script to send collision data to shader ?

hello guys,
i sware i browsed the forums for an answer, testes some codes, but all went with errors...

could someone point me to a script for U5 that detects and sends colision data to a shader please?

thanks mils

 

i started with this code
and it detects collision in playmode, i can print point values but the shader doesn't receive them

Code (CSharp):

1.  
2. using UnityEngine;
3. using System.Collections;
4.  
5. public class VegetationCollision : MonoBehaviour {
6.  
7.     void OnCollisionEnter(Collision collisionInfo) {
8.         ContactPoint contact = collisionInfo.contacts[0];
9.         collisionInfo.gameObject.GetComponent<Renderer>().material.SetVector ("_CollisionPoint", contact.point);
10.         collisionInfo.gameObject.GetComponent<Renderer>().material.SetVector ("_CollisionNormal", contact.normal);
11.         Debug.DrawRay(contact.point, contact.normal, Color.white);
12.         print (collisionInfo.gameObject.name+ "collided");
13.         //print(collisionInfo.gameObject.name + " and " + collisionInfo.collider.name + " are still colliding");
14.  
15.  
16.     }
17. }

 

and the shader i use.. just to detect point.., script detects collision
but nothing happens, seems like nor value is passed from the script to the shader

Code (CSharp):

1.  Shader "Custom/detections/collision_detection" {
2. Properties {
3.         _CollisionPoint ("Collision point", Vector) = (0, 0, 0,1)
4.         _CollisionNormal ("Collision normal", Vector) = (0, 0, 0,1)
5.  
6.         _Color ("Color (RGBA)", Color) = (0, 1, 0.5, 1)
7.      }
8.      SubShader {
9.          Tags { "Queue" = "Transparent" "RenderType" = "Transparent" }
10.          LOD 2000
11.          Cull Back
12.    
13.          CGPROGRAM
14.            #pragma surface surf Lambert vertex:vert alpha
15.            #pragma target 3.0
16.    
17.           struct Input {
18.              float3 worldPos;
19.              float4 vertPos;
20.            };
21.    
22.  
23.            float4 _Color;
24.            float4 _CollisionPoint, _CollisionNormal;
25.            float4 localCollision;
26.    
27.            void vert (inout appdata_full v, out Input o)
28.            {
29.                 UNITY_INITIALIZE_OUTPUT(Input,o);
30.                 o.vertPos = v.vertex;
31.            }
32.    
33.            void surf (Input IN, inout SurfaceOutput o) {
34.          
35.             //localCollision = mul(_Object2World, IN.vertPos);
36.             o.Albedo = _CollisionPoint.xyz;
37.             o.Alpha=1;
38.            }
39.    
40.            ENDCG
41.      }
42.      Fallback "Transparent/Diffuse"
43. }
44.  

 

Just guessing;
you should use sharedMaterial instead of material in your script
and
you should change the contactpoint vector to object space before sending it to the shader.

Although it wont work as i guess you are trying to achieve some sort of shield effect but you will eventually see some colors on screen after you do the above.

 

Hi aubergine,
i tried sharedmaterial but nothing at all, same problem...
what i am trying to do can be used for various things ie vegetation collision, surface effects etc.
for now, i just want the color or the object to change so i'm sure to get the data.
then i wil manage collision point and normal in shader, unless it's faster in script.

could it be due to the fact that contact.point is a vector 3 ?
(tried to replace contact point with new vector4 (x,y,z,1) and didn't work either)

thanks for your help

 

like i said, change the contact point vector to local space relative to the object.
check the documents on transform.worldtolocalmatrix or inversetransformpoint.

 

thanks aubergine, will do that and get back here
thx mils

edit : from the docs
IMPORTANT: If you're setting shader parameters you MUST use Renderer.worldToLocalMatrix instead.
i don't know yet how to code that but still working on this

 

tried this, but nothing

Code (CSharp):

1.  
2.  ContactPoint contact = collisionInfo.contacts[0];
3.  Renderer rend = collisionInfo.gameObject.GetComponent<Renderer>();
4.  Vector4 localPoint = rend.worldToLocalMatrix.MultiplyPoint (contact.point);
5.  rend.material.SetVector("_CollisionPoint", localPoint);
6.  

 

I cant write code as i am selling something smiliar as a commercial asset.
However, here is some psuedo on how you can do it:

script:
if(object is hit somehow) get hit position vector
shader.sharedmaterial.setVector( "_Collision0", object.transform.inversetransformpoint(hit.position) )

shader:
vert() {
distance = v.vertex.xyz - transformedhitpoint.xyz; //probably normalized
}
frag() {
do some fancy stuff with the distance value
}

Next, you will want to send an array of hit point(s) as well as some array of timer(s) to the shader in order to get a nice shield effect.

 

hey aubergine thanks a lot mate, that's great, will test it asap
i'll help you back if i can
cheers

edit : that's not for a shield effect, more for surface effects (dust, bullets etc)

 

Same principle applies, anyways if you are still having trouble, you should check this package.

 

Hey @antislash, Did you able to figure it out ?