rhythmbullet/android/assets/shaders/star_frag.glsl

90 lines
2.2 KiB
GLSL
Executable File

// from https://www.shadertoy.com/view/Msf3Wr
#define GLSLSANDBOX
#ifdef GLSLSANDBOX
#ifdef GL_ES
precision mediump float;
#endif
uniform float time;
#ifndef GLSLSANDBOXTOYNOTCOMPATIBLE
uniform vec4 iMouse;
uniform int iFrame;
#else /*GLSLSANDBOXTOYNOTCOMPATIBLE*/
uniform vec2 mouse;
#define iMouse mouse
#endif /*GLSLSANDBOXTOYNOTCOMPATIBLE*/
uniform vec2 resolution;
#define iGlobalTime time
#define iResolution (vec3(resolution, 1.))
#endif /*GLSLSANDBOX*/
#define iterations 17
#define formuparam 0.53
#define volsteps 20
#define stepsize 0.1
#define zoom 0.800
#define tile 0.850
#define speed 0.010
#define brightness 0.0015
#define darkmatter 0.300
#define distfading 0.730
#define saturation 0.850
void mainImage( out vec4 fragColor, in vec2 fragCoord )
{
//get coords and direction
vec2 uv=fragCoord.xy/iResolution.xy-.5;
uv.y*=iResolution.y/iResolution.x;
vec3 dir=vec3(uv*zoom,1.);
float time=iGlobalTime*speed+.25;
float a1=.5+time/iResolution.x*2.;
float a2=.8+time/iResolution.y*2.;
mat2 rot1=mat2(cos(a1),sin(a1),-sin(a1),cos(a1));
mat2 rot2=mat2(cos(a2),sin(a2),-sin(a2),cos(a2));
dir.xz*=rot1;
dir.xy*=rot2;
vec3 from=vec3(1.,.5,0.5);
from+=vec3(time*2.,time,-2.);
from.xz*=rot1;
from.xy*=rot2;
//volumetric rendering
float s=0.1,fade=1.;
vec3 v=vec3(0.);
for (int r=0; r<volsteps; r++) {
vec3 p=from+s*dir*.5;
p = abs(vec3(tile)-mod(p,vec3(tile*2.))); // tiling fold
float pa,a=pa=0.;
for (int i=0; i<iterations; i++) {
p=abs(p)/dot(p,p)-formuparam; // the magic formula
a+=abs(length(p)-pa); // absolute sum of average change
pa=length(p);
}
float dm=max(0.,darkmatter-a*a*.001); //dark matter
a*=a*a; // add contrast
if (r>6) fade*=1.-dm; // dark matter, don't render near
//v+=vec3(dm,dm*.5,0.);
v+=fade;
v+=vec3(s,s*s,s*s*s*s)*a*brightness*fade; // coloring based on distance
fade*=distfading; // distance fading
s+=stepsize;
}
v=mix(vec3(length(v)),v,saturation); //color adjust
fragColor = vec4(v*.01,1.);
}
void main (void)
{
vec4 color = vec4 (0.0, 0.0, 0.0, 1.0);
mainImage (color, gl_FragCoord.xy);
color.w = 1.0;
gl_FragColor = color;
}