113 lines
3.8 KiB
GLSL
113 lines
3.8 KiB
GLSL
#version 330 core
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out vec4 FragColor;
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in vec3 fragPos;
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uniform float timeOfDay;
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float hash(vec3 p) {
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p = fract(p * 0.3183099 + 0.1);
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p *= 17.0;
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return fract(p.x * p.y * p.z * (p.x + p.y + p.z));
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}
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vec3 getSkyColor(vec3 dir, float tod) {
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float height = dir.y;
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float t = fract(tod);
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float angle = t * 6.28318530718;
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vec3 sunDir = normalize(vec3(cos(angle), sin(angle) * 0.5, sin(angle)));
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float sunDot = max(dot(dir, sunDir), 0.0);
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vec3 nightTop = vec3(0.01, 0.03, 0.08);
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vec3 nightHorizon = vec3(0.04, 0.06, 0.12);
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vec3 dayTop = vec3(0.25, 0.55, 1.00);
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vec3 dayHorizon = vec3(0.75, 0.88, 1.00);
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vec3 sunriseTop = vec3(0.45, 0.32, 0.55);
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vec3 sunriseHorizon = vec3(1.10, 0.60, 0.30);
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vec3 sunsetTop = vec3(0.55, 0.35, 0.45);
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vec3 sunsetHorizon = vec3(1.05, 0.45, 0.20);
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vec3 skyTop, skyHorizon;
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if (t < 0.25) {
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float f = t * 4.0;
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skyTop = mix(nightTop, sunriseTop, f);
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skyHorizon = mix(nightHorizon, sunriseHorizon, f);
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} else if (t < 0.5) {
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float f = (t-0.25)*4.0;
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skyTop = mix(sunriseTop, dayTop, f);
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skyHorizon = mix(sunriseHorizon, dayHorizon, f);
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} else if (t < 0.75) {
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float f = (t-0.5)*4.0;
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skyTop = mix(dayTop, sunsetTop, f);
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skyHorizon = mix(dayHorizon, sunsetHorizon, f);
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} else {
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float f = (t-0.75)*4.0;
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skyTop = mix(sunsetTop, nightTop, f);
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skyHorizon = mix(sunsetHorizon, nightHorizon, f);
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}
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float horizonMix = smoothstep(-0.2, 0.45, height);
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vec3 skyColor = mix(skyHorizon, skyTop, horizonMix);
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// Warm haze near the horizon for softer day transitions
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float hazeAmount = exp(-max(height, 0.0) * 12.0);
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vec3 hazeColor = mix(skyHorizon * 0.8, vec3(1.0, 0.95, 0.9), 0.6);
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vec3 sunCol = vec3(1.0, 0.95, 0.8);
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float sunGlow = pow(sunDot, 128.0) * 2.5;
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float sunDisc = smoothstep(0.9995, 0.9998, sunDot);
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float atmGlow = pow(sunDot, 8.0) * 0.6;
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float mie = pow(sunDot, 12.0);
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float sunVisibility = smoothstep(-0.12, 0.15, sunDir.y); // smooth fade in/out
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skyColor += sunCol * (sunDisc + atmGlow + sunGlow * 0.35) * sunVisibility;
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// Forward-scattered haze brightens the horizon when the sun is low
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vec3 forwardHaze = hazeColor * mie * 0.25 * sunVisibility;
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skyColor += forwardHaze;
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skyColor += hazeColor * hazeAmount * 0.18 * (0.3 + sunVisibility);
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float night = 1.0 - sunVisibility;
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if (night > 0.0) {
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vec3 p = dir * 160.0;
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vec3 i = floor(p);
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vec3 f = fract(p);
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float stars = 0.0;
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for (int z=-1; z<=1; z++)
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for (int y=-1; y<=1; y++)
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for (int x=-1; x<=1; x++) {
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vec3 o = vec3(x,y,z);
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vec3 pos = i + o;
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float h = hash(pos);
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if (h > 0.99) {
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vec3 center = o + 0.5 + (hash(pos+vec3(7,13,21))-0.5)*0.8;
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float d = length(f - center);
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float star = 1.0 - smoothstep(0.0, 0.12, d);
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star *= (h - 0.99)*100.0;
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stars += star;
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}
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}
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stars = pow(stars, 1.4);
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stars *= night;
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stars *= smoothstep(-0.1, 0.25, height);
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// Subtle Milky Way band to add structure to the night sky
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vec3 galaxyAxis = normalize(vec3(0.2, 0.85, -0.5));
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float galaxyBand = 1.0 - abs(dot(dir, galaxyAxis)); // highest when perpendicular to the axis
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galaxyBand = pow(max(galaxyBand, 0.0), 2.5); // soften and widen
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vec3 galaxyCol = vec3(0.65, 0.78, 1.0) * galaxyBand * 0.5;
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galaxyCol *= smoothstep(-0.15, 0.25, height);
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skyColor += vec3(1.0, 0.95, 0.9) * stars * 2.5 + galaxyCol;
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}
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return skyColor;
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}
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void main() {
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vec3 dir = normalize(fragPos);
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vec3 col = getSkyColor(dir, timeOfDay);
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FragColor = vec4(col, 1.0);
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}
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