Passing data to constants...

Is this feasible in a fragment program? For instance, I can do:

Local 0, [_Color0]

And then change _Color0 from scripting, but is there a performance hit to doing this? Like something has to get recompiled?

In that case, why can't I do something like:

Local 3, ([_SinTime],[_SinTime],[_CosTime],0)

Or all those only for Cg?

Thanks,
-Jon

 

Hi Aarku...

So good to finally see somebody getting turned into a shader developer ;-)

Yes... You set the constants from scripting. There is no performance hit.

SinTime is a 4-component vector property. So you would do Local 0, [_SinTime]

This will load up Local 0 with (sin (time *.125f), sin (time *.25f), sin(time * .5f), sin(time * 1f)), so you basically get 4 sine values oscillating at different speeds.

To choose one, you use component swizzling inside your fragment/vertex, e.g.
MOV r0, c0.rrrr; <- in the case of ATI_FRAGMENT.

Here is an example from Intifada; it loads up a bunch of values used in vertex/fragment programs:

Code (csharp):

1.  
2. using UnityEngine;
3. using System.Collections;
4.  
5. public class Atmosphere : MonoBehaviour {
6.     /// Gradient back and forth between rayleigh  mie scattering
7.     public float haze = 1f;
8.     public float hazeSunPwr = 2.5f;
9.     public float mist = 1f;
10.     public float mistSunPwr = 4f;
11.     public float mistDirectionality = .7f;
12.  
13.     Vector3 lightDirection = new Vector3 (0,-1,0);
14.     Color lightColor = Color.white;
15.  
16.     Light sunLight;
17.  
18.  
19.     void CalculateConstants () {
20.         // Get light values from the SunLight
21.         if (!sunLight) {
22.             GameObject go = GameObject.FindGameObjectWithTag ("SunLight");
23.             if (!go) {
24.                 Debug.LogError ("Atmosphere scattering requires a directional light tagged as SunLight");
25.                 return;
26.             }
27.             sunLight = go.GetComponent (typeof (Light)) as Light;
28.             if (!sunLight) {
29.                 Debug.LogError ("Atmosphere scattering requires a directional light tagged as SunLight");
30.                 return;
31.             }
32.         }
33.         lightColor = sunLight.color;
34.         lightDirection = sunLight.transform.TransformDirection (Vector3.forward);
35.    
36.         // Hard-coded color falloff coefficients
37.         Color betaRayleigh = new Color(0.58898305f, 1, 2.06779661f, 0) * .02f;
38.         Color betaMie = new Color(4e-7f, 6e-7f, 2.4e-6f, 0) * (1 / 1.18e-5f) * 2f * .02f * 1f;
39.  
40.         // wiegh them in and out
41.         betaRayleigh = betaRayleigh * haze;
42.         betaMie = betaMie * mist;
43.        
44.         // calculate constants for shader
45.         Color betaRayleighMie = betaRayleigh + betaMie;
46.         Color invBetaRayleighMie = 1f / betaRayleighMie;
47.        
48.         Color betaRayDash =  3f / (16f * 3.14159265f) * betaRayleigh * lightColor * hazeSunPwr;
49.         Color betaMieDash = 1 / (4f * 3.14159265f) * betaMie  * lightColor * mistSunPwr;
50.          
51.         Shader.SetColor ("_BetaRayleigh", betaRayleigh);
52.         Shader.SetColor ("_BetaMie", betaMie);
53.         Shader.SetColor ("_BetaRayleighMie", betaRayleighMie);
54.         Shader.SetColor ("_InvBetaRayleighMie", invBetaRayleighMie);
55.         Shader.SetColor ("_BetaRayDash", betaRayDash);
56.         Shader.SetColor ("_BetaMieDash", betaMieDash);
57.         Shader.SetColor ("_SunColor", sunLight.color);
58.         Vector3 lightDir = Vector3.Normalize (lightDirection);
59.         Shader.SetColor ("_LightDir", new Color (
60.             lightDir.x, lightDir.y, lightDir.z, 0));
61.        
62.         // HG Mie coefficients
63.         Shader.SetColor ("_GConst", new Color ((1-mistDirectionality) * (1-mistDirectionality), 1 + mistDirectionality* mistDirectionality, 2 * mistDirectionality,0));
64.     }
65.  
66.     // Update is called once per frame
67.     void LateUpdate () {
68.         CalculateConstants ();
69.     }
70.    
71.     void OnDrawGizmosSelected () {
72.         CalculateConstants ();
73.     }
74.     void OnDrawGizmos () {
75.         CalculateConstants ();
76.     }
77. }
78.  

