blob: 3899365a7719c114fcc393cce840024c8c592b10 (
plain)
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
|
in vec2 pos;
in vec2 uvs;
uniform vec2 layerSelection;
uniform sampler2D colorBuffer;
uniform sampler2D cocBuffer;
flat out vec4 color;
out vec2 particlecoord;
#define M_PI 3.1415926535897932384626433832795
/* geometry shading pass, calculate a texture coordinate based on the indexed id */
void step_scatter()
{
ivec2 tex_size = textureSize(cocBuffer, 0);
vec2 texel_size = 1.0 / vec2(tex_size);
int t_id = gl_VertexID / 3; /* Triangle Id */
ivec2 texelco = ivec2(0);
/* some math to get the target pixel */
texelco.x = t_id % tex_size.x;
texelco.y = t_id / tex_size.x;
float coc = dot(layerSelection, texelFetch(cocBuffer, texelco, 0).rg);
/* Clamp to max size for performance */
coc = min(coc, 100.0);
if (coc >= 1.0) {
color = texelFetch(colorBuffer, texelco, 0);
/* find the area the pixel will cover and divide the color by it */
float alpha = 1.0 / (coc * coc * M_PI);
color *= alpha;
color.a = alpha;
}
else {
color = vec4(0.0);
}
/* Generate Triangle : less memory fetches from a VBO */
int v_id = gl_VertexID % 3; /* Vertex Id */
/* Extend to cover at least the unit circle */
const float extend = (cos(M_PI / 4.0) + 1.0) * 2.0;
/* Crappy diagram
* ex 1
* | \
* | \
* 1 | \
* | \
* | \
* 0 | x \
* | Circle \
* | Origin \
* -1 0 --------------- 2
* -1 0 1 ex
**/
gl_Position.x = float(v_id / 2) * extend - 1.0; /* int divisor round down */
gl_Position.y = float(v_id % 2) * extend - 1.0;
gl_Position.z = 0.0;
gl_Position.w = 1.0;
/* Generate Triangle */
particlecoord = gl_Position.xy;
gl_Position.xy *= coc * texel_size;
gl_Position.xy -= 1.0 - 0.5 * texel_size; /* NDC Bottom left */
gl_Position.xy += (0.5 + vec2(texelco) * 2.0) * texel_size;
}
out vec2 uvcoord;
void passthrough()
{
uvcoord = uvs;
gl_Position = vec4(pos, 0.0, 1.0);
}
void main()
{
#if defined(STEP_DOWNSAMPLE)
passthrough();
#elif defined(STEP_SCATTER)
step_scatter();
#elif defined(STEP_RESOLVE)
passthrough();
#endif
}
|