#version 330 core

in VS_OUT {
    vec2 UvPosition;
    vec2 Texture;
    vec3 Color;
    vec2 Light;
} fs_in;

uniform sampler2D textureAtlas;
uniform vec2 windowSize;
uniform float DayTime;

vec3 rgb2hsv(vec3 c)
{
    vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
    vec4 p = mix(vec4(c.bg, K.wz), vec4(c.gb, K.xy), step(c.b, c.g));
    vec4 q = mix(vec4(p.xyw, c.r), vec4(c.r, p.yzx), step(p.x, c.r));

    float d = q.x - min(q.w, q.y);
    float e = 1.0e-10;
    return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + e)), d / (q.x + e), q.x);
}

vec3 hsv2rgb(vec3 c)
{
    vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
    vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
    return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
}

void main() {
	vec4 color = texture(textureAtlas,fs_in.Texture);
    if (color.a < 0.3)
        discard;

    vec3 hsvColor = rgb2hsv(color.xyz);
    hsvColor+=fs_in.Color;
	color = vec4(hsv2rgb(hsvColor),1);

	float light = fs_in.Light.x / 15.0;
	float skyLight = (fs_in.Light.y / 15.0) * DayTime;

    float faceLight = clamp(light + skyLight,0.2,1.0);

    color = vec4(color.rgb * faceLight, color.a);
	gl_FragColor = color;
}