Something down in the food chain already uses bitflags, so might as well switch to them
#ifdef GL_ES
precision mediump float;
#endif
attribute vec2 vertex;
attribute vec4 color;
varying vec4 vcolor;
uniform mat4 mvp;
void main()
{
vec4 p = mvp * vec4(vertex, 0.0, 1.0);
gl_Position = p;
vcolor = color;
}