// 2D plasma in C64 graphics style
//
// Version 1.0 (2013-03-31)
// Simon Stelling-de San Antonio

#version 130

uniform float iTime;

void main()
{
    float camtime = 1.23*iTime;
	vec2 iResolution = vec2(1280, 720);
	vec4 fragCoord = gl_FragCoord;
	
    vec2 p = fragCoord.xy / iResolution.xy;
    p.y = 1.0 - p.y;
    p *= 200.0;
    p.x *= (iResolution.x / iResolution.y);
    p.x /= 2.0;
    p = floor(p);
    p.x *= 2.0;
    float a = p.x+30.0*sin(p.x/21.0 + 0.3*sin(0.4*camtime))+20.0*cos(p.y/19.0 + 0.2*cos(0.6*camtime))-160.0;
    float b = p.y+30.0*cos(p.y/18.0 + 0.4*sin(0.7*camtime))+20.0*sin(p.x/16.0 + 0.5*cos(0.7*camtime))- 97.0;
    float e = floor((length(vec2(a,b))
              +4.0*mod(floor((p.x+p.y+p.y)/2.0),2.0))/13.0);
    float c;
    if        (e ==  0.0) { c =  9.0;
    } else if (e ==  1.0) { c =  2.0;
    } else if (e ==  2.0) { c =  8.0;
    } else if (e ==  3.0) { c = 10.0;
    } else if (e ==  4.0) { c = 15.0;
    } else if (e ==  5.0) { c =  7.0;
    } else if (e ==  6.0) { c =  1.0;
    } else if (e ==  7.0) { c = 13.0;
    } else if (e ==  8.0) { c =  3.0;
    } else if (e ==  9.0) { c = 14.0;
    } else if (e == 10.0) { c =  4.0;
    } else if (e == 11.0) { c =  6.0;
    } else if (e == 12.0) { c =  0.0;
    } else if (e == 13.0) { c = 11.0;
    } else if (e == 14.0) { c =  5.0;
    } else                { c = 12.0;
    }
    vec3 col;
    if        (c ==  0.0) { col = vec3(0.0);
    } else if (c ==  1.0) { col = vec3(0.0);
    } else if (c ==  2.0) { col = vec3(137.0,  64.0,  54.0)/256.0;
    } else if (c ==  3.0) { col = vec3(122.0, 191.0, 199.0)/256.0;
    } else if (c ==  4.0) { col = vec3(138.0,  70.0, 174.0)/256.0;
    } else if (c ==  5.0) { col = vec3(104.0, 169.0,  65.0)/256.0;
    } else if (c ==  6.0) { col = vec3( 62.0,  49.0, 162.0)/256.0;
    } else if (c ==  7.0) { col = vec3(208.0, 220.0, 113.0)/256.0;
    } else if (c ==  8.0) { col = vec3(144.0,  95.0,  37.0)/256.0;
    } else if (c ==  9.0) { col = vec3( 92.0,  71.0,   0.0)/256.0;
    } else if (c == 10.0) { col = vec3(187.0, 119.0, 109.0)/256.0;
    } else if (c == 11.0) { col = vec3( 85.0,  85.0,  85.0)/256.0;
    } else if (c == 12.0) { col = vec3(128.0, 128.0, 128.0)/256.0;
    } else if (c == 13.0) { col = vec3(172.0, 234.0, 136.0)/256.0;
    } else if (c == 14.0) { col = vec3(124.0, 112.0, 218.0)/256.0;
    } else                { col = vec3(171.0, 171.0, 171.0)/256.0;
    }
    
	gl_FragColor = vec4(col,1.0);
}
