uniform sampler2DRect particles0;
uniform sampler2DRect particles1;
uniform sampler2DRect particles2;

uniform sampler2DRect   u_depth;
uniform sampler2DRect   u_world;
uniform sampler2DRect   u_v4l2cam;
uniform sampler2DRect   warm1;
uniform sampler2DRect   warm2;
uniform sampler2DRect   cold1;
uniform sampler2DRect   cold2;

uniform float uAreThereTwoPeopleTween;

uniform float u_time;

uniform vec3 uHottest0;
uniform vec3 uHottest1;
uniform vec3 uHottest3d0;
uniform vec3 uHottest3d1;
uniform vec3 uBetween;
uniform int uEnergy;

in vec2 texCoordVarying;
in vec3 gPos;
in vec4 gTarget;
in float gTemperature;
in float gAge;


vec3 random3(vec3 c) {
	float j = 4096.0*sin(dot(c,vec3(17.0, 59.4, 15.0)));
	vec3 r;
	r.z = fract(512.0*j);
	j *= .125;
	r.x = fract(512.0*j);
	j *= .125;
	r.y = fract(512.0*j);
	return r-0.5;
}

/* skew constants for 3d simplex functions */
const float F3 =  0.3333333;
const float G3 =  0.1666667;

/* 3d simplex noise */
float simplex3d(vec3 p) {
	 /* 1. find current tetrahedron T and it's four vertices */
	 /* s, s+i1, s+i2, s+1.0 - absolute skewed (integer) coordinates of T vertices */
	 /* x, x1, x2, x3 - unskewed coordinates of p relative to each of T vertices*/
	 
	 /* calculate s and x */
	 vec3 s = floor(p + dot(p, vec3(F3)));
	 vec3 x = p - s + dot(s, vec3(G3));
	 
	 /* calculate i1 and i2 */
	 vec3 e = step(vec3(0.0), x - x.yzx);
	 vec3 i1 = e*(1.0 - e.zxy);
	 vec3 i2 = 1.0 - e.zxy*(1.0 - e);
	 	
	 /* x1, x2, x3 */
	 vec3 x1 = x - i1 + G3;
	 vec3 x2 = x - i2 + 2.0*G3;
	 vec3 x3 = x - 1.0 + 3.0*G3;
	 
	 /* 2. find four surflets and store them in d */
	 vec4 w, d;
	 
	 /* calculate surflet weights */
	 w.x = dot(x, x);
	 w.y = dot(x1, x1);
	 w.z = dot(x2, x2);
	 w.w = dot(x3, x3);
	 
	 /* w fades from 0.6 at the center of the surflet to 0.0 at the margin */
	 w = max(0.6 - w, 0.0);
	 
	 /* calculate surflet components */
	 d.x = dot(random3(s), x);
	 d.y = dot(random3(s + i1), x1);
	 d.z = dot(random3(s + i2), x2);
	 d.w = dot(random3(s + 1.0), x3);
	 
	 /* multiply d by w^4 */
	 w *= w;
	 w *= w;
	 d *= w;
	 
	 /* 3. return the sum of the four surflets */
	 return dot(d, vec4(52.0));
}

/* const matrices for 3d rotation */
const mat3 rot1 = mat3(-0.37, 0.36, 0.85,-0.14,-0.93, 0.34,0.92, 0.01,0.4);
const mat3 rot2 = mat3(-0.55,-0.39, 0.74, 0.33,-0.91,-0.24,0.77, 0.12,0.63);
const mat3 rot3 = mat3(-0.71, 0.52,-0.47,-0.08,-0.72,-0.68,-0.7,-0.45,0.56);

/* directional artifacts can be reduced by rotating each octave */
float simplex3d_fractal(vec3 m) {
    return   0.5333333*simplex3d(m*rot1)
			+0.2666667*simplex3d(2.0*m*rot2)
			+0.1333333*simplex3d(4.0*m*rot3)
			+0.0666667*simplex3d(8.0*m);
}

void main()
{
  if(gAge >= 1) discard;
  vec2 palette = vec2(gTemperature*3425, 0.5);
  vec3 remapedColorW = texture(warm1, palette).xyz;
  vec3 remapedColorC = texture(cold2, palette).xyz;
  float d = 80;
  float D = 600;
  float n = (simplex3d(gPos * vec3(0.01, 0.01, 0.1 * sin(u_time * 0.01)))) * 100;
  float rate = 1-smoothstep(D - d, D + d, length(gPos.x + uBetween.x) + n);
  rate *= uAreThereTwoPeopleTween;
  vec3 remapedColor = mix(remapedColorC, remapedColorW, rate);
  float alpha = min(1, max(0, 1 - pow(gAge,4)));
  if(uEnergy > 0) {
    alpha *= 0.05;
  }
  else {
    alpha *= 0.1;
  }

  if(gPos.z > -200) {
    discard;
  }
  vec4 color = vec4(remapedColor, alpha);

  fragColor = color;
}