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
|
////////////////////////////////////////////////////////////////////////////////
// Implicit Subdivision Shader for Terrain Rendering
//
#include "terrain_common.sh"
#include "fcull.sh"
BUFFER_RO(u_SubdBufferIn, uint, 8);
BUFFER_RW(u_CulledSubdBuffer, uint, 2);
BUFFER_RO(u_VertexBuffer, vec4, 6);
BUFFER_RO(u_IndexBuffer, uint, 7);
/**
* Compute LoD Shader
*
* This compute shader is responsible for updating the subdivision
* buffer and visible buffer that will be sent to the rasterizer.
*/
NUM_THREADS(COMPUTE_THREAD_COUNT, 1u, 1u)
void main()
{
// get threadID (each key is associated to a thread)
uint threadID = gl_GlobalInvocationID.x;
if (threadID >= u_AtomicCounterBuffer[2])
{
return;
}
// get coarse triangle associated to the key
uint primID = u_SubdBufferIn[threadID*2];
vec4 v_in[3];
v_in[0] = u_VertexBuffer[u_IndexBuffer[primID * 3 ]];
v_in[1] = u_VertexBuffer[u_IndexBuffer[primID * 3 + 1]];
v_in[2] = u_VertexBuffer[u_IndexBuffer[primID * 3 + 2]];
// compute distance-based LOD
uint key = u_SubdBufferIn[threadID*2+1];
vec4 v[3];
vec4 vp[3];
subd(key, v_in, v, vp);
uint targetLod; uint parentLod;
if (u_freeze == 0)
{
targetLod = uint(computeLod(v));
parentLod = uint(computeLod(vp));
}
else
{
targetLod = parentLod = findMSB(key);
}
updateSubdBuffer(primID, key, targetLod, parentLod);
// Cull invisible nodes
mat4 mvp = u_modelViewProj;
vec4 bmin = min(min(v[0], v[1]), v[2]);
vec4 bmax = max(max(v[0], v[1]), v[2]);
// account for displacement in bound computations
bmin.z = 0;
bmax.z = u_DmapFactor;
// update CulledSubdBuffer
if (u_cull == 0
|| frustumCullingTest(mvp, bmin.xyz, bmax.xyz) )
{
// write key
uint idx = 0;
atomicFetchAndAdd(u_AtomicCounterBuffer[1], 2, idx);
u_CulledSubdBuffer[idx] = primID;
u_CulledSubdBuffer[idx+1] = key;
}
}
|
