CMH Studio


#ifdef GL_ES
precision mediump float;
#define GLSLIFY 1
#endif

uniform vec2 u_resolution;
uniform float u_time;
uniform vec2 u_mouse;

#define GLSLIFY 1
vec2 hash2( vec2 x )        //亂數範圍 [-1,1]
{
    const vec2 k = vec2( 0.3183099, 0.3678794 );
    x = x*k + k.yx;
    return -1.0 + 2.0*fract( 16.0 * k*fract( x.x*x.y*(x.x+x.y)) );
}

float gnoise( in vec2 p )   //亂數範圍 [-1,1]
{
    vec2 i = floor( p );
    vec2 f = fract( p );
    
    vec2 u = f*f*(3.0-2.0*f);

    return mix( mix( dot( hash2( i + vec2(0.0,0.0) ), f - vec2(0.0,0.0) ), 
        dot( hash2( i + vec2(1.0,0.0) ), f - vec2(1.0,0.0) ), u.x),
        mix( dot( hash2( i + vec2(0.0,1.0) ), f - vec2(0.0,1.0) ), 
        dot( hash2( i + vec2(1.0,1.0) ), f - vec2(1.0,1.0) ), u.x), u.y);
}

float fbm(in vec2 uv)       //亂數範圍 [-1,1]
{
    float f;                //fbm - fractal noise (4 octaves)
    mat2 m = mat2( 1.6,  1.2, -1.2,  1.6 );
    f   = 0.5000*gnoise( uv ); 
    uv = m*uv;		  
    f += 0.2500*gnoise( uv ); 
    uv = m*uv;
    f += 0.1250*gnoise( uv ); 
    uv = m*uv;
    f += 0.0625*gnoise( uv ); 
    uv = m*uv;
    return f;
}

float glow(float d, float str, float thickness){
    return thickness / pow(d, str);
}

void main(){
    vec2 uv = gl_FragCoord.xy/u_resolution.xy;
    // uv.x *= u_resolution.x/u_resolution.y;
    uv= uv*2.0-1.0;
    //陰晴圓缺
    float pi=3.14159;
    float theta=2.0*pi*u_time/8.0;
    vec2 point=vec2(sin(theta), cos(theta));
    float dir= dot(point, (uv))+0.55;
    
    //亂數作用雲霧
    float fog= fbm(0.4*uv+vec2(-0.1*u_time, -0.02*u_time))*0.6+0.1;

    //定義圓環
    float dist = length(uv);
    float circle_dist = abs(dist-0.512);//光環大小
    
    //動態呼吸
    float breathing=sin(2.0*u_time/5.0*pi)*0.5+0.2;//option1
    //float breathing=(exp(sin(u_time/2.0*pi)) - 0.36787944)
        //*0.42545906412;//option2 錯誤
    //float breathing=(exp(sin(u_time/2.0*pi)) - 0.36787944)
        //*0.42545906412;//option2 正確
    float strength =(0.2*breathing+0.180);  
    //[0.2~0.3] //光暈強度加上動態時間營造呼吸感

    float thickness=(0.1*breathing+0.084);  
    //[0.1~0.2] //光環厚度 營造呼吸感

    float glow_circle = glow(circle_dist, strength, thickness);

    gl_FragColor = vec4((vec3(glow_circle)+fog)
        *dir*vec3(1.0, 0.5, 0.25),1.0);
    // return vec3(((glow_circle)+fog)
    //     *dir*vec3(1.0, 0.5, 0.25));
}
Breathing Glow
