#version 330 core
in vec3 pos;
out vec4 fragColor;
uniform sampler2DArray textureAtlas;
uniform float DayTime;
uniform vec4 sunTexture;
uniform float sunTextureLayer;
uniform vec4 moonTexture;
uniform float moonTextureLayer;
const vec4 DaySkyColor = vec4(0.49, 0.66, 1, 1);
const vec3 SunPos = vec3(0, 0.1, 0.5);
const vec3 MoonPos = vec3(0, 0.1, -0.5);
vec3 TransformTextureCoord(vec4 TextureAtlasCoords, vec2 UvCoords, float Layer) {
float x = TextureAtlasCoords.x;
float y = TextureAtlasCoords.y;
float w = TextureAtlasCoords.z;
float h = TextureAtlasCoords.w;
vec2 A = vec2(x, 1 - y - h);
vec2 B = vec2(x + w, 1 - y);
vec2 transformed = A + UvCoords * (B - A);
return vec3(transformed.x, transformed.y, Layer);
}
vec4 Sun() {
vec3 sunDelta = (pos - SunPos) * 3.0f;
float distanceToSun = length(sunDelta);
vec4 sunColor = texture(textureAtlas, TransformTextureCoord(sunTexture, (vec2(sunDelta.xy) + 0.5f), sunTextureLayer));
vec4 sun = mix(vec4(0, 0, 0, 1), sunColor, clamp(1 - distanceToSun * 2.0f, 0, 1));
return sun;
}
vec4 Moon() {
vec3 moonDelta = (pos - MoonPos) * 4.5f;
float distanceToMoon = length(moonDelta);
vec4 moonColor = texture(textureAtlas, TransformTextureCoord(moonTexture, (vec2(moonDelta.xy) + 0.5f), moonTextureLayer));
vec4 moon = mix(vec4(0, 0, 0, 1),moonColor, clamp(1 - distanceToMoon * 2.0f, 0, 1));
return moon;
}
void main() {
vec4 starColor = vec4(0.0f, 0.04f, 0.06f, 1.0f);
fragColor = mix(starColor, DaySkyColor, DayTime);
fragColor += Sun();
fragColor += Moon();
}
