Hi guys, I am having a bit of trouble working with a sobel edge detection shader. When two meshes are just next to each other or overlapping, the hidden edge generates some artifacts:
The SobelPostProcess node is just a MeshInstance3D with a shader material:
shader_type spatial;
render_mode unshaded, depth_test_disabled, depth_draw_never, cull_disabled;
uniform sampler2D screen_texture: hint_screen_texture;
uniform sampler2D depth_texture: hint_depth_texture;
uniform sampler2D normal_texture: hint_normal_roughness_texture;
uniform vec3 outline_color: source_color;
uniform float outline_threshold = 0.2;
const float sobel_x[8] = float[](
-1.0, 0.0, 1.0,
-2.0, 2.0,
-1.0, 0.0, 1.0
);
const float sobel_y[8] = float[](
-1.0, -2.0, -1.0,
0.0, 0.0,
1.0, 2.0, 1.0
);
const vec2 offset[8] = vec2[](
vec2(-1, -1), vec2( 0, -1), vec2( 1, -1),
vec2(-1, 0), vec2( 1, 0),
vec2(-1, 1), vec2( 0, 1), vec2( 1, 1)
);
vec3 get_view_pos(vec2 uv, float depth, mat4 inv_proj_m){
vec4 ncd = vec4((uv*2.0)-1.0,depth,1.0);
vec4 veiw_pos = inv_proj_m*ncd;
return veiw_pos.xyz /= veiw_pos.w;
}
void vertex() {
POSITION = vec4(VERTEX.xy, 1.0, 1.0);
}
void fragment() {
vec2 uv = SCREEN_UV;
vec2 texel = 1.0 / vec2(textureSize(depth_texture, 0));
vec3 screen_color = texture(screen_texture, uv).rgb;
mat4 inv_proj_m = INV_PROJECTION_MATRIX;
float center_depth = texture(depth_texture, uv).r;
vec3 center_view = get_view_pos(uv, center_depth, inv_proj_m);
vec3 center_normal = texture(normal_texture, uv).rgb * 2.0 - 1.0;
float depth_edge_x = 0.0;
float depth_edge_y = 0.0;
float norm_edge_x = 0.0;
float norm_edge_y = 0.0;
for (int i = 0; i < 8; i++) {
vec2 neighbor_uv = clamp(uv + offset[i] * texel, vec2(0.0), vec2(1.0));
float neighbor_depth = texture(depth_texture, neighbor_uv).r;
vec3 neighbor_view = get_view_pos(neighbor_uv, neighbor_depth, inv_proj_m);
vec3 neighbor_normal = texture(normal_texture, neighbor_uv).rgb * 2.0 - 1.0;
float dist = distance(center_view, neighbor_view);
float diff = length(neighbor_normal - center_normal);
depth_edge_x += dist * sobel_x[i];
depth_edge_y += dist * sobel_y[i];
norm_edge_x += diff * sobel_x[i];
norm_edge_y += diff * sobel_y[i];
}
float depth_edge = sqrt(depth_edge_x * depth_edge_x + depth_edge_y * depth_edge_y)*10.0;
depth_edge = clamp(depth_edge, 0.0, 1.0);
float gradient = sqrt(norm_edge_x * norm_edge_x + norm_edge_y * norm_edge_y);
float normal_edge = float(gradient > outline_threshold);
float combined_edge = max(normal_edge, depth_edge);
ALBEDO = mix(screen_color, outline_color, combined_edge);
ALPHA = combined_edge;
}
This is the result on runtime (With an additional 1 bit shader I have down the pipeline):
Is there something I can do to alleviate this issue? Worst case scenario I’ll just plan around it but it would be great to have a solution.
Thank you very much in advance!