uniform float tsec, phase;

float cnoise(vec2 p);
float fbm(vec2 p, int octaves);

void main()
{
	const vec3 color = vec3(0.2, 0.4, 1.0);

	float tm = tsec + phase;

	vec2 uv = gl_TexCoord[0].st;
	vec2 pt = uv * vec2(2.0) - vec2(1.0);

	float pulse = fbm(vec2(uv.y * 50.0 - tm * 0.5, 0.0), 2);

	float d_horiz = abs(pt.x);
	float d_vert = max(abs(pt.y), 0.0);

	float beam_sharpness = 80.0 * clamp(pow(uv.y, 0.5), 0.0, 1.0) * (pulse * 0.5 + 1.0);
	float beam_intensity = 6.0 * min(0.01 / (uv.y * uv.y) - 0.0004, 1.0);

	float glow_u = pow(1.0 - smoothstep(0.0, 1.0, d_horiz), beam_sharpness) * beam_intensity;
	float glow_v = 1.0 - smoothstep(0.98, 1.0, d_vert);

	float glow = glow_u * glow_v;

	gl_FragColor.rgb = color * glow;// + vec3(0.0, 1.0, 0.0) * step(0.99, max(abs(pt.x), abs(pt.y)));
	gl_FragColor.a = 1.0;
}

float fbm(vec2 p, int octaves)
{
	float res = 0.0;
	float freq = 1.0;
	float scale = 1.0;

	for(int i=0; i<octaves; i++) {
		res += cnoise(p * freq) * scale;
		freq *= 2.0;
		scale *= 0.5;
	}
	return res;
}

//
// GLSL textureless classic 2D noise "cnoise",
// with an RSL-style periodic variant "pnoise".
// Author:  Stefan Gustavson (stefan.gustavson@liu.se)
// Version: 2011-08-22
//
// Many thanks to Ian McEwan of Ashima Arts for the
// ideas for permutation and gradient selection.
//
// Copyright (c) 2011 Stefan Gustavson. All rights reserved.
// Distributed under the MIT license. See LICENSE file.
// https://github.com/stegu/webgl-noise
//

vec4 mod289(vec4 x)
{
  return x - floor(x * (1.0 / 289.0)) * 289.0;
}

vec4 permute(vec4 x)
{
  return mod289(((x*34.0)+1.0)*x);
}

vec4 taylor_inv_sqrt(vec4 r)
{
  return 1.79284291400159 - 0.85373472095314 * r;
}

vec2 fade(vec2 t) {
  return t*t*t*(t*(t*6.0-15.0)+10.0);
}

// Classic perlin noise
float cnoise(vec2 p)
{
  vec4 pi = floor(p.xyxy) + vec4(0.0, 0.0, 1.0, 1.0);
  vec4 pf = fract(p.xyxy) - vec4(0.0, 0.0, 1.0, 1.0);
  pi = mod289(pi); // To avoid truncation effects in permutation
  vec4 ix = pi.xzxz;
  vec4 iy = pi.yyww;
  vec4 fx = pf.xzxz;
  vec4 fy = pf.yyww;

  vec4 i = permute(permute(ix) + iy);

  vec4 gx = fract(i * (1.0 / 41.0)) * 2.0 - 1.0 ;
  vec4 gy = abs(gx) - 0.5 ;
  vec4 tx = floor(gx + 0.5);
  gx = gx - tx;

  vec2 g00 = vec2(gx.x,gy.x);
  vec2 g10 = vec2(gx.y,gy.y);
  vec2 g01 = vec2(gx.z,gy.z);
  vec2 g11 = vec2(gx.w,gy.w);

  vec4 norm = taylor_inv_sqrt(vec4(dot(g00, g00), dot(g01, g01), dot(g10, g10), dot(g11, g11)));
  g00 *= norm.x;  
  g01 *= norm.y;  
  g10 *= norm.z;  
  g11 *= norm.w;  

  float n00 = dot(g00, vec2(fx.x, fy.x));
  float n10 = dot(g10, vec2(fx.y, fy.y));
  float n01 = dot(g01, vec2(fx.z, fy.z));
  float n11 = dot(g11, vec2(fx.w, fy.w));

  vec2 fade_xy = fade(pf.xy);
  vec2 n_x = mix(vec2(n00, n01), vec2(n10, n11), fade_xy.x);
  float n_xy = mix(n_x.x, n_x.y, fade_xy.y);
  return 2.3 * n_xy;
}