So, I found this shader on the forums that PRD wrote a little while back and I’m unsure how to add transparency to this shader. I’m not very experienced with shaders, I can write some simple surface shaders but I don’t know how to go about adding transparency to this one in particular. Basically I want to be able to see the stars and such from the surface of my planet instead of a black sky at night (and my planet’s moon at day as well). Here’s the shader:
Shader "Atmosphere/SkyFromAtmosphere"
{
SubShader
{
Tags { "RenderType"="Transparent" }
Pass
{
Cull Front
CGPROGRAM
#include "UnityCG.cginc"
#pragma target 3.0
#pragma vertex vert
#pragma fragment frag
uniform float3 v3LightPos; // The direction vector to the light source
uniform float3 v3InvWavelength; // 1 / pow(wavelength, 4) for the red, green, and blue channels
uniform float fOuterRadius; // The outer (atmosphere) radius
uniform float fOuterRadius2; // fOuterRadius^2
uniform float fInnerRadius; // The inner (planetary) radius
uniform float fInnerRadius2; // fInnerRadius^2
uniform float fKrESun; // Kr * ESun
uniform float fKmESun; // Km * ESun
uniform float fKr4PI; // Kr * 4 * PI
uniform float fKm4PI; // Km * 4 * PI
uniform float fScale; // 1 / (fOuterRadius - fInnerRadius)
uniform float fScaleDepth; // The scale depth (i.e. the altitude at which the atmosphere's average density is found)
uniform float fScaleOverScaleDepth; // fScale / fScaleDepth
uniform float fHdrExposure; // HDR exposure
uniform float g; // The Mie phase asymmetry factor
uniform float g2; // The Mie phase asymmetry factor squared
struct v2f
{
float4 pos : SV_POSITION;
float2 uv : TEXCOORD0;
float3 t0 : TEXCOORD1;
float3 c0 : COLOR0;
float3 c1 : COLOR1;
};
float scale(float fCos)
{
float x = 1.0 - fCos;
return 0.25 * exp(-0.00287 + x*(0.459 + x*(3.83 + x*(-6.80 + x*5.25))));
}
v2f vert(appdata_base v)
{
float3 v3CameraPos = _WorldSpaceCameraPos; // The camera's current position
float fCameraHeight = length(v3CameraPos); // The camera's current height
//float fCameraHeight2 = fCameraHeight*fCameraHeight; // fCameraHeight^2
// Get the ray from the camera to the vertex and its length (which is the far point of the ray passing through the atmosphere)
float3 v3Pos = mul(_Object2World, v.vertex).xyz;
float3 v3Ray = v3Pos - v3CameraPos;
float fFar = length(v3Ray);
v3Ray /= fFar;
// Calculate the ray's starting position, then calculate its scattering offset
float3 v3Start = v3CameraPos;
float fHeight = length(v3Start);
float fDepth = exp(fScaleOverScaleDepth * (fInnerRadius - fCameraHeight));
float fStartAngle = dot(v3Ray, v3Start) / fHeight;
float fStartOffset = fDepth*scale(fStartAngle);
const float fSamples = 2.0;
// Initialize the scattering loop variables
float fSampleLength = fFar / fSamples;
float fScaledLength = fSampleLength * fScale;
float3 v3SampleRay = v3Ray * fSampleLength;
float3 v3SamplePoint = v3Start + v3SampleRay * 0.5;
// Now loop through the sample rays
float3 v3FrontColor = float3(0.0, 0.0, 0.0);
for(int i=0; i<int(fSamples); i++)
{
float fHeight = length(v3SamplePoint);
float fDepth = exp(fScaleOverScaleDepth * (fInnerRadius - fHeight));
float fLightAngle = dot(v3LightPos, v3SamplePoint) / fHeight;
float fCameraAngle = dot(v3Ray, v3SamplePoint) / fHeight;
float fScatter = (fStartOffset + fDepth*(scale(fLightAngle) - scale(fCameraAngle)));
float3 v3Attenuate = exp(-fScatter * (v3InvWavelength * fKr4PI + fKm4PI));
v3FrontColor += v3Attenuate * (fDepth * fScaledLength);
v3SamplePoint += v3SampleRay;
}
v2f OUT;
OUT.pos = mul(UNITY_MATRIX_MVP, v.vertex);
OUT.uv = v.texcoord.xy;
// Finally, scale the Mie and Rayleigh colors and set up the varying variables for the pixel shader
OUT.c0 = v3FrontColor * (v3InvWavelength * fKrESun);
OUT.c1 = v3FrontColor * fKmESun;
OUT.t0 = v3CameraPos - v3Pos;
return OUT;
}
// Calculates the Mie phase function
float getMiePhase(float fCos, float fCos2, float g, float g2)
{
return 1.5 * ((1.0 - g2) / (2.0 + g2)) * (1.0 + fCos2) / pow(1.0 + g2 - 2.0*g*fCos, 1.5);
}
// Calculates the Rayleigh phase function
float getRayleighPhase(float fCos2)
{
return 0.75 + 0.75*fCos2;
}
half4 frag(v2f IN) : COLOR
{
float fCos = dot(v3LightPos, IN.t0) / length(IN.t0);
float fCos2 = fCos*fCos;
float3 col = getRayleighPhase(fCos2) * IN.c0 + getMiePhase(fCos, fCos2, g, g2) * IN.c1;
//Adjust color from HDR
col = 1.0 - exp(col * -fHdrExposure);
return float4(col,1.0);
}
ENDCG
}
}
}
The best I could do was change the render type, but yeah I don’t know how to do this, atm if you look up in the sky you see all of the atmospheric scattering at work but nothing beyond the atmosphere.