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102 lines
2.7 KiB
GLSL
102 lines
2.7 KiB
GLSL
#include <random.glsl>
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uniform sampler2D t_map;
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vec2 pos_to_uv(vec2 pos) {
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vec2 uv_pos = (pos + 16) / 32768.0;
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return vec2(uv_pos.x, 1.0 - uv_pos.y);
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}
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// textureBicubic from https://stackoverflow.com/a/42179924
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vec4 cubic(float v) {
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vec4 n = vec4(1.0, 2.0, 3.0, 4.0) - v;
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vec4 s = n * n * n;
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float x = s.x;
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float y = s.y - 4.0 * s.x;
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float z = s.z - 4.0 * s.y + 6.0 * s.x;
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float w = 6.0 - x - y - z;
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return vec4(x, y, z, w) * (1.0/6.0);
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}
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vec4 textureBicubic(sampler2D sampler, vec2 texCoords) {
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vec2 texSize = textureSize(sampler, 0);
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vec2 invTexSize = 1.0 / texSize;
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texCoords = texCoords * texSize - 0.5;
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vec2 fxy = fract(texCoords);
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texCoords -= fxy;
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vec4 xcubic = cubic(fxy.x);
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vec4 ycubic = cubic(fxy.y);
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vec4 c = texCoords.xxyy + vec2 (-0.5, +1.5).xyxy;
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vec4 s = vec4(xcubic.xz + xcubic.yw, ycubic.xz + ycubic.yw);
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vec4 offset = c + vec4 (xcubic.yw, ycubic.yw) / s;
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offset *= invTexSize.xxyy;
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vec4 sample0 = texture(sampler, offset.xz);
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vec4 sample1 = texture(sampler, offset.yz);
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vec4 sample2 = texture(sampler, offset.xw);
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vec4 sample3 = texture(sampler, offset.yw);
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float sx = s.x / (s.x + s.y);
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float sy = s.z / (s.z + s.w);
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return mix(
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mix(sample3, sample2, sx), mix(sample1, sample0, sx)
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, sy);
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}
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float alt_at(vec2 pos) {
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return texture(t_map, pos_to_uv(pos)).a * (1300.0) + 140.0;
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//+ (texture(t_noise, pos * 0.002).x - 0.5) * 64.0;
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return 0.0
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+ pow(texture(t_noise, pos * 0.00005).x * 1.4, 3.0) * 1000.0
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+ texture(t_noise, pos * 0.001).x * 100.0
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+ texture(t_noise, pos * 0.003).x * 30.0;
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}
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vec2 splay(vec2 pos) {
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return pos * pow(length(pos) * 0.5, 3.0);
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}
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vec3 lod_norm(vec2 pos) {
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const float SAMPLE_W = 32;
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float altx0 = alt_at(pos + vec2(-1, 0) * SAMPLE_W);
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float altx1 = alt_at(pos + vec2(1, 0) * SAMPLE_W);
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float alty0 = alt_at(pos + vec2(0, -1) * SAMPLE_W);
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float alty1 = alt_at(pos + vec2(0, 1) * SAMPLE_W);
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float slope = abs(altx1 - altx0) + abs(alty0 - alty1);
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return normalize(vec3(
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(altx0 - altx1) / SAMPLE_W,
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(alty0 - alty1) / SAMPLE_W,
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SAMPLE_W / (slope + 0.00001) // Avoid NaN
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));
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}
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vec3 lod_pos(vec2 v_pos, vec2 focus_pos) {
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vec2 hpos = focus_pos.xy + splay(v_pos) * 1000000.0;
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// Remove spiking by "pushing" vertices towards local optima
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vec2 nhpos = hpos;
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for (int i = 0; i < 3; i ++) {
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nhpos -= lod_norm(hpos).xy * 15.0;
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}
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hpos = hpos + normalize(nhpos - hpos + 0.001) * min(length(nhpos - hpos), 32);
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return vec3(hpos, alt_at(hpos));
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}
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vec3 lod_col(vec2 pos) {
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//return vec3(0, 0.5, 0);
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return textureBicubic(t_map, pos_to_uv(pos)).rgb;
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//+ (texture(t_noise, pos * 0.04 + texture(t_noise, pos * 0.005).xy * 2.0 + texture(t_noise, pos * 0.06).xy * 0.6).x - 0.5) * 0.1;
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}
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