Shockwave.fs

Code

uniform sampler2D inputImage;
uniform float positionVal;
uniform float distortion;
uniform float magnitude;
uniform vec2 center;
uniform int background;
precision mediump float;
/*{
  "DESCRIPTION": "",
  "CREDIT": "by VIDVOX",
  "CATEGORIES": [
    "Distortion Effect"
  ],
  "INPUTS": [
    {
      "NAME": "inputImage",
      "TYPE": "image"
    },
    {
      "NAME": "positionVal",
      "TYPE": "float",
      "MIN": 0,
      "MAX": 1,
      "DEFAULT": 0
    },
    {
      "NAME": "distortion",
      "TYPE": "float",
      "MIN": 1,
      "MAX": 20,
      "DEFAULT": 10
    },
    {
      "NAME": "magnitude",
      "TYPE": "float",
      "MIN": 0,
      "MAX": 0.2,
      "DEFAULT": 0.08
    },
    {
      "NAME" : "center",
      "TYPE" : "point2D",
      "MAX" : [
        1,
        1
      ],
      "DEFAULT" : [
        0.5,
        0.5
      ],
      "MIN" : [
        0,
        0
      ]
    },
    {
      "NAME": "background",
      "TYPE": "bool",
      "DEFAULT": 1
    }
  ]
}*/



void main()
{
	//	do this junk so that the ripple starts from nothing
	vec2 uv = (gl_FragCoord.xy / u_resolution.xy).xy;
	vec2 texCoord = uv;
	vec2 mod_center = center;
	vec4 color = vec4(0.0);
	float dist = distance(uv, mod_center);
	float adjustedTime = (positionVal * u_resolution.x/u_resolution.y - magnitude)/(1.0 - magnitude);

	if ( (dist <= (adjustedTime + magnitude)) && (dist >= (adjustedTime - magnitude)) ) 	{
		float diff = (dist - adjustedTime); 
		float powDiff = 1.0 - pow(abs(diff*distortion), 
								0.8); 
		float diffTime = diff  * powDiff; 
		vec2 diffUV = normalize(uv - mod_center); 
		texCoord = uv + (diffUV * diffTime);
		color = texture2D(inputImage, texCoord);
	}
	else if (background)	{
		color = texture2D(inputImage, texCoord);
	}
	gl_FragColor = color;
}