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2 years ago
//Star Nest algorithm by Pablo Román Andrioli
//Unity 5.x shader by Jonathan Cohen
//This content is under the MIT License.
//
//Original Shader:
//https://www.shadertoy.com/view/XlfGRj
//
//This shader uses the same algorithm in 3d space to render a skybox.
Shader "FX/Galaxy" {
Properties {
_MainTex ("Texture Sampler (UV Only)", 2D) = "grey" {}
//2D: Zoom level
_Zoom ("Zoom", Float) = 800
_Color ("Main Color", Color) = (1,1,1,1)
[Toggle(CLAMPOUT)] _CLAMPOUT("Clamp Output with Main Color", Float) = 0
//Scrolls in this direction over time. Set 'w' to zero to stop scrolling.
_Scroll ("Scrolling direction (x,y,z) * w * time", Vector) = (3, 1, .6, .01)
//Center position in space and time.
_Center ("Center Position (x, y, z, time)", Vector) = (1, .3, .5, 0)
//Rotation angles
_Rotation ("Rotation (x,y,z)*w angles", Vector) = (35, 25, 75, .1)
//Iterations of inner loop.
//The higher this is, the more distant objects get rendered.
_Iterations ("Iterations", Range(1, 30)) = 17
//Volumetric rendering steps. Each 'step' renders more objects at all distances.
//This has a higher performance hit than iterations.
_Volsteps ("Volumetric Steps", Range(1,40)) = 20
//Magic number. Best values are around 400-600.
_Formuparam ("Formuparam", Float) = 530
//How much farther each volumestep goes
_StepSize ("Step Size", Float) = 130
//Fractal repeating rate
//Low numbers are busy and give lots of repititio
//High numbers are very sparce
_Tile ("Tile", Float) = 700
//Brightness scale.
_Brightness ("Brightness", Float) = 2
//Abundance of Dark matter (in the distance).
//Visible with Volsteps >= 8 (at 7 its really, really hard to see)
_Darkmatter ("Dark Matter", Float) = 25
//Brightness of distant objects (or dim) are distant objects
//Ironically, Also affets brightness of 'darkmatter'
_Distfading ("Distance Fading", Float) = 68
//How much color is present?
_Saturation ("Saturation", Float) = 85
}
SubShader {
Tags { "Queue"="Geometry" "RenderType"="Opaque" }
Cull Off
CGPROGRAM
#pragma surface surf Lambert
#pragma multi_compile __ CLAMPOUT
#include "UnityCG.cginc"
fixed4 _Color;
int _Volsteps;
int _Iterations;
sampler2D _MainTex;
float4 _Scroll;
float4 _Center;
float _CamScroll;
float4 _Rotation;
float _Formuparam;
float _StepSize;
float _Zoom;
float _Tile;
float _Brightness;
float _Darkmatter;
float _Distfading;
float _Saturation;
struct Input {
float2 uv_MainTex;
};
void surf (Input IN, inout SurfaceOutput o) {
half3 col = half3(0, 0, 0);
float zoom = _Zoom / 1000;
float2 uv = IN.uv_MainTex;
uv -= .5;
half3 dir = float3(uv * zoom, 1);
float time = _Center.w + _Time.x;
//Un-scale parameters (source parameters for these are mostly in 0...1 range)
//Scaling them up makes it much easier to fine-tune shader in the inspector.
float brightness = _Brightness / 1000;
float stepSize = _StepSize / 1000;
float3 tile = abs(float3(_Tile, _Tile, _Tile)) / 1000;
float formparam = _Formuparam / 1000;
float darkmatter = _Darkmatter / 100;
float distFade = _Distfading / 100;
float3 from = _Center.xyz;
//scroll over time
from += _Scroll.xyz * _Scroll.w * time;
//scroll from camera position
//from += _WorldSpaceCameraPos * _CamScroll * .00001;
//Apply rotation if enabled
float3 rot = _Rotation.xyz * _Rotation.w;
if (length(rot) > 0) {
float2x2 rx = float2x2(cos(rot.x), sin(rot.x), -sin(rot.x), cos(rot.x));
float2x2 ry = float2x2(cos(rot.y), sin(rot.y), -sin(rot.y), cos(rot.y));
float2x2 rz = float2x2(cos(rot.z), sin(rot.z), -sin(rot.z), cos(rot.z));
dir.xy = mul(rz, dir.xy);
dir.xz = mul(ry, dir.xz);
dir.yz = mul(rx, dir.yz);
from.xy = mul(rz, from.xy);
from.xz = mul(ry, from.xz);
from.yz = mul(rx, from.yz);
}
//volumetric rendering
float s = 0.1, fade = 1.0;
float3 v = float3(0, 0, 0);
for (int r = 0; r < _Volsteps; r++) {
float3 p = abs(from + s * dir * .5);
p = abs(float3(tile - fmod(p, tile*2)));
float pa,a = pa = 0.;
for (int i = 0; i < _Iterations; i++) {
p = abs(p) / dot(p, p) - formparam;
a += abs(length(p) - pa);
pa = length(p);
}
//Dark matter
float dm = max(0., darkmatter - a * a * .001);
if (r > 6) { fade *= 1. - dm; } // Render distant darkmatter
a *= a * a; //add contrast
v += fade;
// coloring based on distance
v += float3(s, s*s, s*s*s*s) * a * brightness * fade;
// distance fading
fade *= distFade;
s += stepSize;
}
float len = length(v);
//Quick color saturate
v = lerp(float3(len, len, len), v, _Saturation / 100);
v.xyz *= _Color.xyz * .01;
#ifdef CLAMPOUT
v = clamp(v, float3(0,0,0), _Color.xyz);
#endif
o.Emission = float3(v * .01);
}
ENDCG
}
Fallback Off
}