63 lines
No EOL
1.7 KiB
Text
63 lines
No EOL
1.7 KiB
Text
include "pipelines/common.glsl"
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compute_shader [[
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layout(local_size_x = 16, local_size_y = 16, local_size_z = 1) in;
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layout (rg32f, binding = 0) uniform writeonly image2D u_output;
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layout(std140, binding = 4) uniform Data {
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float u_bot;
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float u_top;
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float u_distribution_rayleigh;
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float u_distribution_mie;
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vec4 u_scatter_rayleigh;
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vec4 u_scatter_mie;
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vec4 u_absorb_mie;
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vec4 u_sunlight;
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vec4 u_resolution;
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};
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vec2 ray_sphere_intersect(vec3 r0, vec3 rd, vec3 s0, float sr) {
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vec3 s0_r0 = s0 - r0;
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float tc = dot(s0_r0, rd);
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float d2 = dot(s0_r0, s0_r0) - tc * tc;
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float sr2 = sr * sr;
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if (d2 > sr2) return vec2(-1);
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float td2 = sr2 - d2;
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float td = sqrt(td2);
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return vec2(tc - td, tc + td);
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}
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vec3 getTopAtmo(vec3 p, vec3 dir) {
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vec2 t = ray_sphere_intersect(p, dir, vec3(0), u_top);
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return p + t.y * dir.xyz;
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}
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float opticalDepth(vec3 a, vec3 b, float distribution) {
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float l = length(a - b);
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int step_count = 50;
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float dens = 0;
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vec3 step = (b - a) / step_count;
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float step_len = l / step_count;
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vec3 p = a;
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for (int i = 0; i < step_count; ++i) {
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float h = length(p + step * 0.5);
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float tmp = exp(min(0, (u_bot - h) / distribution));
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dens += step_len * tmp;
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p += step;
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}
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return dens;
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}
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void main() {
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const vec2 xy = gl_GlobalInvocationID.xy / u_resolution.xy;
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float angle = xy.x * M_PI * 0.5;
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const vec3 p = vec3(0, u_bot + (u_top - u_bot) * xy.y, 0);
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const vec3 dir = vec3(sqrt(saturate(1 - xy.x * xy.x)), xy.x, 0);
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float rayleigh = opticalDepth(p, getTopAtmo(p, dir), u_distribution_rayleigh);
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float mie = opticalDepth(p, getTopAtmo(p, dir), u_distribution_mie);
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imageStore(u_output, ivec2(gl_GlobalInvocationID.xy), vec4(rayleigh, mie, 0, 0));
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}
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]] |