How to get worldPos in fragment shader

How can we get worldPos in a fragment shader?
I know that it is available in surface shaders, but I need it in a fragment shader.

thanks

 

This looks correct. Copy-paste from the Internal-PrePassLighting Shader.

Code (csharp):

1.  
2. Shader "WorldPos" {
3. Properties {
4.     _MainTex ("Base (RGB)", 2D) = "white" {}
5. }
6.  
7. SubShader {
8.     Pass {
9.  
10.    
11. CGPROGRAM
12. #pragma vertex vert
13. #pragma fragment frag
14. #include "UnityCG.cginc"
15.  
16. uniform sampler2D _MainTex;
17.  
18. struct appdata {
19.     float4 vertex : POSITION;
20.     float3 texcoord : TEXCOORD0;
21. };
22.  
23. struct v2f {
24.     float4 pos : SV_POSITION;
25.     float4 uv : TEXCOORD0;
26.     float3 ray : TEXCOORD1;
27. };
28.  
29.  
30.  
31. v2f vert (appdata v)
32. {
33.     v2f o;
34.     o.pos = mul(UNITY_MATRIX_MVP, v.vertex);
35.     o.uv = ComputeScreenPos (o.pos);
36.     o.ray = mul (UNITY_MATRIX_MV, v.vertex).xyz * float3(-1,-1,1);
37.    
38.     // v.texcoord is equal to 0 when we are drawing 3D light shapes and
39.     // contains a ray pointing from the camera to one of near plane's
40.     // corners in camera space when we are drawing a full screen quad.
41.     o.ray = lerp(o.ray, v.texcoord, v.texcoord.z != 0);
42.    
43.     return o;
44. }
45.  
46. sampler2D _CameraDepthTexture;
47. float4x4 _CameraToWorld;
48. float3 _clipPoint;
49. float3 _clipNormal;
50.  
51. half4 frag (v2f i) : COLOR
52. {
53.     i.ray = i.ray * (_ProjectionParams.z / i.ray.z);
54.     float2 uv = i.uv.xy / i.uv.w;
55.    
56.     float depth = UNITY_SAMPLE_DEPTH(tex2D (_CameraDepthTexture, uv));
57.     depth = Linear01Depth (depth);
58.     float4 vpos = float4(i.ray * depth,1);
59.     float3 wpos = mul (_CameraToWorld, vpos).xyz;
60.    
61.     return half4(wpos,1.0f);
62.    
63. }
64.  
65. ENDCG
66. }
67.  
68. }
69. Fallback Off
70. }
71.  

don't forget to set your camera to render the depth texture

Code (csharp):

1.  
2. camera.depthTextureMode = DepthTextureMode.Depth;
3.  

I still want to know if there are other ways to do it. How is worldPos calculated in surface shaders.

 

worldpos = mul(_ObjectToWorld, vertex)

 

I want the world position associated with the fragment.

I still want to know if there are other ways to do it. How is worldPos calculated in surface shaders?

 

Aubergine, would you know how to pass the

Code (csharp):

1.  
2. worldpos = mul(_ObjectToWorld, vertex);
3.  

to the fragment shader?
I understand that this is the vertex position in world space, however I really don't know how shaders actually work.
If I pass somehow (TEXCOORD?) the vertices world positions, would the fragments world positions be automatically computed for me?
Looks like it should: The easiest way is to pass the world-position down from the vertex shader via a varying variable
But how exactly would I do this?

 

You just pass it through the input structure, but the above "worldpos" can not compute anything automatically for you. Its up to you to use it however you want. Unless you bind it to POSITION or somethin.

 

Thank you sir. I believe I got it. I will bind it to something like COLOR or TEXCOORD, and then it would be linearly interpolated for me by the rasterizer. I will try this when I get a chance.

 

It does work. But more importantly, the process through which fragments are computed is not a black box any more. Just a gray box. Dark gray box.

thanks again Aubergine

 

Welcome to my grey box

 

To anyone stumbling onto this old post: Ivkoni above posted the following line:

Code (CSharp):

1. worldpos = mul(_ObjectToWorld, vertex);

This contains an error, it should be written as:

Code (CSharp):

1. worldpos = mul(_Object2World, vertex);

Thanks for helping me out.

​

 

...and since then Unity has changed it again (saw this page from google hits trying to check something else, it's a top hit, so worth necroing). 2019 version is:

mul( unity_ObjectToWorld, vertex ) // see Unity docs top of this page for latest: https://docs.unity3d.com/Manual/SL-UnityShaderVariables.html

(where "vertex" is usually in.vertex / IN.vertex etc, whatever you named your appdata_full parameter to your vertex-shader method).

PS: I prefer the new name. It's clear (it tells you it's data supplied specifically by Unity), and it gets rid of the ugly, incorrect, use of "2" (digits in GL/HLSL/GLSL functions and vars have specific meaning, it's a bad idea to use them to mean something else too).

 

Thank you!