1 files changed, 40 insertions, 0 deletions
diff --git a/source/blender/draw/modes/shaders/object_outline_prepass_geom.glsl b/source/blender/draw/modes/shaders/object_outline_prepass_geom.glsl
new file mode 100644
index 00000000000..c90195e11fd
--- /dev/null
+++ b/source/blender/draw/modes/shaders/object_outline_prepass_geom.glsl
@@ -0,0 +1,40 @@
+
+layout(lines_adjacency) in;
+layout(line_strip, max_vertices = 2) out;
+
+uniform mat4 ProjectionMatrix;
+
+in vec4 pPos[];
+in vec3 vPos[];
+
+void main()
+{
+	bool is_persp = (ProjectionMatrix[3][3] == 0.0);
+
+	vec3 view_vec = (is_persp) ? normalize(vPos[1]) : vec3(0.0, 0.0, -1.0);
+
+	vec3 v10 = vPos[0] - vPos[1];
+	vec3 v12 = vPos[2] - vPos[1];
+	vec3 v13 = vPos[3] - vPos[1];
+
+	vec3 n0 = cross(v12, v10);
+	vec3 n3 = cross(v13, v12);
+
+	float fac0 = dot(view_vec, n0);
+	float fac3 = dot(view_vec, n3);
+
+	/* If both adjacent verts are facing the camera the same way,
+	 * then it isn't an outline edge. */
+	if (sign(fac0) == sign(fac3))
+		return;
+
+	/* Don't outline if concave edge. */
+	/* That would hide a lot of non usefull edge but it flickers badly.
+	 * TODO revisit later... */
+	// if (dot(n0, v13) > 0.01)
+	// 	return;
+
+	gl_Position = pPos[1]; EmitVertex();
+	gl_Position = pPos[2]; EmitVertex();
+	EndPrimitive();
+}