Distorted Android

// Pull P=(v.x,v.y) towards center of the effect with P' = P + (1-h)*dist(S-P)

// when h>1 we are pushing points away from S: P' = P + (1/h-1)*dist(S-P)

//////////////////////////////////////////////////////////////////////////////////////////////

// PINCH EFFECT

//

// Pull P=(v.x,v.y) towards the line that

// a) passes through the center of the effect

// b) forms angle defined in the 2nd interpolated value with the X-axis

// with P' = P + (1-h)*dist(line to P)

// when h>1 we are pushing points away from S: P' = P + (1/h-1)*dist(line to P)

void pinch(in int effect,inout vec4 v)

  {

  vec2 center = vUniforms[effect+1].yz;

  vec2 ps = center-v.xy;

  float h = vUniforms[effect].x;

  float t = degree(vUniforms[effect+2],center,ps) * (1.0-h)/max(1.0,h);

  float angle = vUniforms[effect].y;

  vec2 dir = vec2(sin(angle),-cos(angle));

  v.xy += t*dot(ps,dir)*dir;

  }

    else if( vType[i]==PINCH  ) pinch  (3*i,v);