" \n\ #ifdef GL_ES \n\ precision lowp float; \n\ #endif \n\ \n\ varying vec4 v_fragmentColor; \n\ varying vec2 v_texCoord; \n\ uniform sampler2D CC_Texture0; \n\ uniform vec3 v_effectColor; \n\ \n\ void main() \n\ { \n\ float dist = texture2D(CC_Texture0, v_texCoord).a; \n\ //todo:Implementation 'fwidth' for glsl 1.0 \n\ //float width = fwidth(dist); \n\ //assign width for constant will lead to a little bit fuzzy,it's temporary measure.\n\ float width = 0.04; \n\ float alpha = smoothstep(0.5-width, 0.5+width, dist); \n\ //glow \n\ float mu = smoothstep(0.5, 1.0, sqrt(dist)); \n\ vec3 rgb = v_effectColor*(1.0-alpha) + v_fragmentColor.rgb*alpha; \n\ gl_FragColor = vec4(rgb, max(alpha,mu)); \n\ } \n\ ";