diff options
author | Campbell Barton <ideasman42@gmail.com> | 2020-11-07 12:14:40 +0300 |
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committer | Campbell Barton <ideasman42@gmail.com> | 2020-11-07 13:01:42 +0300 |
commit | 19a0df25e36d9e75d486e8c51ccb874095a93e91 (patch) | |
tree | 709474ad534da48c6c4636bee3e6930c885bc731 /source/blender/blenlib/intern/math_geom.c | |
parent | d2c102060d4489aa1fd68f6c33df4ba9c4add78b (diff) |
Cleanup: move plane array intersection into a function
Also add check to ensure a point isn't occluded by it's own plane,
which could happen if a small epsilon values are passed in.
Diffstat (limited to 'source/blender/blenlib/intern/math_geom.c')
-rw-r--r-- | source/blender/blenlib/intern/math_geom.c | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/source/blender/blenlib/intern/math_geom.c b/source/blender/blenlib/intern/math_geom.c index 1d2480f4d62..2b0018e7662 100644 --- a/source/blender/blenlib/intern/math_geom.c +++ b/source/blender/blenlib/intern/math_geom.c @@ -2298,6 +2298,81 @@ bool isect_plane_plane_v3(const float plane_a[4], } /** + * Intersect all planes, calling `callback_fn` for each point that intersects + * 3 of the planes that isn't outside any of the other planes. + * + * This can be thought of as calculating a convex-hull from an array of planes. + * + * \param eps_coplanar: Epsilon for testing if two planes are aligned (co-planar). + * \param eps_isect: Epsilon for testing of a point is behind any of the planes. + * + * \warning As complexity is a little under `O(N^3)`, this is only suitable for small arrays. + * + * \note This function could be optimized by some spatial structure. + */ +bool isect_planes_v3_fn( + const float planes[][4], + const int planes_len, + const float eps_coplanar, + const float eps_isect, + void (*callback_fn)(const float co[3], int i, int j, int k, void *user_data), + void *user_data) +{ + bool found = false; + + float n1n2[3], n2n3[3], n3n1[3]; + + for (int i = 0; i < planes_len; i++) { + const float *n1 = planes[i]; + for (int j = i + 1; j < planes_len; j++) { + const float *n2 = planes[j]; + cross_v3_v3v3(n1n2, n1, n2); + if (len_squared_v3(n1n2) <= eps_coplanar) { + continue; + } + for (int k = j + 1; k < planes_len; k++) { + const float *n3 = planes[k]; + cross_v3_v3v3(n2n3, n2, n3); + if (len_squared_v3(n2n3) <= eps_coplanar) { + continue; + } + + cross_v3_v3v3(n3n1, n3, n1); + if (len_squared_v3(n3n1) <= eps_coplanar) { + continue; + } + const float quotient = -dot_v3v3(n1, n2n3); + if (fabsf(quotient) < eps_coplanar) { + continue; + } + const float co_test[3] = { + ((n2n3[0] * n1[3]) + (n3n1[0] * n2[3]) + (n1n2[0] * n3[3])) / quotient, + ((n2n3[1] * n1[3]) + (n3n1[1] * n2[3]) + (n1n2[1] * n3[3])) / quotient, + ((n2n3[2] * n1[3]) + (n3n1[2] * n2[3]) + (n1n2[2] * n3[3])) / quotient, + }; + int i_test; + for (i_test = 0; i_test < planes_len; i_test++) { + const float *np_test = planes[i_test]; + if (((dot_v3v3(np_test, co_test) + np_test[3]) > eps_isect)) { + /* For low epsilon values the point could intersect it's own plane. */ + if (!ELEM(i_test, i, j, k)) { + break; + } + } + } + + if (i_test == planes_len) { /* ok */ + callback_fn(co_test, i, j, k, user_data); + found = true; + } + } + } + } + + return found; +} + +/** * Intersect two triangles. * * \param r_i1, r_i2: Retrieve the overlapping edge between the 2 triangles. |