// Copyright 2018 Google Inc.
precision mediump float;
uniform sampler2D u_MainTex;
uniform vec4 u_time;
uniform float u_EmissionGain;
varying vec4 v_color;
varying vec2 v_texcoord0;
vec4 GetRainbowColor( vec2 texcoord)
{
vec4 _Time = u_time;
texcoord = clamp(texcoord, 0.0, 1.0);
vec2 uvs = texcoord;
float row_id = floor(uvs.y * 5.0);
uvs.y *= 5.0;
vec4 tex = vec4(0.0,0.0,0.0,1.0);
float row_y = mod(uvs.y,1.0);
row_id = ceil(mod(row_id + _Time.z,5.0)) - 1.0;
tex.rgb = row_id == 0.0 ? vec3(1.0,0.0,0.0) : tex.rgb;
tex.rgb = row_id == 1.0 ? vec3(.7,.3,0.0) : tex.rgb;
tex.rgb = row_id == 2.0 ? vec3(0.0,1.0,.0) : tex.rgb;
tex.rgb = row_id == 3.0 ? vec3(0.0,.2,1.0) : tex.rgb;
tex.rgb = row_id == 4.0 ? vec3(.4,0.0,1.2) : tex.rgb;
tex.rgb *= pow( (sin(row_id * 1.0 + _Time.z) + 1.0)/2.0,5.0);
tex.rgb *= clamp(pow(row_y * (1.0 - row_y) * 5.0, 50.0), 0.0, 1.0);
return tex;
}
void main() {
vec4 color = v_color;
color.a = 1.;
vec4 tex = GetRainbowColor(v_texcoord0.xy);
tex = color * tex * exp(u_EmissionGain * 3.0);
gl_FragColor = tex * tex.a;
}