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
|
#include "shaderCommon.h"
cbuffer constBuf : register(b0)
{
FluidShaderConst gParams;
};
float Sign(float x) { return x < 0.0 ? -1.0 : 1.0; }
bool solveQuadratic(float a, float b, float c, out float minT, out float maxT)
{
#if 0
minT = 0.0f;
maxT = 0.0f;
#endif
if (a == 0.0 && b == 0.0)
{
minT = maxT = 0.0;
return true;
}
float discriminant = b*b - 4.0*a*c;
if (discriminant < 0.0)
{
return false;
}
float t = -0.5*(b + Sign(b)*sqrt(discriminant));
minT = t / a;
maxT = c / t;
if (minT > maxT)
{
float tmp = minT;
minT = maxT;
maxT = tmp;
}
return true;
}
float sqr(float x) { return x * x; }
float ellipsoidDepthPS(FluidGeoOut input , out float depthOut : SV_DEPTH) : SV_TARGET
{
const float4x4 projectionMatrix = gParams.projection;
const float4x4 projectionMatrixInverse = gParams.inverseProjection;
const float3 invViewport = gParams.invViewport;
const float4 position = input.position;
// transform from view space to parameter space
//column_major
float4x4 invQuadric;
invQuadric._m00_m10_m20_m30 = input.invQ0;
invQuadric._m01_m11_m21_m31 = input.invQ1;
invQuadric._m02_m12_m22_m32 = input.invQ2;
invQuadric._m03_m13_m23_m33 = input.invQ3;
float4 ndcPos = float4(position.x*invViewport.x*2.0f-1.0f, (1.0f-position.y*invViewport.y)*2.0 - 1.0, 0.0f, 1.0);
float4 viewDir = mul(projectionMatrixInverse, ndcPos);
// ray to parameter space
float4 dir = mul(invQuadric, float4(viewDir.xyz, 0.0));
float4 origin = invQuadric._m03_m13_m23_m33;
// set up quadratric equation
float a = sqr(dir.x) + sqr(dir.y) + sqr(dir.z);
float b = dir.x*origin.x + dir.y*origin.y + dir.z*origin.z - dir.w*origin.w;
float c = sqr(origin.x) + sqr(origin.y) + sqr(origin.z) - sqr(origin.w);
float minT;
float maxT;
if (!solveQuadratic(a, 2.0 * b, c, minT, maxT))
{
discard;
}
{
float3 eyePos = viewDir.xyz*minT;
float4 ndcPos = mul(projectionMatrix, float4(eyePos, 1.0));
ndcPos.z /= ndcPos.w;
depthOut = ndcPos.z;
return eyePos.z;
}
}
|