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maszyna/shaders/postfx_gtao.frag

110 lines
4.2 KiB
GLSL

in vec2 f_coords;
layout(location = 0) out vec4 out_color;
#texture (depth_tex, 0, R)
uniform sampler2D depth_tex;
#include <common>
#include <gtao_common.glsl>
const float PI = 3.14159265;
const float HALF_PI = 1.57079633;
vec3 view_position(ivec2 texel)
{
vec2 size = vec2(textureSize(depth_tex, 0));
texel = clamp(texel, ivec2(0), ivec2(size) - 1);
float depth = max(texelFetch(depth_tex, texel, 0).r, 1e-6);
float ndcz = (param[1].x > 0.5 ? depth : depth * 2.0 - 1.0);
float z = -projection[3][2] / (ndcz + projection[2][2]);
vec2 ndc = (vec2(texel) + 0.5) / size * 2.0 - 1.0;
return vec3((-ndc.x * z - projection[2][0] * z) / projection[0][0],
(-ndc.y * z - projection[2][1] * z) / projection[1][1],
z);
}
void main()
{
vec2 size = vec2(textureSize(depth_tex, 0));
ivec2 center = ivec2(f_coords * size);
if (texelFetch(depth_tex, center, 0).r <= 0.0) {
out_color = vec4(1.0, 60000.0, 0.0, 0.0);
return;
}
vec3 P = view_position(center);
vec3 V = normalize(-P);
vec3 right = view_position(center + ivec2(1, 0)) - P;
vec3 left = P - view_position(center - ivec2(1, 0));
vec3 up = view_position(center + ivec2(0, 1)) - P;
vec3 down = P - view_position(center - ivec2(0, 1));
vec3 N = normalize(cross(abs(right.z) < abs(left.z) ? right : left, abs(up.z) < abs(down.z) ? up : down));
if (dot(N, V) < 0.0)
N = -N;
float radius = param[0].x;
float pixels = radius * projection[1][1] * 0.5 * size.y / -P.z;
if (pixels < 2.0) {
out_color = vec4(1.0, -P.z, octahedral_encode(mat3(inv_view) * N));
return;
}
pixels = min(pixels, size.y * 0.25);
int directions = max(int(param[0].z), 1);
int steps = max(int(param[0].w), 1);
float falloffrange = 0.6 * radius;
float falloffmul = -1.0 / falloffrange;
float falloffadd = (radius - falloffrange) / falloffrange + 1.0;
float noise = fract(52.9829189 * fract(dot(gl_FragCoord.xy, vec2(0.06711056, 0.00583715))));
float jitter = fract(noise * 1.61803399);
float visibility = 0.0;
vec3 bent = vec3(0.0);
for (int d = 0; d < directions; ++d)
{
float phi = (float(d) + noise) * PI / float(directions);
vec2 omega = vec2(cos(phi), sin(phi));
vec3 direction = vec3(omega, 0.0);
vec3 ortho = direction - dot(direction, V) * V;
vec3 axis = normalize(cross(ortho, V));
vec3 projected = N - axis * dot(N, axis);
float projectedlength = length(projected);
float cosn = clamp(dot(projected, V) / max(projectedlength, 1e-4), 0.0, 1.0);
float n = sign(dot(ortho, projected)) * acos(cosn);
float lowcos0 = cos(n + HALF_PI);
float lowcos1 = cos(n - HALF_PI);
float horizoncos0 = lowcos0;
float horizoncos1 = lowcos1;
for (int s = 0; s < steps; ++s)
{
float t = (float(s) + jitter) / float(steps);
t = t * t;
vec2 offset = omega * max(t * pixels, 1.5);
vec3 delta0 = view_position(center + ivec2(round(offset))) - P;
vec3 delta1 = view_position(center - ivec2(round(offset))) - P;
float length0 = length(delta0);
float length1 = length(delta1);
float weight0 = clamp(length(vec3(delta0.xy, delta0.z * (delta0.z > 0.0 ? 5.0 : 1.0))) * falloffmul + falloffadd, 0.0, 1.0);
float weight1 = clamp(length(vec3(delta1.xy, delta1.z * (delta1.z > 0.0 ? 5.0 : 1.0))) * falloffmul + falloffadd, 0.0, 1.0);
horizoncos0 = max(horizoncos0, mix(lowcos0, dot(delta0, V) / max(length0, 1e-4), weight0));
horizoncos1 = max(horizoncos1, mix(lowcos1, dot(delta1, V) / max(length1, 1e-4), weight1));
}
float h0 = -acos(clamp(horizoncos1, -1.0, 1.0));
float h1 = acos(clamp(horizoncos0, -1.0, 1.0));
h0 = n + clamp(h0 - n, -HALF_PI, HALF_PI);
h1 = n + clamp(h1 - n, -HALF_PI, HALF_PI);
float arc0 = (cosn + 2.0 * h0 * sin(n) - cos(2.0 * h0 - n)) * 0.25;
float arc1 = (cosn + 2.0 * h1 * sin(n) - cos(2.0 * h1 - n)) * 0.25;
visibility += projectedlength * (arc0 + arc1);
float middle = 0.5 * (h0 + h1);
bent += (V * cos(middle) + normalize(ortho) * sin(middle)) * projectedlength * (arc0 + arc1);
}
visibility = clamp(visibility / float(directions), 0.0, 1.0);
float fade = smoothstep(param[1].y * 0.75, param[1].y, -P.z);
bent = (dot(bent, bent) > 1e-8 ? normalize(bent) : N);
bent = normalize(mix(bent, N, fade));
out_color = vec4(mix(visibility, 1.0, fade), -P.z, octahedral_encode(mat3(inv_view) * bent));
}