Vertex shader creates gaps in models

I am using a shader to make trees (modeled and vertex painted in blender) look like they wave in the wind. The 3d-model of my tree has no holes and I have already checked for vertices occupying the same position in blender. For some reason my models get "disassembled" (see in the image attached) in unity when the shader is applied. I have no idea why this occurs. Does anyone know what i am doing wrong or how to fix it? Thx in advance

Code (csharp):

1.    
2. Shader "WavingDiffuse" {
3. Properties {
4.  _Color ("MainColor", Color) = (1,1,1,1)
5.  _Emission ("Emission", Color) = (0,0,0,1)
6.  _MainTex ("Base(RGB)", 2D) = "white" {}
7.  _Stiffness ("Stiffness" , Range( 1 , 2 ))= 1.0
8.  _WaveDirection ("WaveDirection" , Range(0 , 1)) = 1.0
9.  _WaveStrength ("WaveStrength" , Range( 0 , 0.1 ))= 0.02
10.  _WaveSpeed ("WaveSpeed" , Range( 0 , 20 ))= 6.0
11.  _WaveSize ("WaveSize" , Range( 0.1 , 5 ))= 1.0
12. }
13. SubShader {
14.  Tags { "RenderType"="Opaque"}
15.  LOD 200
16.  
17. CGPROGRAM
18. #pragma surface surf Lambert vertex:vert addshadow
19.  
20. sampler2D _MainTex;
21. fixed4 _Color;
22. fixed4 _Emission;
23. float _Stiffness;
24. float _WaveDirection;
25. float _WaveStrength;
26. float _WaveSpeed;
27. float _WaveSize;
28.  
29. struct Input {
30.  float2 uv_MainTex;
31. };
32.  
33. void vert (inout appdata_full v) {
34.  float multX = sin(_WaveDirection * 2 * 3.141592);
35.  float multZ = cos(_WaveDirection * 2 * 3.141592);
36.  float vp = ((multX * -v.vertex.x) + (multZ * -v.vertex.z))/ _WaveSize;
37.  float offset = _WaveStrength * pow(v.color.r, _Stiffness) *(
38.  (1 - sin(vp + _Time * 6 * _WaveSpeed)) +
39.  (1 - sin(vp + _Time * 9 * _WaveSpeed)) +
40.  (1 - sin(vp + _Time * 10 * _WaveSpeed))
41.  );
42.  v.vertex.x += multX * offset;
43.  v.vertex.z += multZ * offset;
44.  v.vertex.y -= sin(offset / 4);
45. }
46.  
47. void surf (Input IN, inout SurfaceOutput o) {
48.  fixed4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color;
49.  o.Albedo = c.rgb;
50.  o.Alpha = c.a;
51.  o.Emission = _Emission;
52. }
53. ENDCG
54. }
55.  
56. Fallback "VertexLit"
57. }
58. }

 

It seems that the vertex color must be to blame here. They might not be the same for all faces.

As a general note, even if something is 1 vertex in a modelling tool, it does not mean it's 1 vertex in a realtime application. Vertices are only shared if all properties are the same. (Position, normal, uvs, color.) Because of the flat shading, the normals are not the same and the vertices are split in this case. Every triangle will pretty much have 3 unique vertices in this model.

 

okay... So it doesn't seem like there is an easy soulution to the problem but thanks for your answer

 

The solution is to make sure the color you're using in the vertex shader looks "smooth" when unlit and not faceted.

 

Try to paint the vertex colors in unity.