What do you want to happen? Is that one mesh in your example or is it a bunch of intersecting meshes. If it's a bunch of intersecting meshes do you want them to have one outline? What about other meshes? My point is you need some way to define which "groups" of meshes get a single outline if you're using multiple meshes.
For multiple meshes and one outline a common solution is to draw all the meshes in a single group to a render target to generate a silhouette, then post process the silhouette to expand it. Finally apply the silhouette to the scene. I don't know of a three.js example but the concept is explained here and there's also many references here
Another solution that might work, should be possible to move the outline shell back in Z so doesn't intersect. Either all the way back (Z = 1 in clip space) or back some settable amount. Drawing with groups so that a collection of objects in front has an outline that blocks a group behind would be harder.
For example if I take this sample that prisoner849 linked to
And change the vertexShaderChunk in OutlineEffect.js to this
var vertexShaderChunk = `
#include <fog_pars_vertex>
uniform float outlineThickness;
vec4 calculateOutline( vec4 pos, vec3 objectNormal, vec4 skinned ) {
float thickness = outlineThickness;
const float ratio = 1.0; // TODO: support outline thickness ratio for each vertex
vec4 pos2 = projectionMatrix * modelViewMatrix * vec4( skinned.xyz + objectNormal, 1.0 );
// NOTE: subtract pos2 from pos because BackSide objectNormal is negative
vec4 norm = normalize( pos - pos2 );
// ----[ added ] ----
// compute a clipspace value
vec4 pos3 = pos + norm * thickness * pos.w * ratio;
// do the perspective divide in the shader
pos3.xyz /= pos3.w;
// just return screen 2d values at the back of the clips space
return vec4(pos3.xy, 1, 1);
}
`;
It's easier to see if you remove all references to reflectionCube and set the clear color to white renderer.setClearColor( 0xFFFFFF );
Original:
After:
