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
|
[require]
GL >= 3.3
GLSL >= 3.30
GL_ARB_shader_storage_buffer_object
GL_INTEL_shader_atomic_float_minmax
[vertex shader passthrough]
[fragment shader]
#extension GL_ARB_shader_storage_buffer_object: require
#extension GL_INTEL_shader_atomic_float_minmax: require
layout(binding = 0, std430) buffer bufblock {
float value[8];
};
#define POS_NAN(x) (0x7f800000u | (0x007fffffu & uint(x)))
#define NEG_NAN(x) (0xff800000u | (0x007fffffu & uint(x)))
uniform uint comparitors[] = uint[](POS_NAN(0x00ffffff),
NEG_NAN(0x00ffffff),
POS_NAN(0x00555555),
NEG_NAN(0x00555555),
POS_NAN(0x00aaaaaa),
NEG_NAN(0x00aaaaaa),
floatBitsToUint(0.0),
floatBitsToUint(1.0));
out vec4 color;
void main()
{
uint idx = uint(gl_FragCoord.x + gl_FragCoord.y) % uint(value.length());
/* This compare-and-swap should never succeed because NaN is never
* equal to anything. Either the value in the SSBO or the value being
* compared is NaN. If the compare-and-swap succeeds, the SSBO
* element will forever be set to float(idx).
*/
atomicCompSwap(value[idx],
uintBitsToFloat(comparitors[idx]),
42.0);
color = value[idx] == 42.0
? vec4(1.0, 0.0, 0.0, 1.0)
: vec4(0.0, 1.0, 0.0, 1.0);
}
[test]
ssbo 0 32
ssbo 0 subdata int 0 0x7fffffff
ssbo 0 subdata int 4 0xffffffff
ssbo 0 subdata int 8 0x7fd55555
ssbo 0 subdata int 12 0xffd55555
ssbo 0 subdata float 16 0.0
ssbo 0 subdata float 20 1.0
ssbo 0 subdata int 24 0x7faaaaaa
ssbo 0 subdata int 28 0xffaaaaaa
clear color 0.5 0.5 0.5 0.5
clear
draw rect -1 -1 2 2
probe all rgba 0.0 1.0 0.0 1.0
|
