isf 0.1.0

Parsing, Deserialization and Serialization of the Interactive Shader Format.
Documentation 
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/*{
    "CATEGORIES": [
        "Wipe"
    ],
    "CREDIT": "Automatically converted from https://www.github.com/gl-transitions/gl-transitions/tree/master/angular.glsl",
    "DESCRIPTION": "",
    "INPUTS": [
        {
            "NAME": "startImage",
            "TYPE": "image"
        },
        {
            "NAME": "endImage",
            "TYPE": "image"
        },
        {
            "DEFAULT": 0,
            "MAX": 1,
            "MIN": 0,
            "NAME": "progress",
            "TYPE": "float"
        },
        {
            "DEFAULT": 90,
            "MAX": 360,
            "MIN": 0,
            "NAME": "startingAngle",
            "TYPE": "float"
        }
    ],
    "ISFVSN": "2"
}
*/



vec4 getFromColor(vec2 inUV)	{
	return IMG_NORM_PIXEL(startImage, inUV);
}
vec4 getToColor(vec2 inUV)	{
	return IMG_NORM_PIXEL(endImage, inUV);
}



// Author: Fernando Kuteken
// License: MIT

#define PI 3.141592653589


vec4 transition (vec2 uv) {
  
  float offset = startingAngle * PI / 180.0;
  float angle = atan(uv.y - 0.5, uv.x - 0.5) + offset;
  float normalizedAngle = (angle + PI) / (2.0 * PI);
  
  normalizedAngle = normalizedAngle - floor(normalizedAngle);

  return mix(
    getFromColor(uv),
    getToColor(uv),
    step(normalizedAngle, progress)
    );
}



void main()	{
	gl_FragColor = transition(isf_FragNormCoord.xy);
}