Problem with bending terrain shader

Hi, I'm having trouble with a shader that should curve the terrain. The problem is that the objects with this shader act differently according to their rotation. For example, I have a long corridor and a set of 3 spheres. If all of the GOs have zero rotation, everything looks fine. But if I change the rotation of one of those spheres, it goes up and down, and I don't want that, since sometimes the scene looks all messed up. Here are some pics illustrating this problem:


Here with higher quality: http://i.imgur.com/BncqIk7.png

And this is the shader itself:

Code (csharp):

1.  
2. Shader "Mobile/Curved" {
3. Properties {
4.     _MainTex ("Base (RGB)", 2D) = "white" {}
5.     _QOffset ("Offset", Vector) = (0,0,0,0)
6.     _Dist ("Distance", Float) = 100.0
7. }
8. SubShader {
9.     Tags { "RenderType"="Opaque" }
10.     LOD 150
11.  
12.     CGPROGRAM
13.     #pragma exclude_renderers flash
14.     #pragma surface surf Lambert noforwardadd vertex:vert
15.    
16.     sampler2D _MainTex;
17.     float4 _QOffset;
18.     float _Dist;
19.    
20.     struct Input {
21.         float2 uv_MainTex;
22.     };
23.    
24.     void vert (inout appdata_full v) {
25.         // Get the view space vertex position
26.         float4 vertex_view = mul(UNITY_MATRIX_MV, v.vertex);
27.         // Calculate the offset in view space
28.         float zOff = vertex_view.z / _Dist;
29.         // Convert the offset back to object space and add it to vertex
30.         v.vertex.xyz += mul(UNITY_MATRIX_IT_MV, _QOffset*zOff*zOff).xyz;
31.     }
32.    
33.     void surf (Input IN, inout SurfaceOutput o) {
34.         fixed4 c = tex2D(_MainTex, IN.uv_MainTex);
35.         o.Albedo = c.rgb;
36.         o.Alpha = c.a;
37.     }
38.    
39.     ENDCG
40. }
41.  
42. Fallback "Mobile/VertexLit"
43. }
44.  

I hope you can help me, I really need to get this fixed! Thank you very much!

 

Can anyone help me, please?

 

If you want to send back the vertices you dont need to transpose, just do the inverse. As for your rotation problem, are you sure its the shader? does it rotate properly with a regular diffuse? Anyways try to remove the transpose might fix your issue.

 

_QOffset is a parameter, it's configurable. The multiplication by UNITY_MATRIX_IT_MV is for getting back to object space. I thought it was the correct way to covert from view to object space, am I missing something? As far as I know, there's no built in matrix for modelview inversed and not transposed, is it? https://docs.unity3d.com/Documentation/Components/SL-BuiltinValues.html
How can I do what you guys suggest?

 

I think you'd need to do the bending in world space, then put it back into object space.

Otherwise all of the positions/rotations values are relative to the object's origin, rather than a constant point (world origin).

 

I think he wants to do the bending based on the camera's position, thats why the changes are made in the view matrix, so they are relative to the camera's position. As for getting just the inverse, to revert a transpose, you just transpose again. Inversing is not enabled in unity's implementation of CG , its a much more demanding operation than transposing, so you can just transpose the IT_MV and youll get the I_MV basically. Hope that helps.

 

It would definetly help if he posted what type of game this was, view space modification would work if it was an infinite runner for example where rotation of the camera doesn't really happen. But that is more on topic of game design than anything else.

 

Well, the game is indeed an infinite runner, that's why the bending is calculated in view space. I'm not quite sure if a bending in world space would give the same results (as you can see, I'm no expert in shaders...). So, with that being said, do you recommend to do the bending in world or view space?

 

Ok guys, I've replaced

Code (csharp):

1. v.vertex.xyz += mul(UNITY_MATRIX_IT_MV, _QOffset*zOff*zOff).xyz;

by

Code (csharp):

1. v.vertex.xyz += mul(_QOffset*zOff*zOff, UNITY_MATRIX_IT_MV).xyz;

in order to not transpone the matrix, and now everything looks fine. I can't assure it will in every situation though, but I think it's ok now!
If anyone is interested in why I started by bending in view space, it's because that way all game calculations are made as if the path is completely straight. The camera is only rotating in the corners, but it does it quickly and there's no noticeable deformation.
Thank you very much guys, I appreciate your help!

 

Subway surfers did the exact same thing in their game.

 

Hi, This Shader works great!! Can anyone help me on how to make it as a unlit and unlit transparent shader.

Thanks