渐变打开

#ifdef GL_ES
precision highp float;
#endif

varying vec2 v_texCoord;

void main(void)
{
    vec4 col = texture2D(CC_Texture0,v_texCoord);
    float fDiatance = distance( v_texCoord,vec2(0.5,0.5) );
    gl_FragColor = vec4(0.0,0.0,smoothstep(0.0,1.0-sin( CC_Time.z*0.5 ),abs(fDiatance)*0.5 ) );
}