initial commit.

1 files changed, 279 insertions, 0 deletions

diff --git a/res/sdr/sky_halo_old.fs b/res/sdr/sky_halo_old.fs
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+++ b/res/sdr/sky_halo_old.fs
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+#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;
+
+void
+main()
+{
+	/*
+	 * Reconstruct a world-space direction for this screen pixel.
+	 */
+	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
+	);
+
+	vec3 moon_direction = -sun_direction;
+
+	/*
+	 * Vertical sky gradient.
+	 */
+	float height = smoothstep(
+		-0.20,
+		0.80,
+		view_direction.y
+	);
+
+	/*
+	 * Day/night transition based on the sun's elevation.
+	 */
+	float day_amount = smoothstep(
+		-0.10,
+		0.12,
+		sun_direction.y
+	);
+
+	float night_amount = 1.0 - day_amount;
+
+	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
+	);
+
+	/*
+	 * Sunrise and sunset colouring.
+	 */
+	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_alignment = dot(
+		view_direction,
+		sun_direction
+	);
+
+	float sun_facing = max(
+		sun_alignment,
+		0.0
+	);
+
+	/*
+	 * Avoid pow(): x^4 is sufficient for the broad sunset effect.
+	 */
+	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;
+
+	/*
+	 * Sun halo.
+	 *
+	 * The values are precalculated cosine values. Since both
+	 * view_direction and sun_direction are normalized, their dot
+	 * product is the cosine of the angle between them.
+	 *
+	 * Wide halo:
+	 *     outer edge: 18 degrees
+	 *     inner edge: 3 degrees
+	 *
+	 * Core halo:
+	 *     outer edge: 7 degrees
+	 *     inner edge: 1 degree
+	 */
+	float sun_wide = smoothstep(
+		0.9510565,
+		0.9986295,
+		sun_alignment
+	);
+
+	float sun_core = smoothstep(
+		0.9925462,
+		0.9998477,
+		sun_alignment
+	);
+
+	/*
+	 * Moon halo.
+	 *
+	 * Because the moon is directly opposite the sun in this model,
+	 * its alignment is the negative sun alignment.
+	 *
+	 * Wide halo:
+	 *     outer edge: 14 degrees
+	 *     inner edge: 2 degrees
+	 *
+	 * Core halo:
+	 *     outer edge: 5 degrees
+	 *     inner edge: 0.5 degrees
+	 */
+	float moon_alignment = -sun_alignment;
+
+	float moon_wide = smoothstep(
+		0.9702957,
+		0.9993908,
+		moon_alignment
+	);
+
+	float moon_core = smoothstep(
+		0.9961947,
+		0.9999619,
+		moon_alignment
+	);
+
+	/*
+	 * Fade each halo near and below the horizon.
+	 *
+	 * These ranges are deliberately broader than the symbol fade so
+	 * the surrounding light disappears gradually.
+	 */
+	float sun_above_horizon = smoothstep(
+		-0.12,
+		0.04,
+		sun_direction.y
+	);
+
+	float moon_above_horizon = smoothstep(
+		-0.10,
+		0.04,
+		moon_direction.y
+	);
+
+	/*
+	 * Warm the sun halo around sunrise and sunset.
+	 */
+	vec3 daylight_glow = vec3(
+		1.00,
+		0.82,
+		0.38
+	);
+
+	vec3 sunset_glow = vec3(
+		1.00,
+		0.25,
+		0.035
+	);
+
+	vec3 sun_glow_colour = mix(
+		daylight_glow,
+		sunset_glow,
+		twilight
+	);
+
+	vec3 moon_glow_colour = vec3(
+		0.32,
+		0.46,
+		0.82
+	);
+
+	/*
+	 * Broad component blends the sprite into the sky.
+	 * Core component makes the centre appear luminous.
+	 */
+	float sun_glow =
+		(
+			sun_wide * 0.13 +
+			sun_core * 0.32
+		) *
+		sun_above_horizon;
+
+	float moon_glow =
+		(
+			moon_wide * 0.08 +
+			moon_core * 0.17
+		) *
+		moon_above_horizon *
+		night_amount;
+
+	/*
+	 * Soft screen-like blending. This brightens the sky without
+	 * immediately clipping bright daytime colours to white.
+	 */
+	sky +=
+		(1.0 - sky) *
+		sun_glow_colour *
+		sun_glow;
+
+	sky +=
+		(1.0 - sky) *
+		moon_glow_colour *
+		moon_glow;
+
+	finalColor = vec4(
+		clamp(sky, 0.0, 1.0),
+		1.0
+	);
+}