1 files changed, 37 insertions, 1 deletions
diff --git a/source/blender/draw/engines/overlay/shaders/outline_prepass_frag.glsl b/source/blender/draw/engines/overlay/shaders/outline_prepass_frag.glsl
index f6e3724eb51..85f79e94263 100644
--- a/source/blender/draw/engines/overlay/shaders/outline_prepass_frag.glsl
+++ b/source/blender/draw/engines/overlay/shaders/outline_prepass_frag.glsl
@@ -1,10 +1,46 @@
 
+uniform vec4 gpDepthPlane;
+
 flat in uint objectId;
 
 /* using uint because 16bit uint can contain more ids than int. */
 out uint outId;
 
+vec3 ray_plane_intersection(vec3 ray_ori, vec3 ray_dir, vec4 plane)
+{
+  float d = dot(plane.xyz, ray_dir);
+  vec3 plane_co = plane.xyz * (-plane.w / dot(plane.xyz, plane.xyz));
+  vec3 h = ray_ori - plane_co;
+  float lambda = -dot(plane.xyz, h) / ((abs(d) < 1e-8) ? 1e-8 : d);
+  return ray_ori + ray_dir * lambda;
+}
+
 void main()
 {
-  outId = objectId;
+#ifdef USE_GPENCIL
+  if (stroke_round_cap_mask(strokePt1, strokePt2, strokeAspect, strokeThickness, strokeHardeness) <
+      0.001) {
+    discard;
+  }
+
+  if (depth != -1.0) {
+    /* Stroke order 2D. */
+    bool is_persp = ProjectionMatrix[3][3] == 0.0;
+    vec2 uvs = vec2(gl_FragCoord.xy) * sizeViewportInv;
+    vec3 pos_ndc = vec3(uvs, gl_FragCoord.z) * 2.0 - 1.0;
+    vec4 pos_world = ViewProjectionMatrixInverse * vec4(pos_ndc, 1.0);
+    vec3 pos = pos_world.xyz / pos_world.w;
+
+    vec3 ray_ori = pos;
+    vec3 ray_dir = (is_persp) ? (ViewMatrixInverse[3].xyz - pos) : ViewMatrixInverse[2].xyz;
+    vec3 isect = ray_plane_intersection(ray_ori, ray_dir, gpDepthPlane);
+    vec4 ndc = point_world_to_ndc(isect);
+    gl_FragDepth = (ndc.z / ndc.w) * 0.5 + 0.5;
+  }
+  else {
+    gl_FragDepth = gl_FragCoord.z;
+  }
+#endif
+
+  outId = uint(objectId);
 }