이번 목표로 설정! (이미 열흘전에 정한거지만..) http://glsl.herokuapp.com/e#13456.1

img
#ifdef GL_ES
precision mediump float;
#endif

#define STEPS 80
#define LIGHTPASSES 2
uniform float time;
uniform vec2 mouse;
uniform vec2 resolution;

vec2 c = vec2(0.5,0.5*resolution.y/resolution.x);
vec3 wallColor = vec3(1.,1.,1.);

/*by Olivier de Schaetzen (citiral)
haven't really seen anything like this before, so either I don't check enough shaders or I might have made something original once ;)
*/

//random function not by me, found it somewhere on the internet!
float rand(vec2 n)
{
  return 1. * 
     fract(sin(dot(n.xy, vec2(12.9898, 78.233)))* 43758.5453);
}

vec3 getColor(vec2 p)
{   
    if (p.x >= 0.1 && p.x <= 0.19 && p.y >= 0.1 && p.y <= 0.19) {
        return wallColor;
    }

    p.x += sin(time)*0.1;
    p.y += cos(time)*0.1;
    if (length(p-c) <= 0.05) {
        return wallColor;   
    }

    return vec3(0.3,0.3,0.3);
}

vec3 getLighting(vec2 p, vec2 lp)
{
    vec2 sp = p;
    vec2 v = (lp-p)/float(STEPS);

    for (int i = 0 ; i < STEPS ; i++) {
        if (getColor(sp) == wallColor) {
            return length(p-lp)/vec3(1.,1.,1.) + 1./length(p-lp)*0.075*vec3(1.0,0.5*(sin(time)+1.),0.6);
        }
        sp += v;
    }

    return vec3(1.0,1.0,1.0)+1./length(p-lp)*0.075*vec3(1.0,0.5*(sin(time)+1.),0.6);
}

vec3 blendLighting(vec2 p, vec2 lp)
{   
    vec2 r;
    vec3 c = vec3(0.,0.,0.);

    for (int i = 1 ; i <= LIGHTPASSES ; i++) {
        r = vec2(rand(sin(time*float(i))+p.xy)*0.03-0.015,rand(cos(time*float(i))+p.yx)*0.03-0.015);
        c += getLighting(p,lp+r)/float(LIGHTPASSES);
    }

    return c;
}

void main( void ) {

    vec2 p = gl_FragCoord.xy/resolution.xy;
    vec2 lp = mouse.xy;
    p.y *= resolution.y/resolution.x;
    lp.y *= resolution.y/resolution.x;  

    gl_FragColor = vec4(getColor(p)*blendLighting(p,lp),1.);
}