#ifdef GL_ES
precision mediump float;
#endif

const vec3 background = vec3(1.0);
const vec3 primary = vec3(0., 0.345, 0.761);
const vec3 tertiary = vec3(1., 0., 0.);

varying float vHeight;
varying float vColor;

void main() {
  float height = vHeight * 2.0 + 0.9;

  vec3 color = mix(primary, tertiary, vColor * 3.0 + 0.5);

  gl_FragColor = vec4(mix(color, background, height), 1.0);
}