This is much faster than calculating the stuff on every vertex or (gasp) every pixel.

 

Hi Aarku...

So good to finally see somebody getting turned into a shader developer ;-)

Yes... You set the constants from scripting. There is no performance hit.

SinTime is a 4-component vector property. So you would do Local 0, [_SinTime]

This will load up Local 0 with (sin (time *.125f), sin (time *.25f), sin(time * .5f), sin(time * 1f)), so you basically get 4 sine values oscillating at different speeds.

To choose one, you use component swizzling inside your fragment/vertex, e.g.
MOV r0, c0.rrrr; <- in the case of ATI_FRAGMENT.

Here is an example from Intifada; it loads up a bunch of values used in vertex/fragment programs:

Code (csharp):

1.  
2. using UnityEngine;
3. using System.Collections;
4.  
5. public class Atmosphere : MonoBehaviour {
6.     /// Gradient back and forth between rayleigh  mie scattering
7.     public float haze = 1f;
8.     public float hazeSunPwr = 2.5f;
9.     public float mist = 1f;
10.     public float mistSunPwr = 4f;
11.     public float mistDirectionality = .7f;
12.  
13.     Vector3 lightDirection = new Vector3 (0,-1,0);
14.     Color lightColor = Color.white;
15.  
16.     Light sunLight;
17.  
18.  
19.     void CalculateConstants () {
20.         // Get light values from the SunLight
21.         if (!sunLight) {
22.             GameObject go = GameObject.FindGameObjectWithTag ("SunLight");
23.             if (!go) {
24.                 Debug.LogError ("Atmosphere scattering requires a directional light tagged as SunLight");
25.                 return;
26.             }
27.             sunLight = go.GetComponent (typeof (Light)) as Light;
28.             if (!sunLight) {
29.                 Debug.LogError ("Atmosphere scattering requires a directional light tagged as SunLight");
30.                 return;
31.             }
32.         }
33.         lightColor = sunLight.color;
34.         lightDirection = sunLight.transform.TransformDirection (Vector3.forward);
35.    
36.         // Hard-coded color falloff coefficients
37.         Color betaRayleigh = new Color(0.58898305f, 1, 2.06779661f, 0) * .02f;
38.         Color betaMie = new Color(4e-7f, 6e-7f, 2.4e-6f, 0) * (1 / 1.18e-5f) * 2f * .02f * 1f;
39.  
40.         // wiegh them in and out
41.         betaRayleigh = betaRayleigh * haze;
42.         betaMie = betaMie * mist;
43.        
44.         // calculate constants for shader
45.         Color betaRayleighMie = betaRayleigh + betaMie;
46.         Color invBetaRayleighMie = 1f / betaRayleighMie;
47.        
48.         Color betaRayDash =  3f / (16f * 3.14159265f) * betaRayleigh * lightColor * hazeSunPwr;
49.         Color betaMieDash = 1 / (4f * 3.14159265f) * betaMie  * lightColor * mistSunPwr;
50.          
51.         Shader.SetColor ("_BetaRayleigh", betaRayleigh);
52.         Shader.SetColor ("_BetaMie", betaMie);
53.         Shader.SetColor ("_BetaRayleighMie", betaRayleighMie);
54.         Shader.SetColor ("_InvBetaRayleighMie", invBetaRayleighMie);
55.         Shader.SetColor ("_BetaRayDash", betaRayDash);
56.         Shader.SetColor ("_BetaMieDash", betaMieDash);
57.         Shader.SetColor ("_SunColor", sunLight.color);
58.         Vector3 lightDir = Vector3.Normalize (lightDirection);
59.         Shader.SetColor ("_LightDir", new Color (
60.             lightDir.x, lightDir.y, lightDir.z, 0));
61.        
62.         // HG Mie coefficients
63.         Shader.SetColor ("_GConst", new Color ((1-mistDirectionality) * (1-mistDirectionality), 1 + mistDirectionality* mistDirectionality, 2 * mistDirectionality,0));
64.     }
65.  
66.     // Update is called once per frame
67.     void LateUpdate () {
68.         CalculateConstants ();
69.     }
70.    
71.     void OnDrawGizmosSelected () {
72.         CalculateConstants ();
73.     }
74.     void OnDrawGizmos () {
75.         CalculateConstants ();
76.     }
77. }
78.  

This is much faster than calculating the stuff on every vertex or (gasp) every pixel.

 

wow a shaderlab impl of rayleigh mie scattering.. nicholas, can i, um, pleese have a look at this shader?

 

disregard my last post! lol, sry im a shader noob.. (thanks again for sharing your impl)