1 files changed, 92 insertions, 0 deletions
diff --git a/res/sdr/sky_old.fs b/res/sdr/sky_old.fs
new file mode 100644
index 0000000..039691c
--- /dev/null
+++ b/res/sdr/sky_old.fs
@@ -0,0 +1,92 @@
+#version 330
+
+uniform vec2 resolution;
+uniform vec3 camera_forward;
+uniform vec3 camera_right;
+uniform vec3 camera_up;
+
+uniform vec3 sun_direction;
+
+uniform float aspect_ratio;
+uniform float tan_half_fovy;
+
+out vec4 finalColor;
+
+float
+angular_halo(float alignment, float outer_cos, float inner_cos) {
+	/*
+	 * alignment is 1.0 while looking directly at the celestial body.
+	 *
+	 * outer_cos = cos(outer halo angle)
+	 * inner_cos = cos(inner halo angle)
+	 */
+	return smoothstep(
+		outer_cos,
+		inner_cos,
+		alignment
+	);
+}
+
+void
+main() {
+	vec2 screen = gl_FragCoord.xy / resolution;
+	vec2 ndc = screen * 2.0 - 1.0;
+
+	vec3 view_direction = normalize(
+		camera_forward +
+		camera_right * ndc.x * aspect_ratio * tan_half_fovy +
+		camera_up * ndc.y * tan_half_fovy
+	);
+
+	/*
+	 * Controls the vertical gradient.
+	 *
+	 * -0.2 includes some colour below the horizon so the transition
+	 * remains smooth while looking downward.
+	 */
+	float height = smoothstep(-0.20, 0.80, view_direction.y);
+
+	/*
+	 * The world becomes mostly daylight shortly after the sun crosses
+	 * the horizon, and mostly night shortly after it sets.
+	 */
+	float day_amount = smoothstep(-0.10, 0.12, sun_direction.y);
+
+	vec3 night_horizon = vec3(0.055, 0.045, 0.110);
+	vec3 night_zenith = vec3(0.005, 0.008, 0.025);
+
+	vec3 day_horizon = vec3(0.620, 0.780, 0.920);
+	vec3 day_zenith = vec3(0.080, 0.280, 0.620);
+
+	vec3 night_sky = mix(night_horizon, night_zenith, height);
+	vec3 day_sky = mix(day_horizon, day_zenith, height);
+
+	vec3 sky = mix(night_sky, day_sky, day_amount);
+
+	/*
+	 * Stylized sunrise/sunset colour.
+	 *
+	 * This is strongest:
+	 * - near the horizon;
+	 * - while the sun is near the horizon;
+	 * - while looking toward the sun.
+	 */
+	float horizon =
+		1.0 - smoothstep(0.0, 0.35, abs(view_direction.y));
+
+	float twilight =
+		1.0 - smoothstep(0.02, 0.28, abs(sun_direction.y));
+
+	float sun_facing = max(dot(view_direction, sun_direction), 0.0);
+	float sun_facing_2 = sun_facing * sun_facing;
+	float sun_facing_4 = sun_facing_2 * sun_facing_2;
+
+	vec3 sunset_colour = vec3(0.65, 0.16, 0.035);
+
+	sky += sunset_colour *
+		horizon *
+		twilight *
+		sun_facing_4;
+
+	finalColor = vec4(min(sky, vec3(1.0)), 1.0);
+}