// Copyright (c) 2017-2018 Xiamen Yaji Software Co., Ltd.

CCEffect %{
  techniques:
  - passes:
    - vert: vs
      frag: fs
      blendState:
        targets:
        - blend: true
      rasterizerState:
        cullMode: none
      properties:
        texture: { value: white }
        texture2: { value: white }
        time: { value: 0 }
        direction: { value: [1, 1]}
}%

CCProgram transition %{

// https://www.shadertoy.com/view/ls3cDB

const float PI = 3.141592653589793;
const float PI_2 = 3.141592653589793;

#define radius .1

uniform Transition {
  vec2 direction; // = [1, 1]
};

float aspect = 1.;//screenSize.x / screenSize.y;

vec4 iMouse = vec4(
  screenSize.x * (mod((1.0 + time * direction.x), 1.0) + 0.2 * sign(direction.x)),
  screenSize.y * (mod((1.0 + time * direction.y), 1.0) + 0.2 * sign(direction.y)),
  screenSize.x * (1.0 - step(0.0, direction.x)),
  screenSize.y * (1.0 - step(0.0, direction.y))
);


vec2 mouse = iMouse.xy  * vec2(aspect, 1.) / screenSize.xy;
vec2 mouseDir = normalize(abs(iMouse.zw) - iMouse.xy);

vec4 transition(vec2 uv) {
  // vec2 uv = fragCoord * vec2(aspect, 1.) / screenSize.xy;

  float dist = dot(uv - mouse, mouseDir);
  vec2 linePoint = uv - dist * mouseDir;

  vec4 fragColor = vec4(1.0);
  if (dist > radius)  {
    fragColor = texture(texture2, uv);
    // add shadow
    // fragColor.rgb *= pow(clamp(dist - radius, 0., 1.) * 1.5, .2);
  }
  else if (dist >= 0.) {
    // map to cylinder point
    float theta = asin(dist / radius);
    vec2 p2 = linePoint + mouseDir * (PI - theta) * radius;
    vec2 p1 = linePoint + mouseDir * theta * radius;
    uv = (p2.x <= aspect && p2.y <= 1. && p2.x > 0. && p2.y > 0.) ? p2 : p1;
    fragColor = texture(texture, uv);
    fragColor.rgb *= pow(clamp((radius - dist) / radius, 0., 1.), .2);
  }
  else  {
    vec2 p = linePoint + mouseDir * (abs(dist) + PI * radius);
    uv = (p.x <= aspect && p.y <= 1. && p.x > 0. && p.y > 0.) ? p : uv;
    fragColor = texture(texture, uv);
  }

  return fragColor;
}

}%

CCProgram vs %{

precision highp float;

#include <cc-global>
#include <cc-local>

in vec3 a_position;
in lowp vec4 a_color;

in mediump vec2 a_uv0;
out mediump vec2 v_uv0;

out lowp vec4 v_color;

uniform Time {
  vec2 screenSize;
  float time;
};

void main() {
  mat4 mvp;

  mvp = cc_matViewProj;

  v_uv0 = a_uv0;
  v_color = a_color;

  gl_Position = mvp * vec4(a_position, 1);
}

}%

CCProgram fs %{

precision highp float;

uniform sampler2D texture;
uniform sampler2D texture2;
in mediump vec2 v_uv0;

uniform Time {
  vec2 screenSize;
  float time;
};

in lowp vec4 v_color;

vec4 getFromColor(vec2 uv) {
  return texture(texture, uv);
}

vec4 getToColor(vec2 uv) {
  return texture(texture2, uv);
}

#include <transition>

void main () {
  gl_FragColor = v_color * transition(v_uv0);
}

}%