166 lines
4.2 KiB
C
166 lines
4.2 KiB
C
/*
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* Copyright 2011-2014 hasufell
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*
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* This file is part of a hasufell project.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation version 2 of the License only.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file bezier.c
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* This file provides operations and informational functions
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* on the bezier data type which is defined in bezier.h.
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* @brief operations on bezier curves
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*/
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#include "bezier.h"
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#include "vector.h"
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#include <stdint.h>
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#include <stdlib.h>
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/*
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* static function declaration
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*/
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static bool get_section_vec(const vector *a,
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const vector *b,
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vector *c,
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const float section);
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static vector *calculate_bezier_point_rec(const bez_curv *bez,
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const float section,
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const uint32_t deg);
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/**
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* Get the vector that is in between the to control
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* points a and b and in the specified section from 0 to 1.
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*
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* @param a first control point
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* @param b second control point
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* @param c store the result here [out]
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* @param section the section between 0 and 1
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* @return true/false for success/failure
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*/
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static bool get_section_vec(const vector *a,
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const vector *b,
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vector *c,
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const float section)
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{
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vector a_tmp,
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b_tmp;
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if (!a || !b || !c)
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return false;
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copy_vector(a, &a_tmp);
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copy_vector(b, &b_tmp);
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set_null_vector(c);
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SUB_VECTORS(&a_tmp, &b_tmp, c);
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VECTOR_LEN_SCAL_MUL(c, section, c);
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ADD_VECTORS(c, b, c);
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return true;
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}
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/**
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* Calculate a point on the bezier curve according to the
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* bezier vertices. If section is set to 0.5 then it will
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* return the vector to the point in the middle of the curve.
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*
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* @param bez the bezier curve to calcluate the point from
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* @param section the section which will be applied to all
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* lines between the bezier vertices
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* @param deg the degree of the bezier curve, this needs to be passed
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* because the function is recursive
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* @return the vector to the calculated point, newly allocated
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*/
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static vector *calculate_bezier_point_rec(const bez_curv *bez,
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const float section,
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const uint32_t deg)
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{
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bez_curv new_bez = { NULL, 0 };
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if (!get_reduced_bez_curv(bez, &new_bez, section))
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return NULL;
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if (bez->deg < deg)
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free(bez->vec);
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if (new_bez.deg > 0) {
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return calculate_bezier_point_rec(&new_bez, section, deg);
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} else {
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vector *result_vector = malloc(sizeof(*result_vector));
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*result_vector = new_bez.vec[0];
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free(new_bez.vec);
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return result_vector;
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}
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}
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/**
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* Calculate a point on the bezier curve according to the
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* bezier vertices. If section is set to 0.5 then it will
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* return the vector to the point in the middle of the curve.
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*
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* @param bez the bezier curve to calcluate the point from
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* @param section the section which will be applied to all
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* lines between the bezier vertices
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* @return the vector to the calculated point, newly allocated
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*/
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vector *calculate_bezier_point(const bez_curv *bez,
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const float section)
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{
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return calculate_bezier_point_rec(bez, section, bez->deg);
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}
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/**
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* Get the reduced bezier curve which is of one degree less
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* and strained between the defined sections of the old curve.
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*
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* @param bez the bezier curve the calcluate the next from
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* @param new_bez the new bezier curve, with a newly
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* allocated vector member [out]
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* @param section the section which will be applied to all
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* lines between the bezier vertices
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* @return true/false for success/failure
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*/
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bool get_reduced_bez_curv(const bez_curv *bez,
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bez_curv *new_bez,
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const float section)
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{
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vector *vec_arr;
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if (bez->deg < 1)
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return false;
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vec_arr = malloc(sizeof(*vec_arr) * bez->deg);
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for (uint32_t i = 0; i < bez->deg; i++) {
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vector new_vec;
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get_section_vec(&(bez->vec[i + 1]),
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&(bez->vec[i]),
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&new_vec,
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section);
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vec_arr[i] = new_vec;
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}
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new_bez->vec = vec_arr;
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new_bez->deg = bez->deg - 1;
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return true;
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}
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