111 lines
2.9 KiB
C++
111 lines
2.9 KiB
C++
#include <tuple>
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#include "math/vec.hpp"
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namespace bezier {
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template <typename T, int L, int M, int N, int O>
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struct vec_lmno {
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vec<L, T> l;
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vec<M, T> m;
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vec<N, T> n;
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vec<O, T> o;
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};
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struct triangle {
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int a;
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int b;
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int c;
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};
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template <typename T, int L, int M, int N, int O>
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constexpr inline
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vec_lmno<T, L, M, N, O>
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interpolate_quadratic(const T d,
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const vec<L, T>& l1, const vec<M, T>& m1, const vec<N, T>& n1, const vec<O, T>& o1,
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const vec<L, T>& l2, const vec<M, T>& m2, const vec<N, T>& n2, const vec<O, T>& o2,
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const vec<L, T>& l3, const vec<M, T>& m3, const vec<N, T>& n3, const vec<O, T>& o3)
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{
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T invd = 1.0 - d;
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T d1 = invd * invd;
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T d2 = 2.0 * d * invd;
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T d3 = d * d;
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vec<L, T> l;
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for (int i = 0; i < L; i++) {
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l[i] = l1[i] * d1 + l2[i] * d2 + l3[i] * d3;
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};
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vec<M, T> m;
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for (int i = 0; i < M; i++) {
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m[i] = m1[i] * d1 + m2[i] * d2 + m3[i] * d3;
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}
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vec<N, T> n;
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for (int i = 0; i < N; i++) {
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n[i] = n1[i] * d1 + n2[i] * d2 + n3[i] * d3;
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};
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vec<O, T> o;
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for (int i = 0; i < O; i++) {
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o[i] = o1[i] * d1 + o2[i] * d2 + o3[i] * d3;
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};
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return {l, m, n, o};
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}
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template <typename T, int L, int M, int N, int O>
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constexpr inline
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vec_lmno<T, L, M, N, O>
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interpolate_quadratic(const T d,
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const vec_lmno<T, L, M, N, O>& va,
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const vec_lmno<T, L, M, N, O>& vb,
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const vec_lmno<T, L, M, N, O>& vc)
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{
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return interpolate_quadratic<T>(d,
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va.l, va.m, va.n, va.o,
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vb.l, vb.m, vb.n, vb.o,
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vc.l, vc.m, vc.n, vc.o);
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}
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template <typename T, int L, int M, int N, int O>
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constexpr inline
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void
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tessellate(const int level,
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const vec_lmno<T, L, M, N, O> * control, // [9]
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vec_lmno<T, L, M, N, O> * vertices, // [2 * level * level]
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triangle * triangles,
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int vertex_base = 0)
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{
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vec_lmno<T, L, M, N, O> column[3][level + 1];
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T inv_level = 1.0 / level;
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for (int i = 0; i <= level; i++) {
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T d = inv_level * i;
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column[0][i] = interpolate_quadratic(d, control[0], control[3], control[6]);
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column[1][i] = interpolate_quadratic(d, control[1], control[4], control[7]);
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column[2][i] = interpolate_quadratic(d, control[2], control[5], control[8]);
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}
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for (int i = 0; i <= level; i++) {
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for (int j = 0; j <= level; j++) {
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T d = inv_level * j;
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*vertices++ = interpolate_quadratic(d, column[0][i], column[1][i], column[2][i]);
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}
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}
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for (int i = 0; i < level; i++) {
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for (int j = 0; j < level; j++) {
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int ix = vertex_base + j * (level + 1) + i;
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*triangles++ = {ix + 0,
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ix + (level + 1) + 0,
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ix + (level + 1) + 1};
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*triangles++ = {ix + 0,
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ix + (level + 1) + 1,
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ix + 1};
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}
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}
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}
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}
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