Surface shaders and UNITY_MATRIX_MVP

Hi friends,

Where is the multiplication by UNITY_MATRIX_MVP done in surface shaders?
I would like to overwrite it. Is there a way I can do this in a surface shader?
If not possible, does someone still have the old shaders source code?

http://unity3d.com/support/old-resources/assets/built-in-shaders has the new shaders only

 

you can have your own vertex function, so you can output whatever you want for your surface frag yourself. No need to mess with other stuff.

 

Thank you Aubergine, but since there is no example, I don't know how to do it
I know that I can have my own vertex function, but unity will multiply by UNITY_MATRIX_MVP behind the scenes it seems?
Ideally, I want to multiply by my own matrix and not UNITY_MATRIX_MVP.
I guess I could manipulate the vertices by something like inverse of UNITY_MATRIX_MPV * MATRIX_I_WANT_TO_USE
if I want to use surface shaders.

 

what exactly do you want to do?

 

In a vertex shader, I want to say:

Code (csharp):

1.  
2. v2f vert(a2v IN)
3. {
4.    v2f OUT;
5.     OUT.pos = mul(_ProjMatrix, IN.vertex);
6.     return OUT;
7. }
8.  

where _ProjMatrix is my own MVP matrix that I supply through script.

Can I do this in a surface shader?
I know that in a surface shader I can manipulate the vertices like so:

Code (csharp):

1.  
2.   void vert (inout appdata_full v) {
3.     v.vertex = mul(_ProjMatrix, v.vertex);
4.       }
5.  

but unity will then multiply by UNITY_MATRIX_MPV after that.
Like I said above, I can make _ProjMatrix be (Inverse of UNITY_MATRIX_MPV) * MATRIX_I_WANT, so when unity mulpilies it will end up using MATRIX_I_WANT, but I don't want to do this, since I am afraid I will run into precision problems by taking the inverse.

I hope this is clear.

 

I'm trying something similar. I'm not there yet. The closest I've gotten is setting up a script on a camera, and in OnPreRender, I have::

Code (CSharp):

1.       Matrix4x4 world = transform.localToWorldMatrix;
2.         Matrix4x4 view = _cam.worldToCameraMatrix;
3.         Matrix4x4 proj = _cam.projectionMatrix;
4.  
5.  
6.         Matrix4x4 gpuProj = GL.GetGPUProjectionMatrix(proj, renderTextureIsTarget);
7.         Matrix4x4 gpuMV = view * world; // UNITY_MATRIX_MV
8.         Matrix4x4 gpuMVP = gpuProj * view *world; // UNITY_MATRIX_MVP
9.  
10.    
11.         _inverseMVP = gpuMVP.inverse;
12.         Shader.SetGlobalMatrix(_inverseMVPHash, _inverseMVP);

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But unfortunately, when I use this in a surface shader:

Code (CSharp):

1.  
2.         void vert (inout appdata_full v) {
3.                  float4 modelToCamera =  mul(UNITY_MATRIX_MVP, v.vertex);
4.                 float4 camAndBackAgain = mul(_InverseMVP, modelToCamera);
5.              
6.                 v.vertex = camAndBackAgain;
7.              
8.         }

(This just applies MVP and then unapplies it, I hope? It's just a sanity check)

It seems to add a couple of 90 degree turns somewhere?