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
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
|
#define NO_OBJECT_ID uint(0)
#define EPSILON 0.00001
#define M_PI 3.14159265358979323846
#define CAVITY_BUFFER_RANGE 4.0
/* 4x4 bayer matrix prepared for 8bit UNORM precision error. */
#define P(x) (((x + 0.5) * (1.0 / 16.0) - 0.5) * (1.0 / 255.0))
const vec4 dither_mat4x4[4] = vec4[4](
vec4( P(0.0), P(8.0), P(2.0), P(10.0)),
vec4(P(12.0), P(4.0), P(14.0), P(6.0)),
vec4( P(3.0), P(11.0), P(1.0), P(9.0)),
vec4(P(15.0), P(7.0), P(13.0), P(5.0))
);
float bayer_dither_noise() {
ivec2 tx1 = ivec2(gl_FragCoord.xy) % 4;
ivec2 tx2 = ivec2(gl_FragCoord.xy) % 2;
return dither_mat4x4[tx1.x][tx1.y];
}
/* From http://aras-p.info/texts/CompactNormalStorage.html
* Using Method #4: Spheremap Transform */
vec3 normal_decode(vec2 enc)
{
vec2 fenc = enc.xy * 4.0 - 2.0;
float f = dot(fenc, fenc);
float g = sqrt(1.0 - f / 4.0);
vec3 n;
n.xy = fenc*g;
n.z = 1 - f / 2;
return n;
}
/* From http://aras-p.info/texts/CompactNormalStorage.html
* Using Method #4: Spheremap Transform */
vec2 normal_encode(vec3 n)
{
float p = sqrt(n.z * 8.0 + 8.0);
return vec2(n.xy / p + 0.5);
}
void fresnel(vec3 I, vec3 N, float ior, out float kr)
{
float cosi = clamp(dot(I, N), -1.0, 1.0);
float etai = 1.0;
float etat = ior;
if (cosi > 0) {
etat = 1.0;
etai = ior;
}
// Compute sini using Snell's law
float sint = etai / etat * sqrt(max(0.0, 1.0 - cosi * cosi));
// Total internal reflection
if (sint >= 1) {
kr = 1;
}
else {
float cost = sqrt(max(0.0, 1.0 - sint * sint));
cosi = abs(cosi);
float Rs = ((etat * cosi) - (etai * cost)) / ((etat * cosi) + (etai * cost));
float Rp = ((etai * cosi) - (etat * cost)) / ((etai * cosi) + (etat * cost));
kr = (Rs * Rs + Rp * Rp) / 2;
}
// As a consequence of the conservation of energy, transmittance is given by:
// kt = 1 - kr;
}
float calculate_transparent_weight(float z, float alpha)
{
#if 0
/* Eq 10 : Good for surfaces with varying opacity (like particles) */
float a = min(1.0, alpha * 10.0) + 0.01;
float b = -gl_FragCoord.z * 0.95 + 1.0;
float w = a * a * a * 3e2 * b * b * b;
#else
/* Eq 7 put more emphasis on surfaces closer to the view. */
// float w = 10.0 / (1e-5 + pow(abs(z) / 5.0, 2.0) + pow(abs(z) / 200.0, 6.0)); /* Eq 7 */
// float w = 10.0 / (1e-5 + pow(abs(z) / 10.0, 3.0) + pow(abs(z) / 200.0, 6.0)); /* Eq 8 */
// float w = 10.0 / (1e-5 + pow(abs(z) / 200.0, 4.0)); /* Eq 9 */
/* Same as eq 7, but optimized. */
float a = abs(z) / 5.0;
float b = abs(z) / 200.0;
b *= b;
float w = 10.0 / ((1e-5 + a * a) + b * (b * b)); /* Eq 7 */
#endif
return alpha * clamp(w, 1e-2, 3e2);
}
/* Special function only to be used with calculate_transparent_weight(). */
float linear_zdepth(float depth, vec4 viewvecs[3], mat4 proj_mat)
{
if (proj_mat[3][3] == 0.0) {
float d = 2.0 * depth - 1.0;
return -proj_mat[3][2] / (d + proj_mat[2][2]);
}
else {
/* Return depth from near plane. */
return depth * viewvecs[1].z;
}
}
vec3 view_vector_from_screen_uv(vec2 uv, vec4 viewvecs[3], mat4 proj_mat)
{
return (proj_mat[3][3] == 0.0)
? normalize(viewvecs[0].xyz + vec3(uv, 0.0) * viewvecs[1].xyz)
: vec3(0.0, 0.0, 1.0);
}
vec2 matcap_uv_compute(vec3 I, vec3 N, bool flipped)
{
/* Quick creation of an orthonormal basis */
float a = 1.0 / (1.0 + I.z);
float b = -I.x * I.y * a;
vec3 b1 = vec3(1.0 - I.x * I.x * a, b, -I.x);
vec3 b2 = vec3(b, 1.0 - I.y * I.y * a, -I.y);
vec2 matcap_uv = vec2(dot(b1, N), dot(b2, N));
if (flipped) {
matcap_uv.x = -matcap_uv.x;
}
return matcap_uv * 0.496 + 0.5;
}
|