vertex.vert

// our vertex data
attribute vec3 aPosition;

// our texcoordinates
attribute vec2 aTexCoord;

// this is a variable that will be shared with the fragment shader
// we will assign the attribute texcoords to the varying texcoords to move them from the vert shader to the frag shader
// it can be called whatever you want but often people prefiv it with 'v' to indicate that it is a varying
varying vec2 vTexCoord;

void main() {

  // copy the texture coordinates
  vTexCoord = aTexCoord;

  // copy the position data into a vec4, using 1.0 as the w component
  vec4 positionVec4 = vec4(aPosition, 1.0);
  positionVec4.xy = positionVec4.xy * 2.0 - 1.0;
//   positionVec4.x *= aPosition.x / aPosition.y;
  // send the vertex information on to the fragment shader
  gl_Position = positionVec4;
}