How to use dFdx() in SM3.0 GLSL?

dreamerflyer · Apr 4, 2012

Hi,i test the cg shader,below is some code ,but get error:

float2 duv = (sUV.x * dFdx (IN.uv.xy)) + (sUV.y * dFdy(IN.uv.xy));

Shader error in 'Custom/godRay': GLSL vertex shader: ERROR: 0:341: 'dFdx' : no matching overloaded function found at line 20

how to resolved it?

Martin-Kraus · Apr 4, 2012

I posted some GLSL code that works on my computer here: http://forum.unity3d.com/threads/130136-Misleading-shaderlab-documents

I assume it is a problem of your graphics hardware or driver not supporting this feature of GLSL.

dreamerflyer · Apr 4, 2012

Shader "Custom/godRay" {
Properties {
_MainTex ("Base (RGB)", 2D) = "white" {}
_BlurSpan("Blur span",Range (-12,12))=7
_Intensity("Intensity",Range(0,8))=4
_GlowGamma("Glow center",Range(0.5,3))=1.8
_BlurStart("Blur start",Range(-1,1))=1
_BlurWidth("Blur width",Range(-8,8))=-6
_gRepeat("Shink",Range(0.2,8))=4
_gFlipY("Flip Y?",Float)=0

}

SubShader {

Pass{
Tags { "RenderType"="Opaque" }
// LOD 200

CGPROGRAM
//#pragma exclude_renderers flash
#pragma vertex vert
#pragma fragment frag
#pragma target 3.0
#pragma profileoption NumTemps=64
#pragma glsl

#include "UnityCG.cginc"

sampler2D _MainTex;
float _BlurSpan;
float _Intensity;
float _GlowGamma;
float _BlurStart;
float _BlurWidth;
float _gRepeat;
float _gFlipY;

struct appdata {
float4 vertex : POSITION;
float2 texcoord : TEXCOORD0;
float4 normal : NORMAL0;
};

struct v2f {
float4 pos : SV_POSITION;
float4 uv : TEXCOORD0;
float4 ScreenCoords : TEXCOORD1; // we copy HPosition into this
};

v2f vert (appdata v)
{
v2f o;

float4 Po;
Po=v.vertex;
Po.w=1;

o.pos =o.ScreenCoords= mul (UNITY_MATRIX_MVP,Po);

float2 uvCenter=float2(0.5,0.5);

float2 nuv=v.texcoord-uvCenter;

if(_gFlipY==1)
{
nuv.y=-nuv.y;
}

nuv = float2(max(0.001,_gRepeat) * nuv.x,
max(0.001,_gRepeat) * nuv.y) + uvCenter;
o.uv = float4(nuv,0,0);
// o.color = v.normal * 0.5 + 0.5;
return o;
}

half4 frag (v2f IN) : COLOR
{
// half4 o=tex2D(_MainTex, IN.uv.xy);
float nsamples=32;
float2 sUV = float2(IN.ScreenCoords.x/IN.ScreenCoords.w,
IN.ScreenCoords.y/IN.ScreenCoords.w);
sUV = normalize(sUV);

//float2 duv = (sUV.x * dFdx (IN.uv.x)) + (sUV.y * dFdy(IN.uv.y));
float2 duv = (sUV.x * ddx (IN.uv.x)) + (sUV.y * ddy(IN.uv.y));

//float2 duv = (sUV.x * (IN.uv).x) + (sUV.y * (IN.uv).y);
duv *= _BlurSpan;

float4 blurred = 0;

for(int i=0; i<nsamples; i++) {
float scale = _BlurStart + _BlurWidth*(i/(float) (nsamples-1));
blurred += tex2Dlod(_MainTex,float4(IN.uv.xy+ scale * duv,0,0) );
}
blurred /= nsamples;
// tweak the color a bit
blurred.rgb = pow(blurred.rgb,_GlowGamma);
blurred.rgb *= _Intensity;
blurred.rgb = saturate(blurred.rgb);
// now composite original pic back on top of the blur
float4 origTex = tex2Dlod(_MainTex, IN.uv);
float3 newC = origTex.rgb + (1.0-origTex.a)*blurred.rgb;
float newA = max(origTex.a,blurred.a);
return float4(newC.rgb,newA);

}
ENDCG
}
}
FallBack "VertexLit"
}
Click to expand...

this is my code ,translate it from nvidia/s godRay.but not match the effect with the source code.

Martin-Kraus · Apr 4, 2012

Did you solve the problem with ddx and ddy?

Maybe you should start another thread about the problem of porting Nvidias god ray effect to unity?

dreamerflyer · Apr 4, 2012

aubergine · Apr 7, 2012

EDIT: Nevermind

dreamerflyer · Apr 7, 2012

Hi ,Aubergine,what's wrong with my codes?

aubergine · Apr 7, 2012

I posted this effect somewhere in the forums but now i decided to pull it off and put in a commercial pack instead.
Sorry.

dreamerflyer · Apr 7, 2012

then ,will other people help me?I want to port the NDIVIA 'S SHADERs to u3d,.

dreamerflyer · Apr 8, 2012

the codes almost as the NVIDIA'S .go on port other shader~

Search Unity

How to use dFdx() in SM3.0 GLSL?

dreamerflyer

Martin-Kraus

dreamerflyer

Martin-Kraus

dreamerflyer

Attached Files:

$nvidia-cg.png

$u3d-godRay.png

aubergine

dreamerflyer

aubergine

dreamerflyer

dreamerflyer

Search Unity

Unity ID

Useful Searches

How to use dFdx() in SM3.0 GLSL?

Attached Files: