#version 300 es

precision mediump float;

uniform sampler2D u_atlas;

in vec2 v_uv;
in vec3 v_fg;
in vec3 v_bg;

out vec4 o_col;

void main() {
    float a = texture(u_atlas, v_uv).r;
    o_col = vec4(mix(v_bg, v_fg, a), 1.0);
}