您最多选择25个主题
主题必须以中文或者字母或数字开头，可以包含连字符 (-)，并且长度不得超过35个字符
68 行
1.8 KiB
68 行
1.8 KiB
#ifndef __SPHERICALPOLYGON_HLSL__
|
|
#define __SPHERICALPOLYGON_HLSL__
|
|
|
|
#if !defined(SPHERICALPOLYGON_MAX_VERTS)
|
|
#error requires SPHERICALPOLYGON_MAX_VERTS
|
|
#endif
|
|
#if !defined(SPHERICALPOLYGON_NUM_VERTS)
|
|
#error requires SPHERICALPOLYGON_NUM_VERTS
|
|
#endif
|
|
|
|
void SphericalPolygon_CalcInteriorAngles(in float3 P[SPHERICALPOLYGON_MAX_VERTS], out float A[SPHERICALPOLYGON_MAX_VERTS])
|
|
{
|
|
const int LAST_VERT = (SPHERICALPOLYGON_NUM_VERTS - 1);
|
|
|
|
float3 N[SPHERICALPOLYGON_MAX_VERTS];
|
|
|
|
// calc plane normals
|
|
// where N[i] = normal of incident plane
|
|
// eg. N[i+0] = cross(C, A);
|
|
// N[i+1] = cross(A, B);
|
|
{
|
|
N[0] = -normalize(cross(P[LAST_VERT], P[0]));
|
|
for (int i = 1; i != SPHERICALPOLYGON_NUM_VERTS; i++)
|
|
{
|
|
N[i] = -normalize(cross(P[i - 1], P[i]));
|
|
}
|
|
}
|
|
|
|
// calc interior angles
|
|
{
|
|
for (int i = 0; i != LAST_VERT; i++)
|
|
{
|
|
A[i] = PI - sign(dot(N[i], P[i + 1])) * acos(clamp(dot(N[i], N[i + 1]), -1.0, 1.0));
|
|
}
|
|
A[LAST_VERT] = PI - sign(dot(N[LAST_VERT], P[0])) * acos(clamp(dot(N[LAST_VERT], N[0]), -1.0, 1.0));
|
|
}
|
|
|
|
/*
|
|
float3 nCA = cross(C, A);// plane normals
|
|
float3 nAB = cross(A, B);
|
|
float3 nBC = cross(B, C);
|
|
|
|
float wA = PI - sign(dot(nCA, B)) * acos(dot(nCA, nAB));
|
|
float wB = PI - sign(dot(nAB, C)) * acos(dot(nAB, nBC));
|
|
float wC = PI - sign(dot(nBC, A)) * acos(dot(nBC, nCA));
|
|
|
|
return float3(wA, wB, wC);
|
|
*/
|
|
}
|
|
|
|
void SphericalPolygon_CalcAreaFromInteriorAngles(in float A[SPHERICALPOLYGON_MAX_VERTS], out float area)
|
|
{
|
|
float E = 0.0;
|
|
for (int i = 0; i != SPHERICALPOLYGON_NUM_VERTS; i++)
|
|
{
|
|
E += A[i];
|
|
}
|
|
area = E - (SPHERICALPOLYGON_NUM_VERTS - 2.0) * PI;
|
|
}
|
|
|
|
void SphericalPolygon_CalcAreaFromProjectedPositions(in float3 P[SPHERICALPOLYGON_MAX_VERTS], out float area)
|
|
{
|
|
float A[SPHERICALPOLYGON_MAX_VERTS];
|
|
SphericalPolygon_CalcInteriorAngles(P, A);
|
|
SphericalPolygon_CalcAreaFromInteriorAngles(A, area);
|
|
}
|
|
|
|
#endif//__SPHERICALPOLYGON_HLSL__
|