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Diffstat (limited to 'svg-flatten/src/flatten.cpp')
| -rw-r--r-- | svg-flatten/src/flatten.cpp | 231 |
1 files changed, 231 insertions, 0 deletions
diff --git a/svg-flatten/src/flatten.cpp b/svg-flatten/src/flatten.cpp new file mode 100644 index 0000000..e93f044 --- /dev/null +++ b/svg-flatten/src/flatten.cpp @@ -0,0 +1,231 @@ +/* Copied from Antigrain Graphics (AGG) v2.4 */ +/* Mirror: https://github.com/pelson/antigrain/blob/master/agg-2.4/src/agg_curves.cpp */ + +#include <flatten.hpp> +#include <cmath> + +using namespace gerbolyze; + +namespace gerbolyze { + const double curve_distance_epsilon = 1e-15; + const double curve_collinearity_epsilon = 1e-15; + const double curve_angle_tolerance_epsilon = 0.1; + constexpr unsigned curve_recursion_limit = 20; +} + +static inline double calc_sq_distance(double x1, double y1, double x2, double y2) +{ + double dx = x2-x1; + double dy = y2-y1; + return dx * dx + dy * dy; +} + +void curve4_div::run(double x1, double y1, double x2, double y2, double x3, double y3, double x4, double y4) { + m_points.clear(); + m_points.emplace_back(d2p{x1, y1}); + recursive_bezier(x1, y1, x2, y2, x3, y3, x4, y4, 0); + m_points.emplace_back(d2p{x4, y4}); +} + +void curve4_div::recursive_bezier(double x1, double y1, + double x2, double y2, + double x3, double y3, + double x4, double y4, + unsigned level) +{ + if(level > curve_recursion_limit) { + return; + } + + double pi = M_PI; + + // Calculate all the mid-points of the line segments + //---------------------- + double x12 = (x1 + x2) / 2; + double y12 = (y1 + y2) / 2; + double x23 = (x2 + x3) / 2; + double y23 = (y2 + y3) / 2; + double x34 = (x3 + x4) / 2; + double y34 = (y3 + y4) / 2; + double x123 = (x12 + x23) / 2; + double y123 = (y12 + y23) / 2; + double x234 = (x23 + x34) / 2; + double y234 = (y23 + y34) / 2; + double x1234 = (x123 + x234) / 2; + double y1234 = (y123 + y234) / 2; + + + // Try to approximate the full cubic curve by a single straight line + //------------------ + double dx = x4-x1; + double dy = y4-y1; + + double d2 = fabs(((x2 - x4) * dy - (y2 - y4) * dx)); + double d3 = fabs(((x3 - x4) * dy - (y3 - y4) * dx)); + double da1, da2, k; + + switch((int(d2 > curve_collinearity_epsilon) << 1) + + int(d3 > curve_collinearity_epsilon)) + { + case 0: + // All collinear OR p1==p4 + //---------------------- + k = dx*dx + dy*dy; + if(k == 0) { + d2 = calc_sq_distance(x1, y1, x2, y2); + d3 = calc_sq_distance(x4, y4, x3, y3); + + } else { + k = 1 / k; + da1 = x2 - x1; + da2 = y2 - y1; + d2 = k * (da1*dx + da2*dy); + da1 = x3 - x1; + da2 = y3 - y1; + d3 = k * (da1*dx + da2*dy); + + if(d2 > 0 && d2 < 1 && d3 > 0 && d3 < 1) { + // Simple collinear case, 1---2---3---4 + // We can leave just two endpoints + return; + } + + if(d2 <= 0) { + d2 = calc_sq_distance(x2, y2, x1, y1); + } else if(d2 >= 1) { + d2 = calc_sq_distance(x2, y2, x4, y4); + } else { + d2 = calc_sq_distance(x2, y2, x1 + d2*dx, y1 + d2*dy); + } + + if(d3 <= 0) { + d3 = calc_sq_distance(x3, y3, x1, y1); + } else if(d3 >= 1) { + d3 = calc_sq_distance(x3, y3, x4, y4); + } else { + d3 = calc_sq_distance(x3, y3, x1 + d3*dx, y1 + d3*dy); + } + + } + + if(d2 > d3) { + if(d2 < m_distance_tolerance_square) { + m_points.emplace_back(d2p{x2, y2}); + return; + } + } else { + if(d3 < m_distance_tolerance_square) { + m_points.emplace_back(d2p{x3, y3}); + return; + } + } + break; + + case 1: + // p1,p2,p4 are collinear, p3 is significant + //---------------------- + if(d3 * d3 <= m_distance_tolerance_square * (dx*dx + dy*dy)) { + if(m_angle_tolerance < curve_angle_tolerance_epsilon) { + m_points.emplace_back(d2p{x23, y23}); + return; + } + + // Angle Condition + //---------------------- + da1 = fabs(atan2(y4 - y3, x4 - x3) - atan2(y3 - y2, x3 - x2)); + if(da1 >= pi) da1 = 2*pi - da1; + + if(da1 < m_angle_tolerance) { + m_points.emplace_back(d2p{x2, y2}); + m_points.emplace_back(d2p{x3, y3}); + return; + } + + if(m_cusp_limit != 0.0) { + if(da1 > m_cusp_limit) + { + m_points.emplace_back(d2p{x3, y3}); + return; + } + } + } + break; + + case 2: + // p1,p3,p4 are collinear, p2 is significant + //---------------------- + if(d2 * d2 <= m_distance_tolerance_square * (dx*dx + dy*dy)) { + if(m_angle_tolerance < curve_angle_tolerance_epsilon) { + m_points.emplace_back(d2p{x23, y23}); + return; + } + + // Angle Condition + //---------------------- + da1 = fabs(atan2(y3 - y2, x3 - x2) - atan2(y2 - y1, x2 - x1)); + if(da1 >= pi) da1 = 2*pi - da1; + + if(da1 < m_angle_tolerance) { + m_points.emplace_back(d2p{x2, y2}); + m_points.emplace_back(d2p{x3, y3}); + return; + } + + if(m_cusp_limit != 0.0) { + if(da1 > m_cusp_limit) { + m_points.emplace_back(d2p{x2, y2}); + return; + } + } + } + break; + + case 3: + // Regular case + //----------------- + if((d2 + d3)*(d2 + d3) <= m_distance_tolerance_square * (dx*dx + dy*dy)) + { + // If the curvature doesn't exceed the distance_tolerance value + // we tend to finish subdivisions. + //---------------------- + if(m_angle_tolerance < curve_angle_tolerance_epsilon) { + m_points.emplace_back(d2p{x23, y23}); + return; + } + + // Angle & Cusp Condition + //---------------------- + k = atan2(y3 - y2, x3 - x2); + da1 = fabs(k - atan2(y2 - y1, x2 - x1)); + da2 = fabs(atan2(y4 - y3, x4 - x3) - k); + if(da1 >= pi) da1 = 2*pi - da1; + if(da2 >= pi) da2 = 2*pi - da2; + + if(da1 + da2 < m_angle_tolerance) { + // Finally we can stop the recursion + //---------------------- + m_points.emplace_back(d2p{x23, y23}); + return; + } + + if(m_cusp_limit != 0.0) { + if(da1 > m_cusp_limit) { + m_points.emplace_back(d2p{x2, y2}); + return; + } + + if(da2 > m_cusp_limit) { + m_points.emplace_back(d2p{x3, y3}); + return; + } + } + } + break; + } + + // Continue subdivision + //---------------------- + recursive_bezier(x1, y1, x12, y12, x123, y123, x1234, y1234, level + 1); + recursive_bezier(x1234, y1234, x234, y234, x34, y34, x4, y4, level + 1); +} + |