1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
|
#pragma BLENDER_REQUIRE(common_math_geom_lib.glsl)
#pragma BLENDER_REQUIRE(bsdf_common_lib.glsl)
#pragma BLENDER_REQUIRE(bsdf_sampling_lib.glsl)
#pragma BLENDER_REQUIRE(raytrace_lib.glsl)
#pragma BLENDER_REQUIRE(surface_lib.glsl)
/* ------------ Refraction ------------ */
#define BTDF_BIAS 0.85
uniform sampler2D refractColorBuffer;
uniform float refractionDepth;
vec4 screen_space_refraction(vec3 vP, vec3 N, vec3 V, float ior, float roughnessSquared, vec4 rand)
{
float alpha = max(0.002, roughnessSquared);
/* Importance sampling bias */
rand.x = mix(rand.x, 0.0, BTDF_BIAS);
vec3 T, B;
make_orthonormal_basis(N, T, B);
float pdf;
/* Microfacet normal */
vec3 H = sample_ggx(rand.xzw, alpha, V, N, T, B, pdf);
/* If ray is bad (i.e. going below the plane) regenerate. */
if (F_eta(ior, dot(H, V)) < 1.0) {
H = sample_ggx(rand.xzw * vec3(1.0, -1.0, -1.0), alpha, V, N, T, B, pdf);
}
vec3 vV = viewCameraVec(vP);
float eta = 1.0 / ior;
if (dot(H, V) < 0.0) {
H = -H;
eta = ior;
}
vec3 R = refract(-V, H, 1.0 / ior);
R = transform_direction(ViewMatrix, R);
Ray ray;
ray.origin = vP;
ray.direction = R * 1e16;
RayTraceParameters params;
params.thickness = ssrThickness;
params.jitter = rand.y;
params.trace_quality = ssrQuality;
params.roughness = roughnessSquared;
vec3 hit_pos;
bool hit = raytrace(ray, params, false, true, hit_pos);
if (hit && (F_eta(ior, dot(H, V)) < 1.0)) {
hit_pos = get_view_space_from_depth(hit_pos.xy, hit_pos.z);
float hit_dist = distance(hit_pos, vP);
float cone_cos = cone_cosine(roughnessSquared);
float cone_tan = sqrt(1 - cone_cos * cone_cos) / cone_cos;
/* Empirical fit for refraction. */
/* TODO find a better fit or precompute inside the LUT. */
cone_tan *= 0.5 * fast_sqrt(f0_from_ior((ior < 1.0) ? 1.0 / ior : ior));
float cone_footprint = hit_dist * cone_tan;
/* find the offset in screen space by multiplying a point
* in camera space at the depth of the point by the projection matrix. */
float homcoord = ProjectionMatrix[2][3] * hit_pos.z + ProjectionMatrix[3][3];
/* UV space footprint */
cone_footprint = BTDF_BIAS * 0.5 * max(ProjectionMatrix[0][0], ProjectionMatrix[1][1]) *
cone_footprint / homcoord;
vec2 hit_uvs = project_point(ProjectionMatrix, hit_pos).xy * 0.5 + 0.5;
/* Texel footprint */
vec2 texture_size = vec2(textureSize(refractColorBuffer, 0).xy) / hizUvScale.xy;
float mip = clamp(log2(cone_footprint * max(texture_size.x, texture_size.y)), 0.0, 9.0);
vec3 spec = textureLod(refractColorBuffer, hit_uvs * hizUvScale.xy, mip).xyz;
float mask = screen_border_mask(hit_uvs);
return vec4(spec, mask);
}
return vec4(0.0);
}
|
