" \n\ #ifdef GL_ES \n\ precision lowp float; \n\ #endif \n\ \n\ varying vec4 v_fragmentColor; \n\ varying vec2 v_texCoord; \n\ uniform sampler2D u_texture; \n\ uniform float u_alpha_value; \n\ \n\ void main() \n\ { \n\ vec4 texColor = texture2D(u_texture, v_texCoord); \n\ \n\ // mimic: glAlphaFunc(GL_GREATER) \n\ // pass if ( incoming_pixel >= u_alpha_value ) => fail if incoming_pixel < u_alpha_value \n\ \n\ if ( texColor.a <= u_alpha_value ) \n\ discard; \n\ \n\ gl_FragColor = texColor * v_fragmentColor; \n\ } \n\ ";