221 lines
8.3 KiB
WebGPU Shading Language
221 lines
8.3 KiB
WebGPU Shading Language
#import bevy_pbr::{
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mesh_view_bindings::globals,
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forward_io::VertexOutput,
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}
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@group(2) @binding(0) var<uniform> ring_radius: f32;
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@group(2) @binding(1) var<uniform> jupiter_radius: f32;
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const jupiter_radius_Mm: f32 = 71.492;
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//fn ring_density(r: f32) -> f32 {
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// // r is in terms of megameters.
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//// if r < 92 {
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//// return 0.0;
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//// }
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//// if r > 226 {
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//// return 0.0;
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//// }
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//
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// let B0: f32 = 1.0;
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// let d0: f32 = 71492.0;
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// let lambda: f32 = 5000.0;
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// let alpha: f32 = 0.1;
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// let beta: f32 = 0.001;
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// let dist = r * 400;
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//
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// let brightness: f32 = B0 * exp(-(dist - d0) / lambda) * (1.0 + alpha * sin(beta * (dist - d0)));
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// return brightness * 1;
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//}
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//fn ring_density(r: f32) -> f32 {
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// if r < jupiter_radius_Mm {
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// return 0.0;
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// }
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// if r > jupiter_radius_Mm * 3 {
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// return 0.0;
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// }
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// let radius = (r - jupiter_radius_Mm) / (jupiter_radius_Mm * 2) + 1;
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// // Constants representing the approximate normalized start, peak, and end radii of the rings
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// let halo_start: f32 = 1.1;
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// let halo_peak: f32 = 1.2;
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// let halo_end: f32 = 1.3;
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//
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// let main_start: f32 = 1.4;
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// let main_peak: f32 = 1.5;
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// let main_end: f32 = 1.6;
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//
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// let gossamer_start: f32 = 1.7;
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// let gossamer_peak: f32 = 1.8;
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// let gossamer_end: f32 = 1.9;
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//
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// // Piecewise linear function for density approximation
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// if (radius >= halo_start && radius < halo_peak) {
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// return 1.0;
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// //return (radius - halo_start) / (halo_peak - halo_start);
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// } else if (radius >= halo_peak && radius <= halo_end) {
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// return 1.0 - (radius - halo_peak) / (halo_end - halo_peak);
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// } else if (radius >= main_start && radius < main_peak) {
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// return (radius - main_start) / (main_peak - main_start);
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// } else if (radius >= main_peak && radius <= main_end) {
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// return 1.0 - (radius - main_peak) / (main_end - main_peak);
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// } else if (radius >= gossamer_start && radius < gossamer_peak) {
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// return (radius - gossamer_start) / (gossamer_peak - gossamer_start);
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// } else if (radius >= gossamer_peak && radius <= gossamer_end) {
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// return 1.0 - (radius - gossamer_peak) / (gossamer_end - gossamer_peak);
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// }
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//
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// return 0.0; // Outside of rings, density is 0
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//}
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//fn ring_density(radius: f32) -> f32 {
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// // Define key radii for Jupiter's rings and gaps
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// let inner_radius: f32 = 1.806e5; // Inner boundary of the Halo ring
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// let halo_main_gap: f32 = 1.22e5; // Gap between Halo and Main rings
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// let main_amalthea_gap: f32 = 1.8e5; // Gap between Main and Amalthea Gossamer ring
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// let amalthea_thebe_gap: f32 = 2.24e5; // Gap between Amalthea and Thebe Gossamer rings
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// let outer_radius: f32 = 2.2e5; // Outer boundary of Thebe Gossamer ring
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// let metis_notch_inner: f32 = 1.28e5; // Inner boundary of Metis notch
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// let metis_notch_outer: f32 = 1.29e5; // Outer boundary of Metis notch
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//
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// // Density function
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// if radius > outer_radius {
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// return 0.0; // Beyond rings, density is zero
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// } else if radius > metis_notch_inner && radius < metis_notch_outer {
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// return 0.2; // Notch at the orbit of Metis
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// } else if radius > halo_main_gap && radius < main_amalthea_gap {
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// return 1.0; // Highest density in Main ring
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// } else if radius > amalthea_thebe_gap {
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// return 0.5; // Lower density in Thebe Gossamer ring
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// } else {
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// return 0.75; // Moderate density in other areas
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// }
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//}
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// Smooth step function for edge smoothing
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fn smooth_edge(start: f32, end: f32, value: f32, smooth_factor: f32) -> f32 {
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var x = ((value - start) / (end - start));
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if x < 0 {
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return 0.0;
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}
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if x > 1 {
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return 1.0;
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}
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return pow(x, smooth_factor) * (3.0 - 2.0 * x);
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}
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fn ring_density(radius: f32) -> f32 {
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let halo_inner: f32 = 92.0;
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let halo_outer: f32 = 122.5;
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let main_inner: f32 = 122.5;
