#version 130

#include "/settings.glsl"

uniform float viewHeight;
uniform float viewWidth;
uniform mat4 gbufferModelView;
uniform mat4 gbufferProjectionInverse;
uniform vec3 fogColor;
uniform vec3 skyColor;
uniform int worldTime;

in vec2 TexCoords;
in vec2 LightmapCoords;
in vec3 Normal;
in vec4 Color;

uniform sampler2D texture;

in vec4 starData; //rgb = star color, a = flag for weather or not this pixel is a star.

float fogify(float x, float w) {
	return w / (x * x + w);
}

float smoothTransition(float time) {
    if (time >= 0.0f && time <= 1000.0f) {
        return time / 1000.0f; // Transition from 0 to 1
    } else if (time > 1000.0f && time < 12000.0f) {
        return 1.0f; // Fully enabled
    } else if (time >= 12000.0f && time <= 13000.0f) {
        return 1.0f - (time - 12000.0f) / 1000.0f; // Transition from 1 to 0
    } else {
        return 0.0f; // Fully disabled
    }
}

vec3 calcSkyColor(vec3 pos) {
	float upDot = dot(pos, gbufferModelView[1].xyz);
	
	#if GREY_WEATHER == 0
	return mix(skyColor, fogColor, fogify(max(upDot, 0.0), 0.25));
	#else
	float state = smoothTransition(worldTime);
	vec3 color_sky = mix(mix(skyColor, fogColor, fogify(max(upDot, 0.0), 0.25)), vec3(0.75, 0.75, 0.76), state);
	return color_sky;
	#endif
}

void main()
{
	vec3 color;
	if (starData.a > 0.5) {
		color = starData.rgb * 0.65;
	}
	else {
		vec4 pos = vec4(gl_FragCoord.xy / vec2(viewWidth, viewHeight) * 2.0 - 1.0, 1.0, 1.0);
		pos = gbufferProjectionInverse * pos;
		color = calcSkyColor(normalize(pos.xyz));
	}
	
	/* DRAWBUFFERS:012 */
    gl_FragData[0] = vec4(color, 1.0);
	gl_FragData[1] = vec4(Normal * 0.5f + 0.5f, 1.0f);
    gl_FragData[2] = vec4(vec3(LightmapCoords.x * 1, LightmapCoords.y * 0.5, 0), 1);
}