#version 300 es

// fragment shaders don't have a default precision so we need
// to pick one. mediump is a good default. It means "medium precision"
precision mediump float;

in vec4 pos;
in vec3 v_surfaceToLight;
uniform vec4 u_color;

out vec4 outColor;

void main() {
    vec4 fragNormal = normalize(pos);
    float u_light = 0.3;
    float light = max(dot(fragNormal.xyz, normalize(v_surfaceToLight).xyz), u_light);
    vec3 baseColor = vec3(0, 0, 1);
    vec3 maxColor = vec3(1, 0, 0);
    float y = pos.z;
    if (y < 0.0) {
        y = y * -1.0;
    }
    vec3 color = mix(baseColor, maxColor, y);
    outColor = vec4(color, 1.0);
    outColor.rgb *= light;
}