attribute vec4 a_position;
attribute vec2 a_texCoord;
uniform vec2 u_diffUVSize;
varying vec4 v_vertexPos;
varying vec2 v_texCoord;
varying vec2 v_normTexCoord;

void main()
{
    gl_Position = a_position;
    v_vertexPos = gl_Position;
    v_texCoord = a_texCoord;
    v_normTexCoord = a_texCoord * 2.0 - 1.0;
}
