30-days-of-shade/assets/shaders/023_tri_buffer.frag at master · willstall/30-days-of-shade · GitHub

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/*

    daily: 023
    author: Will Stallwood
    insta: https://www.instagram.com/willstall/

*/

#ifdef GL_ES
    precision mediump float;
#endif

#define PI 3.14159265359
#define HALF_PI 1.57079632675
#define TWO_PI 6.283185307

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

uniform sampler2D u_buffer0;
uniform sampler2D u_buffer1;

float sdEquilateralTriangle( in vec2 p )
{
    float k = sqrt(3.0);

    p.x = abs(p.x) - 1.0;
    p.y = p.y + 1.0/k;
    if( p.x + k*p.y > 0.0 ) p = vec2( p.x - k*p.y, -k*p.x - p.y )/2.0;
    p.x -= clamp( p.x, -2.0, 0.0 );
    return -length(p)*sign(p.y);
}

mat2 rotate(float angle)
{
    return mat2( cos(angle),-sin(angle),sin(angle),cos(angle) );
}

vec2 center(vec2 st)
{
    float aspect = u_resolution.x/u_resolution.y;
    st.x = st.x * aspect - aspect * 0.5 + 0.5;
    return st;
}

 void main()
 {
    // timing, if using cos+sin times are doubled
    float seconds = 5.0;
    float t = fract(u_time/seconds);

    // space
    vec2 st = gl_FragCoord.xy / u_resolution.xy;
    // st = center( st );

    // vars
    vec3 buffer,color;
    vec3 sdf = vec3( 1.0 );

    #if defined( BUFFER_0 )
        st = center( st );
        buffer = texture2D(u_buffer1, st).rgb;

        vec2 pos = vec2(0.5);
            pos.x += .3 * sin(TWO_PI*t);
            pos.y += .13 * cos(TWO_PI*t);

        // sdf.x = length(st-pos)-0.05;
        // sdf.x = 1.0 - smoothstep(0.0,0.001,sdf.x);

        st -= 0.5;
        st *= rotate(TWO_PI*t*3.0);
        st += 0.5;

        float base = .3 + .6 * sin(TWO_PI*3.0*t);
        sdf.y = sdEquilateralTriangle((st-pos)/base)*base;
        sdf.y = abs(sdf.y+.03)-.001;
        sdf.y = 1.0 - smoothstep(0.0,0.003,sdf.y);

        color = vec3(sdf);
        gl_FragColor = vec4(color, 1.0);

    #elif defined( BUFFER_1 )
        vec3 buffer_1 = texture2D(u_buffer1, st).rgb;
        buffer = texture2D(u_buffer0, st).rgb;
        // buffer *= 0.999999;
        // color = mix(buffer_1,buffer,buffer*.003);
        float f = mod(u_fps,60.0);

        color = mix(buffer,buffer_1,
            (1.0-buffer)*.9);

        // color = vec3((1.0/u_fps));
        // (1.0-buffer)*4000000.9999999);
            // (1.0-buffer)*(1.0-mod(u_time,.075)* (1.0-mod(u_fps,60.0)) ));
        gl_FragColor = vec4(color, 1.0);
    #else
        // st = center( st );
        buffer = texture2D(u_buffer1, st).rgb;

        color = vec3(0.07);
        color = mix(color,vec3(1.0),buffer.y);
        // color = vec3(length(buffer));
        // color = mix(color,buffer,0.3);
        gl_FragColor = vec4(color, 1.0);
    #endif
}