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let main_outer: f32 = 129.0;
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let amalthea_inner: f32 = 129.0;
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let amalthea_outer: f32 = 182.0;
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let thebe_inner: f32 = 129.0;
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let thebe_outer: f32 = 229.0;
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let metis_notch_center: f32 = 128.0;
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let metis_notch_width: f32 = 0.6;
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let halo_brightness: f32 = 0.4;
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let main_brightness: f32 = 1.0;
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let almathea_brightness: f32 = 0.3;
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let thebe_brightness: f32 = 0.2;
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let smooth_factor: f32 = 2.0; // Smooth edges
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if radius < halo_inner || radius > thebe_outer {
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return 0.0;
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} else if radius >= halo_inner && radius <= halo_outer {
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return halo_brightness * smooth_edge(halo_inner, halo_outer, radius, smooth_factor);
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} else if radius >= main_inner && radius <= main_outer {
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var metis_notch_effect = 1.0;
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if radius > metis_notch_center - metis_notch_width * 0.5 && radius < metis_notch_center + metis_notch_width * 0.5 {
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metis_notch_effect = 0.5 * (1.0 - smooth_edge(metis_notch_center - metis_notch_width * 0.5, metis_notch_center + metis_notch_width * 0.5, radius, smooth_factor));
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}
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return main_brightness * metis_notch_effect * smooth_edge(main_inner, main_outer, radius, smooth_factor);
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} else if radius >= amalthea_inner && radius <= amalthea_outer {
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return almathea_brightness * smooth_edge(amalthea_inner, amalthea_outer, radius, smooth_factor);
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} else if radius >= thebe_inner && radius <= thebe_outer {
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return thebe_brightness * smooth_edge(thebe_inner, thebe_outer, radius, smooth_factor);
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}
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return 0.0;
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}
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fn smooth_edge2(start: f32, end: f32, value: f32) -> f32 {
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var x: f32 = (value - start) / (end - start);
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return 4 * x * x * (1 - x * x);
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}
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fn ring_density2(radius: f32) -> f32 {
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let halo_inner: f32 = 92.0;
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let halo_outer: f32 = 122.5;
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let main_inner: f32 = 122.5;
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let main_outer: f32 = 129.0;
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let amalthea_inner: f32 = 129.0;
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let amalthea_outer: f32 = 182.0;
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let thebe_inner: f32 = 129.0;
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let thebe_outer: f32 = 229.0;
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let metis_notch_center: f32 = 128.0;
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let metis_notch_width: f32 = 0.6;
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let halo_brightness: f32 = 0.3;
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let main_brightness: f32 = 1.0;
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let almathea_brightness: f32 = 0.2;
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let thebe_brightness: f32 = 0.2;
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let inner_smooth_factor: f32 = 2.0; // Smooth inner edges
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let outer_smooth_factor: f32 = 1.5; // Rougher outer edges
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var density: f32 = 0.0;
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if (radius >= halo_inner && radius <= halo_outer) {
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density = halo_brightness * smooth_edge2(halo_inner, halo_outer, radius);
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} else if (radius >= main_inner && radius <= main_outer) {
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var metis_notch_effect: f32 = 1.0;
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if (radius > metis_notch_center - metis_notch_width * 0.5 && radius < metis_notch_center + metis_notch_width * 0.5) {
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metis_notch_effect = 0.5 * (1.0 - smooth_edge2(metis_notch_center - metis_notch_width * 0.5, metis_notch_center + metis_notch_width * 0.5, radius));
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}
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density = main_brightness * metis_notch_effect * smooth_edge2(main_inner, main_outer, radius);
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} else {
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if (radius >= amalthea_inner && radius <= amalthea_outer) {
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density = almathea_brightness * smooth_edge2(amalthea_inner, amalthea_outer, radius);
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}
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if (radius >= thebe_inner && radius <= thebe_outer) {
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density += thebe_brightness * smooth_edge2(thebe_inner, thebe_outer, radius);
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}
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}
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return density;
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}
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@fragment
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fn fragment(in: VertexOutput) -> @location(0) vec4<f32> {
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let jupiter_percent = jupiter_radius / ring_radius;
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let color = vec3<f32>(0.3, 0.3, 0.3);
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var alpha = 0.04;
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let r_uv = 2 * distance(in.uv, vec2<f32>(0.5));
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let r = r_uv * ring_radius / jupiter_radius * jupiter_radius_Mm;
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alpha *= ring_density2(r);
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if alpha <= 0.0 {
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return vec4<f32>(color, alpha);
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}
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//alpha *= (sin(11*r / 0.71 * 3.1415) + 1) / 2;
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//alpha *= (cos(r / 0.72 * 3.1415) + 1) / 2;
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if in.uv[0] < 0.5 {
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let dist = (0.5 - in.uv[0]) * 2.0; // 0.0=jupiter's center, 1.0=edge of the ring
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let side_dist = abs(in.uv[1] - 0.5);
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let cutoff = 0.5 * jupiter_percent * cos(dist);
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if side_dist < cutoff {
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return vec4<f32>(color, 0.0);
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}
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let fuzzy_boundary = 0.01;
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if side_dist < cutoff + fuzzy_boundary {
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return vec4<f32>(color, alpha * (side_dist - cutoff) / fuzzy_boundary);
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}
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}
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return vec4<f32>(color, alpha);
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}
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